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# The right margin in this file is 65 characters.
=head1 NAME
Monit - utility for monitoring services on a Unix system
=head1 SYNOPSIS
B<monit> [options] {arguments}
=head1 DESCRIPTION
B<monit> is a utility for managing and monitoring processes,
programs, files, directories and filesystems on a Unix system.
Monit conducts automatic maintenance and repair and can execute
meaningful causal actions in error situations. E.g. Monit can
start a process if it does not run, restart a process if it does
not respond and stop a process if it uses too much resources. You
can use Monit to monitor files, directories and filesystems for
changes, such as timestamps changes, checksum changes or size
changes.
Monit is controlled via an easy to configure control file based
on a free-format, token-oriented syntax. Monit logs to syslog or
to its own log file and notifies you about error conditions via
customizable alert messages. Monit can perform various TCP/IP
network checks, protocol checks and can utilize SSL for such
checks. Monit provides a http(s) interface and you may use a
browser to access the Monit program.
=head1 GENERAL OPERATION
The behavior of Monit is controlled by command-line options
I<and> a run control file, L<monitrc|/"THE MONIT CONTROL FILE">,
the syntax of which we describe in a later section. Command-line
options override F<.monitrc> declarations.
The default location for F<monitrc> is F<~/.monitrc>. If this
file does not exist, Monit will try I</etc/monitrc> and a few
other places. See L<FILES|/"FILES"> for details. You can also
specify the control file directly by using the I<-c> command-line
switch to monit. For instance,
$ monit -c /var/monit/monitrc
Before Monit is started the first time, you can test the control
file for syntax errors:
$ monit -t
$ Control file syntax OK
If there was an error, Monit will print an error message to the
console, including the line number in the control file from where
the error was found.
Once you have a working Monit control file you can start Monit
from the console, like so:
$ monit
You can change some configuration directives via command-line
switches, but for simplicity it is recommended that you put these
in the control file.
If all goes well, Monit will now detach from the terminal and run
as a background process, i.e. as a daemon process. As a daemon,
Monit runs in cycles; It monitor services, then goes to sleep for
a configured period, then wakes up and start monitoring again in
an endless loop.
=head2 Options
The following options are recognized by Monit. However, it is
recommended that you set options (when applicable) directly in
the I<.monitrc> control file.
B<-c> I<file>
Use this control file
B<-d> I<n>
Run Monit as a daemon once per I<n> seconds. Or use I<"set
daemon"> in monitrc.
B<-g> I<name>
Set group name for start, stop, restart, monitor and
unmonitor action.
B<-l> I<logfile>
Print log information to this file. Or use I<"set logfile">
in monitrc.
B<-p> I<pidfile>
Use this lock file in daemon mode. Or use I<"set pidfile">
in monitrc.
B<-s> I<statefile>
Write state information to this file. Or use I<"set
statefile"> in monitrc.
B<-I>
Do not run in background (needed for run from init)
B<-t>
Run syntax check for the control file
B<-v>
Verbose mode, work noisy (diagnostic output)
B<-vv>
Very verbose mode, same as -v plus log stack-trace on error
B<-H> I<[filename]>
Print MD5 and SHA1 hashes of the file or of stdin if the
filename is omitted; Monit will exit afterwards
B<-V>
Print version number and patch level
B<-h>
Print a help text
=head2 Arguments
Once you have Monit running as a daemon process, you can call
Monit with one of the following arguments. Monit will then
connect to the Monit daemon (on TCP port 127.0.0.1:2812 by
default) and ask the Monit daemon to perform the requested
action. In other words; calling monit without arguments starts
the Monit daemon, and calling monit I<with> arguments enables you
to communicate with the Monit daemon process.
=over 4
=item start all
Start all services listed in the control file and enable
monitoring for them. If the group option is set (I<-g>), only
start and enable monitoring of services in the named group ("all"
is not required in this case).
=item start name
Start the named service and enable monitoring for it. The name is
a service entry name from the monitrc file.
=item stop all
Stop all services listed in the control file and disable their
monitoring. If the group option is set, only stop and disable
monitoring of the services in the named group (all" is not
required in this case).
=item stop name
Stop the named service and disable its monitoring. The name is a
service entry name from the monitrc file.
=item restart all
Stop and start I<all> services. If the group option is set, only
restart the services in the named group ("all" is not required in
this case).
=item restart name
Restart the named service. The name is a service entry name from
the monitrc file.
=item monitor all
Enable monitoring of all services listed in the control file. If
the group option is set, only start monitoring of services in the
named group ("all" is not required in this case).
=item monitor name
Enable monitoring of the named service. The name is a service
entry name from the monitrc file. Monit will also enable
monitoring of all services this service depends on.
=item unmonitor all
Disable monitoring of all services listed in the control file. If
the group option is set, only disable monitoring of services in
the named group ("all" is not required in this case).
=item unmonitor name
Disable monitoring of the named service. The name is a service
entry name from the monitrc file. Monit will also disable
monitoring of all services that depends on this service.
=item status
Print status information of each service.
=item summary
Print a short status summary.
=item reload
Reinitialize a running Monit daemon, the daemon will reread its
configuration, close and reopen log files.
=item quit
Kill the Monit daemon process
=item validate
Check all services listed in the control file. This action is
also the default behavior when Monit runs in daemon mode.
=item procmatch regex
Allows for easy testing of pattern for process match check. The
command takes regular expression as an argument and displays all
running processes matching the pattern.
=back
=head1 WHAT TO MONITOR?
You can use Monit to monitor daemon B<processes> or similar
programs running on localhost. Monit is particular useful for
monitoring daemon processes, such as those started at system boot
time from /etc/init.d/. For instance sendmail, sshd, apache and
mysql. In contrast to many other monitoring systems, Monit can act if
an error situation should occur, e.g.; if sendmail is not
running, monit can start sendmail again automatically or if
apache is using too many resources (e.g. if a DoS attack is in
progress) Monit can stop or restart apache and send you an alert
message. Monit can also monitor process characteristics, such as
how much memory or cpu cycles a process is using.
You can also use Monit to monitor B<files>, B<directories> and
B<filesystems> on localhost. Monit can monitor these items for
changes, such as timestamps changes, checksum changes or size
changes. This is also useful for security reasons - you can
monitor the md5 or sha1 checksum of files that should not change
and get an alert or perform an action if they should change.
Monit can monitor B<network connections> to various servers,
either on localhost or on remote hosts. TCP, UDP and Unix Domain
Sockets are supported. Network test can be performed on a
protocol level; Monit has built-in tests for the main Internet
protocols, such as HTTP, SMTP etc. Even if a protocol is not
supported you can still test the server because you can configure
Monit to send any data and test the response from the server.
Monit can be used to test B<programs> or scripts at certain
times, much like cron, but in addition, you can test the exit
value of a program and perform an action or send an alert if the
exit value indicate an error. This means that you can use Monit
to perform any type of check you can write a script for.
Finally, Monit can be used to monitor general B<system> resources
on localhost such as overall CPU usage, Memory and Load Average.
=head1 THE MONIT CONTROL FILE
Monit is configured and controlled via a control file called
I<monitrc>. The default location for this file is ~/.monitrc. If
this file does not exist, Monit will try /etc/monitrc, then
@sysconfdir@/monitrc and finally ./monitrc. The value of
@sysconfdir@ is given at configure time as ./configure
--sysconfdir. For instance, using I<./configure --sysconfdir
/var/monit/etc> will make Monit search for I<monitrc> in
I</var/monit/etc>
Monit uses its own Domain Specific Language (DSL); The control
file consists of a series of service entries and global option
statements in a free-format, token-oriented syntax.
Comments begin with a B<#> and extend through the end of the
line. There are three kinds of tokens in the control file:
I<keywords>, I<numbers> and I<strings>. On a semantic level, the
control file consists of only three type of entries:
=over 4
=item 1. Global set-statements
A global set-statement starts with the keyword I<set> and the
item to configure.
=item 2. Global include-statement
The include statement consists of the keyword I<include> and
a glob string.
=item 3. One or more service entry statements.
A service entry starts with the keyword I<check> followed by the
service type.
=back
The meaning of the various statements will be explained in the
following sections.
=head1 LOGGING
Monit will log status and error messages to a log file. Use the
I<set logfile> statement in the monitrc control file. To setup
Monit to log to its own logfile, use e.g. I<set logfile
/var/log/monit.log>. If B<syslog> is given as a value for the
I<-l> command-line switch (or the keyword I<set logfile syslog>
is found in the control file) Monit will use the B<syslog> system
daemon to log messages with a priority assigned to each message
based on the context. To turn off logging, simply do not set the
logfile in the control file (and of course, do not use the -l
switch)
=head1 DAEMON MODE
Use
set daemon n (where n is a number in seconds)
to specify Monit's poll cycle length and run Monit in daemon
mode. You must specify a numeric argument which is a polling
interval in seconds. In daemon mode, Monit detaches from the
console, puts itself in the background and runs continuously,
monitoring each specified service and then goes to sleep for the
given poll interval, wakes up and start monitoring again in an
endless cycle.
Alternatively, you can use the I<-d> command line switch to set
the poll interval, but it is strongly recommended to set the poll
interval in your I<~/.monitrc> file, by using I<set daemon>.
Monit will then always start in daemon mode. If you do not use
this statement and do not start monit with the -d option, Monit
will just run through the service checks once and then exit. This
may be useful in some situations, but Monit is primarily designed
to run as a daemon process.
Calling monit with a Monit daemon running in the background sends
a wake-up signal to the daemon, forcing it to check services
immediately. Calling monit with the quit argument will kill a
running Monit daemon process instead of waking it up.
=head1 INIT SUPPORT
The I<set init> statement prevents Monit from transforming itself
into a daemon process. Instead Monit will run as a foreground
process. (You should still use set daemon to specify the poll
cycle).
This is required to run Monit from init. Using init to start
Monit is probably the best way to run Monit if you want to be
certain that you always have a running Monit daemon on your
system. Another option is to run Monit from crontab. In any case,
you should make sure that the control file does not have any
syntax errors before you start Monit from init or crontab.
To setup Monit to run from init, you can either use the set init
statement in Monit's control file or use the -I option from the
command line. Here is what you must add to /etc/inittab:
# Run Monit in standard run-levels
mo:2345:respawn:/usr/local/bin/monit -Ic /etc/monitrc
After you have modified init's configuration file, you can run
the following command to re-examine /etc/inittab and start Monit:
telinit q
For systems without telinit:
kill -1 1
If Monit is used to monitor services that are also started at
boot time (e.g. services started via SYSV init rc scripts or via
inittab) then, in some cases, a race condition could occur. That
is; if a service is slow to start, Monit can assume that the
service is not running and possibly try to start it and raise an
alert, while, in fact the service is already about to start or
already in its startup sequence. Please see the FAQ for a
solution to this problem.
=head1 INCLUDE FILES
The Monit control file, I<monitrc>, can include additional
configuration files. This feature helps one to maintain a certain
structure or to place repeating settings into one file. Include
statements can be placed at virtually any spot. The syntax is the
following:
include globstring
The globstring is any kind of string as defined in glob(7). Thus,
you can refer to a single file or you can load several files at
once. If you want to use whitespace in your string the globstring
need to be embedded into quotes (') or double quotes ("). If the
globstring matches a directory instead of a file, it is silently
ignored.
Any I<include> statements in included files are parsed as in the
main control file.
If the globstring matches several results, the files are included
in a non sorted manner. If you need to rely on a certain order,
you might need to use single I<include> statements.
An example,
include /etc/monit.d/*.cfg
This will load any file matching the globstring. That is, all
files in I</etc/monit.d> that ends with the prefix I<.cfg>.
=head1 GROUP SUPPORT
Service entries in the control file, I<monitrc>, can be grouped
together by the I<group> statement. The syntax is simply (keyword
in capital):
GROUP groupname
With this statement it is possible to group similar service
entries together and manage them as a whole. Monit provides
functions to start, stop, restart, monitor and unmonitor a
group of services, like so:
To start a group of services from the console:
Monit -g <groupname> start
To stop a group of services:
Monit -g <groupname> stop
To restart a group of services:
Monit -g <groupname> restart
Note:
the I<status> and I<summary> commands don't support the -g
option and will print the state of all services.
Service can be added to multiple groups by adding group statement
multiple times:
group www
group filesystem
=head1 MONITORING MODE
Monit supports three monitoring modes per service: I<active>,
I<passive> and I<manual>. See also the example section below for
usage of the mode statement.
In I<active> mode, Monit will monitor a service and in case of
problems Monit will act and raise alerts, start, stop or restart
the service. Active mode is the default mode.
In I<passive> mode, Monit will passively monitor a service and
specifically B<not> try to fix a problem, but it will still raise
alerts in case of a problem.
For use in clustered environments there is also a I<manual>
mode. In this mode, Monit will enter I<active> mode B<only> if a
service was brought under monit's control, for example by
executing the following command in the console:
Monit start sybase
(Monit will call sybase's start method and enable monitoring)
If a service was not started by Monit or was stopped or disabled
for example by:
Monit stop sybase
(Monit will call sybase's stop method and disable monitoring)
Monit will then not monitor the service. This allows for having
services configured in monitrc and start it with Monit only if it
should run. This feature can be used to build a simple failsafe
cluster.
A service's monitoring state is persistent across Monit restart.
This means that you probably would like to make certain that
services in manual mode are stopped or in unmonitored mode at
server shutdown. Do for instance the following in a server
shutdown script:
Monit stop sybase
or
Monit unmonitor sybase
If you use Monit in a HA-cluster you should place the state file
in a temporary filesystem so if the machine should crash and the
stand-by machine take over services, any manual monitoring mode
services that were started on the crashed machine won't be
started on reboot. Use for example:
set statefile /tmp/monit.state
=head1 ALERT MESSAGES
Monit will raise an email alert in the following situations:
o A service timed out
o A service does not exist
o A service related data access problem
o A service related program execution problem
o A service is of invalid object type
o A program status failed
o A icmp problem
o A port connection problem
o A resource statement match
o A file checksum problem
o A file size problem
o A file/directory timestamp problem
o A file/directory/filesystem permission problem
o A file/directory/filesystem uid problem
o A file/directory/filesystem gid problem
o An action is done per administrator's request
Monit will send an alert each time a monitored object changed.
This involves:
o Monit started, stopped or reloaded
o A file checksum changed
o A file size changed
o A file content match
o A file/directory timestamp changed
o A filesystem mount flags changed
o A process PID changed
o A process PPID changed
You use the alert statement to notify Monit that you want alert
messages sent to an email address. If you do not specify an alert
statement, Monit will not send alert messages.
There are two forms of alert statement:
o Global - common for all services
o Local - per service
In both cases you can use more than one alert statement. In other
words, you can send many different emails to many different
addresses.
Recipients in the global and in the local lists are alerted when
a service failed, recovered or changed. If the same email address
is in the global and in the local list, Monit will only send one
alert. Local (per service) defined alert email addresses override
global addresses in case of a conflict. Finally, you may choose
to only use a global alert list (recommended), a local per
service list or both.
It is also possible to disable the global alerts locally for
particular service(s) and recipients.
=head2 Setting a global alert statement
If a change occurred on a monitored services, Monit will send an
alert to all recipients in the global list who has registered
interest for the event type. Here is the syntax for the global
alert statement:
=over 4
=item SET ALERT mail-address [ [NOT] {events}] [MAIL-FORMAT
{mail-format}] [REMINDER number]
=back
Simply using the following in the global section of monitrc:
set alert foo@bar
will send a default email to the address foo@bar whenever an
event occurred on any service. Such an event may be that a
service timed out, a service doesn't exist and so on. If you want
to send alert messages to more email addresses, add a I<set alert
'email'> statement for each address.
For explanations of the I<events, MAIL-FORMAT and REMINDER>
keywords above, please see below.
You can also use the NOT option ahead of the events list which
will reverse the meaning of the list. That is, only send alerts
for events I<not> in the list. This can save you some
configuration bytes if you are interested in most events except a
few.
=head2 Setting a local alert statement
Each service can also have its own recipient list.
=over 4
=item ALERT mail-address [ [NOT] {events}] [MAIL-FORMAT
{mail-format}] [REMINDER number]
=back
or
=over 4
=item NOALERT mail-address
=back
If you only want an alert message sent for certain events and for
certain service(s), for example only for timeout events or only
if a service died, then postfix the alert-statement with a filter
block:
check process myproc with pidfile /var/run/my.pid
alert foo@bar only on { timeout, nonexist }
...
(I<only> and I<on> are noise keywords, ignored by Monit. As a
side note; Noise keywords are used in the control file grammar to
make an entry resemble English and thus make it easier to read
(or, so goes the philosophy). The full set of available noise
keywords are listed below in the Control File section).
You can also setup to send alerts for all events except some by
putting the word I<not> ahead of the list. For example, if you
want to receive alerts for all events except Monit instance
events, you can write (note that the noise words 'but' and 'on'
are optional):
check system myserver
alert foo@bar but not on { instance }
...
instead of:
alert foo@bar on { action
checksum
connection
content
data
exec
fsflags
gid
icmp
invalid
nonexist
permission
pid
ppid
resource
size
status
timeout
timestamp
uid
uptime }
This will send alerts for all events to foo@bar, except Monit
instance events. An instance event BTW, is an event fired
whenever the Monit program start or stop.
Event filtering can be used to send an email to different email
addresses depending on the events that occurred. For instance:
alert foo@bar { nonexist, timeout, resource, icmp, connection }
alert security@bar on { checksum, permission, uid, gid }
alert manager@bar
This will send an alert message to foo@bar whenever a nonexist,
timeout, resource or connection problem occurs and a message to
security@bar if a checksum, permission, uid or gid problem
occurs. And finally, a message to manager@bar whenever any error
event occurs.
Here is the list of events you can use in a mail-filter: I<action,
checksum, connection, content, data, exec, fsflags, gid, icmp,
instance, invalid, nonexist, permission, pid, ppid, resource, size,
status, timeout, timestamp, uid, uptime>
You can also disable the alerts locally using the NOALERT
statement. This is useful if you have lots of services monitored
and are using the global alert statement, but don't want to
receive alerts for some minor subset of services:
noalert appadmin@bar
For example, if you stick the noalert statement in a 'check
system' entry, you won't receive system related alerts (such as
Monit instance started/stopped/reloaded alert, system overloaded
alert, etc.) but will receive alerts for all other monitored
services.
The following example will alert foo@bar on all events on all
services by default, except the service mybar which will send an
alert only on timeout. The trick is based on the fact that local
definition of the same recipient overrides the global setting
(including registered events and mail format):
set alert foo@bar
check process myfoo with pidfile /var/run/myfoo.pid
...
check process mybar with pidfile /var/run/mybar.pid
alert foo@bar only on { timeout }
=head2 Alert message layout
Monit provides a default mail message layout that is short and to
the point. Here's an example of a standard alert mail sent by
monit:
From: monit@tildeslash.com
Subject: Monit alert -- Does not exist apache
To: hauk@tildeslash.com
Date: Thu, 04 Sep 2003 02:33:03 +0200
Does not exist Service apache
Date: Thu, 04 Sep 2003 02:33:03 +0200
Action: restart
Host: www.tildeslash.com
Your faithful employee,
monit
If you want to, you can change the format of this message with
the optional I<mail-format> statement. The syntax for this
statement is as follows:
mail-format {
from: monit@localhost
reply-to: support@domain.com
subject: $SERVICE $EVENT at $DATE
message: Monit $ACTION $SERVICE at $DATE on $HOST: $DESCRIPTION.
Yours sincerely,
monit
}
Where the keyword I<from:> is the email address Monit should
pretend it is sending from. It does not have to be a real mail
address, but it must be a proper formatted mail address, on the
form: name@domain. The I<reply-to:> keyword can be used to set
the reply-to mail header. The keyword I<subject:> is for the
email subject line. The subject must be on only I<one> line. The
I<message:> keyword denotes the mail body. If used, this keyword
should always be the last in a mail-format statement. The mail
body can be as long as you want, but must B<not> contain the '}'
character.
All of these format keywords are optional, but if used, you must
provide at least one. Thus if you only want to change the from
address Monit is using you can do:
set alert foo@bar with mail-format { from: bofh@bar.baz }
From the previous example you will notice that some special $XXX
variables were used. If used, they will be substituted and
expanded into the text with these values:
=over 4
=item * I<$EVENT>
A string describing the event that occurred. The values are
fixed and are:
Event: | Failure state: | Success state:
-------------------------------------------------------------------
ACTION | "Action done" | "Action done"
CHECKSUM | "Checksum failed" | "Checksum succeeded"
CONNECTION| "Connection failed" | "Connection succeeded"
CONTENT | "Content failed", | "Content succeeded"
DATA | "Data access error" | "Data access succeeded"
EXEC | "Execution failed" | "Execution succeeded"
FSFLAG | "Filesystem flags failed"| "Filesystem flags succeeded"
GID | "GID failed" | "GID succeeded"
ICMP | "ICMP failed" | "ICMP succeeded"
INSTANCE | "Monit instance changed" | "Monit instance changed not"
INVALID | "Invalid type" | "Type succeeded"
NONEXIST | "Does not exist" | "Exists"
PERMISSION| "Permission failed" | "Permission succeeded"
PID | "PID failed" | "PID succeeded"
PPID | "PPID failed" | "PPID succeeded"
RESOURCE | "Resource limit matched" | "Resource limit succeeded"
SIZE | "Size failed" | "Size succeeded"
STATUS | "Status failed" | "Status succeeded"
TIMEOUT | "Timeout" | "Timeout recovery"
TIMESTAMP | "Timestamp failed" | "Timestamp succeeded"
UID | "UID failed" | "UID succeeded"
UPTIME | "Uptime failed" | "Uptime succeeded"
=item * I<$SERVICE>
The service entry name in monitrc
=item * I<$DATE>
The current time and date (RFC 822 date style).
=item * I<$HOST>
The name of the host Monit is running on
=item * I<$ACTION>
The name of the action which was done. Action names are fixed
and are:
Action: | Name:
--------------------
ALERT | "alert"
EXEC | "exec"
RESTART | "restart"
START | "start"
STOP | "stop"
UNMONITOR| "unmonitor"
=item * I<$DESCRIPTION>
The description of the error condition
=back
=head2 Setting a global mail format
It is possible to set a standard mail format with the following
global set-statement (keywords are in capital):
=over 4
=item SET MAIL-FORMAT {mail-format}
=back
Format set with this statement will apply to every alert
statement that does I<not> have its own specified mail-format.
This statement is most useful for setting a default from address
for messages sent by monit, like so:
set mail-format { from: monit@foo.bar.no }
=head2 Setting an error reminder
Monit by default sends just one error notification if a service
failed and another when it recovered. If you want to be notified
more then once if a service remains in a failed state, you can
use the reminder option to the alert statement (keywords are in
capital):
=over 4
=item ALERT ... [WITH] REMINDER [ON] number [CYCLES]
=back
For example if you want to be notified each tenth cycle if a
service remains in a failed state, you can use:
alert foo@bar with reminder on 10 cycles
Likewise if you want to be notified on each failed cycle, you can
use:
alert foo@bar with reminder on 1 cycle
=head2 Setting a mail server for alert messages
The mail server Monit should use to send alert messages is
defined with a global set statement (keywords are in capital and
optional statements in [brackets]):
SET MAILSERVER {hostname|ip-address [PORT port]
[USERNAME username] [PASSWORD password]
[using SSLV2|SSLV3|TLSV1] [CERTMD5 checksum]}+
[with TIMEOUT X SECONDS]
[using HOSTNAME hostname]
The port statement allows one to use SMTP servers other then those
listening on port 25. If omitted, port 25 is used unless ssl or
tls is used, in which case port 465 is used by default.
Monit support plain smtp authentication - you can set a username
and a password using the USERNAME and PASSWORD options.
To use secure communication, use the SSLV2, SSLV3 or TLSV1
options, you can also specify the server certificate checksum
using CERTMD5 option.
As you can see, it is possible to set several SMTP servers. If
Monit cannot connect to the first server in the list it will try
the second server and so on. Monit has a default 5 seconds
connection timeout and if the SMTP server is slow, Monit could
timeout when connecting or reading from the server. If this is
the case, you can use the optional timeout statement to explicit
set the timeout to a higher value if needed. Here is an example
for setting several mail servers:
set mailserver mail.tildeslash.com, mail.foo.bar port 10025
username "Rabbi" password "Loew" using tlsv1, localhost
with timeout 15 seconds
Here Monit will first try to connect to the server
"mail.tildeslash.com", if this server is down Monit will try
"mail.foo.bar" on port 10025 using the given credentials via tls
and finally "localhost". We also set an explicit connect and read
timeout; If Monit cannot connect to the first SMTP server in the
list within 15 seconds it will try the next server and so on. The
I<set mailserver ..> statement is optional and if not defined
Monit will not send email alerts. Not setting a mail server is
recommended only if alert notification is delegated to M/Monit.
Monit, by default, use the local host name in SMTP HELO/EHLO and
in the Message-ID header. Some mail servers check this
information against DNS for spam protection and can reject the
email if the DNS and the hostname used in the transaction does
not match. If this is the case, you can override the default
local host name by using the HOSTNAME option:
set mailserver mail.tildeslash.com using hostname
"myhost.example.org"
=head2 Event queue
If the MTA (mail server) for sending alerts is not available,
Monit I<can> queue events on the local file-system until the MTA
recover. Monit will then post queued events in order with their
original timestamp so the events are not lost. This feature is
most useful if Monit is used together with M/Monit and when event
history is important.
The event queue is persistent across Monit restarts and provided
that the back-end filesystem is persistent too, across system
restart as well.
By default, the queue is disabled and if the alert handler fails,
Monit will simply drop the alert message. To enable the event
queue, add the following statement to the Monit control file:
SET EVENTQUEUE BASEDIR <path> [SLOTS <number>]
The <path> is the path to the directory where events will be
stored. Optionally if you want to limit the queue size, use the
slots option to only store up to I<number> event messages. If the
slots option is not used, Monit will store as many events as the
backend filesystem allows.
Example:
set eventqueue
basedir /var/monit
slots 5000
Events are stored in a binary format, with one file per event.
The file size is ca. 130 bytes or a bit more (depending on the
message length). The file name is composed of the unix timestamp,
underscore and the service name, for example:
/var/monit/1131269471_apache
If you are running more then one Monit instance on the same
machine, you B<must> use separated event queue directories to
avoid sending wrong alerts to the wrong addresses.
If you want to purge the queue by hand, that is, remove queued
event-files, Monit should be stopped before the removal.
=head1 SERVICE TIMEOUT
B<Monit> provides a service timeout mechanism for situations
where a service simply refuses to start or respond over a longer
period.
The timeout mechanism is based on number of service restarts and
number of poll-cycles. For example, if a service had I<x>
restarts within I<y> poll-cycles (where I<x> <= I<y>) then Monit
will perform an action (for example unmonitor the service). If a
timeout occurs, Monit will send an alert message if you have
register interest for this event.
The syntax for the timeout statement is as follows (keywords are
in capital):
=over 4
=item IF <number> RESTART <number> CYCLE(S) THEN <action>
=back
Here is an example where Monit will unmonitor the service if it
was restarted 2 times within 3 cycles:
if 2 restarts within 3 cycles then unmonitor
To have Monit check the service again after a monitoring was
disabled, run 'monit monitor <servicename>' from the command
line.
Example for setting custom exec on timeout:
if 5 restarts within 5 cycles then exec "/foo/bar"
Example for stopping the service:
if 7 restarts within 10 cycles then stop
=head1 SERVICE TESTS
Monit provides several tests you can use in a 'check service'
entry to test a service. There are two classes of tests:
variable and constant tests. That is, the condition we test
is either constant e.g. a number or it can vary.
A constant test has this general format:
=over 4
=item IF <TEST> [[<X>] [TIMES WITHIN] <Y> CYCLES] THEN ACTION
[ELSE IF SUCCEEDED [[<X>] [TIMES WITHIN] <Y> CYCLES]
THEN ACTION]
=back
If the <TEST> condition should evaluate to true, then the
selected action is executed each cycle the test condition remains
true. The comparison value is constant. Recovery action is
evaluated only once (on a failed to succeeded state change only).
The 'ELSE IF SUCCEEDED' part is optional, if omitted, Monit will
still send an alert on recovery. The alert is sent only once for
each state change unless overridden by the 'reminder' alert
option.
A variable test has this general format:
=over 4
=item IF CHANGED <TEST> [[<X>] [TIMES WITHIN] <Y> CYCLES]
THEN ACTION
=back
If the <TEST> should evaluate to true, then the selected action
is executed once. The comparison value is a variable where the
last result becomes the new value and is used for comparisons in
future cycles. An alert is delivered each time the condition
becomes true.
You can use this test for alerts or for some automatic action,
for example to reload monitored process after its configuration
file was changed. Variable tests are supported for 'checksum',
'size', 'pid, 'ppid' and 'timestamp' tests only.
=over 4
=item ... [[<X>] [TIMES WITHIN] <Y> CYCLES] ...
=back
If a test match, its action is executed at once. This behavior
can optionally be changed and you can for instance require that a
test must match over several poll cycles before the action is
executed by using the statement above. You can use this in
several ways. For example:
if failed port 80 for 3 times within 5 cycles then alert
or
if failed port 80 for 10 cycles then unmonitor
If you don't specify <X> times, it equals <Y> by default, thus
the test match if it evaluate to true for <Y> consecutive cycles.
It is possible to use this option to tune and prevent a rush of
notifications. You can use this option for failed, succeeded,
recovered or changed rules. Here is a more complex example:
check filesystem rootfs with path /dev/hda1
if space usage > 80% for 5 times within 15 cycles
then alert else if succeeded for 10 cycles then alert
if space usage > 90% for 5 cycles then
exec '/try/to/free/the/space'
In each test you must select the action to be executed from this
list:
=over 4
=item *
B<ALERT> sends the user an alert event on each state change (for
constant tests) or on each change (for variable tests).
=item *
B<RESTART> restarts the service I<and> sends an alert. Restart is
conducted by first calling the service's registered stop method
and then the service's start method.
=item *
B<START> starts the service by calling the service's registered
start method I<and> send an alert.
=item *
B<STOP> stops the service by calling the service's registered
stop method I<and> send an alert. If Monit stops a service it
will not be checked by Monit anymore nor restarted again later.
To reactivate monitoring of the service again you must explicitly
enable monitoring from the web interface or from the console,
e.g. 'monit monitor apache'.
=item *
B<EXEC> can be used to execute an arbitrary program I<and> send
an alert. If you choose this action you must state the program to
be executed and if the program require arguments you must enclose
the program and its arguments in a quoted string. You may
optionally specify the uid and gid the executed program should
switch to upon start. For instance:
exec "/usr/local/tomcat/bin/startup.sh"
as uid nobody and gid nobody
The uid and gid switch can be useful if the program to be started
cannot change to a lesser privileged user and group. This is
typically needed for Java Servers. Remember, if Monit is run by
the superuser, then all programs executed by Monit will be
started with superuser privileges unless the uid and gid
extension was used.
=item *
B<UNMONITOR> will disable monitoring of the service I<and> send
an alert. The service will not be checked by Monit anymore nor
restarted again later. To reactivate monitoring of the service
you must explicitly enable monitoring from monit's web interface
or from the console using the monitor argument.
=back
=head2 EXISTENCE TESTING
Monit's default action when services does not exist (for example
a process is not running, a file doesn't exist, etc.) is to
perform service restart action.
The default action can be overrided with following statement:
=over 4
=item IF [DOES] NOT EXIST [[<X>] <Y> CYCLES] THEN action
[ELSE IF SUCCEEDED [[<X>] <Y> CYCLES] THEN action]
=back
I<action> is a choice of "ALERT", "RESTART", "START", "STOP",
"EXEC" or "UNMONITOR".
Example:
check file with path /cifs/mydata
if does not exist for 5 cycles then exec "/usr/bin/mount_cifs.sh"
=head2 RESOURCE TESTING
Monit can examine how much system resources a service is using.
This test can only be used within a system or process service
entry in the Monit control file.
Depending on system or process characteristics, services can be
stopped or restarted and alerts can be generated. Thus it is
possible to utilize systems which are idle and to spare system
under high load.
The full syntax for a resource-statement used for resource
testing is as follows (keywords are in capital and optional
statements in [brackets]),
=over 4
=item IF resource operator value [[<X>] <Y> CYCLES] THEN action
[ELSE IF SUCCEEDED [[<X>] <Y> CYCLES] THEN action]
=back
I<resource> is a choice of "CPU", "TOTALCPU",
"CPU([user|system|wait])", "MEMORY", "SWAP", "CHILDREN", "TOTALMEMORY",
"LOADAVG([1min|5min|15min])". Some resource tests can be used
inside a check system entry, some in a check process entry and
some in both:
System only resource tests:
CPU([user|system|wait]) is the percent of time the system spend
in user or system/kernel space. Some systems such as linux 2.6
supports a 'wait' indicator as well.
SWAP is the swap usage of the system in either percent (of the
systems total) or as an amount (Byte, kB, MB, GB).
Process only resource tests:
CPU is the CPU usage of the process itself (percent).
TOTALCPU is the total CPU usage of the process and its children
in (percent). You will want to use TOTALCPU typically for
services like Apache web server where one master process forks the
child processes as workers.
CHILDREN is the number of child processes of the process.
TOTALMEMORY is the memory usage of the process and its child
processes in either percent or as an amount (Byte, kB, MB, GB).
System and process resource tests:
MEMORY is the memory usage of the system or of a process (without
children) in either percent (of the systems total) or as an
amount (Byte, kB, MB, GB).
LOADAVG([1min|5min|15min]) refers to the system's load average.
The load average is the number of processes in the system run
queue, averaged over the specified time period.
I<operator> is a choice of "<", ">", "!=", "==" in C notation,
"gt", "lt", "eq", "ne" in shell sh notation and "greater",
"less", "equal", "notequal" in human readable form (if not
specified, default is EQUAL).
I<value> is either an integer or a real number (except for
CHILDREN). For CPU, TOTALCPU, MEMORY and TOTALMEMORY you need to
specify a I<unit>. This could be "%" or if applicable "B" (Byte),
"kB" (1024 Byte), "MB" (1024 KiloByte) or "GB" (1024 MegaByte).
I<action> is a choice of "ALERT", "RESTART", "START", "STOP",
"EXEC" or "UNMONITOR".
To calculate the cycles, a counter is raised whenever the
expression above is true and it is lowered whenever it is false
(but not below 0). All counters are reset in case of a restart.
The following is an example to check that the CPU usage of a
service is not going beyond 50% during five poll cycles. If it
does, Monit will restart the service:
if cpu is greater than 50% for 5 cycles then restart
See also the example section below.
=head2 FILE CHECKSUM TESTING
The checksum statement may only be used in a file service
entry. If specified in the control file, Monit will compute
a md5 or sha1 checksum for a file.
The checksum test in constant form is used to verify that a
file does not change. Syntax (keywords are in capital):
=over 4
=item IF FAILED [MD5|SHA1] CHECKSUM [EXPECT checksum]
[[<X>] <Y> CYCLES] THEN action
[ELSE IF SUCCEEDED [[<X>] <Y> CYCLES] THEN action]
=back
The checksum test in variable form is used to watch for
file changes. Syntax (keywords are in capital):
=over 4
=item IF CHANGED [MD5|SHA1] CHECKSUM [[<X>] <Y> CYCLES]
THEN action
=back
The choice of MD5 or SHA1 is optional. MD5 features a 256 bit
and SHA1 a 320 bit checksum. If this option is omitted Monit
tries to guess the method from the EXPECT string or uses MD5 as
default.
I<expect> is optional and if used it specifies a md5 or sha1
string Monit should expect when testing a file's checksum. If
I<expect> is used, Monit will not compute an initial checksum for
the file, but instead use the string you submit. For example:
if failed checksum and
expect the sum 8f7f419955cefa0b33a2ba316cba3659
then alert
You can, for example, use the GNU utility I<md5sum(1)> or
I<sha1sum(1)> to create a checksum string for a file and
use this string in the expect-statement.
I<action> is a choice of "ALERT", "RESTART", "START", "STOP",
"EXEC" or "UNMONITOR".
The checksum statement in variable form may be used to check a
file for changes and if changed, do a specified action. For
instance to reload a server if its configuration file was
changed. The following illustrates this for the apache web
server:
check file httpd.conf path /usr/local/apache/conf/httpd.conf
if changed sha1 checksum
then exec "/usr/local/apache/bin/apachectl graceful"
If you plan to use the checksum statement for security reasons,
(a very good idea, by the way) and to monitor a file or files
which should not change, then please use the constant form and
also read the DEPENDENCY TREE section below to see a detailed
example on how to do this properly.
Monit can also test the checksum for files on a remote host via
the HTTP protocol. See the CONNECTION TESTING section below.
=head2 TIMESTAMP TESTING
The timestamp statement may only be used in a file, fifo or
directory service entry.
The timestamp test in constant form is used to verify various
timestamp conditions. Syntax (keywords are in capital):
=over 4
=item IF TIMESTAMP [[operator] value [unit]] [[<X>] <Y> CYCLES]
THEN action
[ELSE IF SUCCEEDED [[<X>] <Y> CYCLES] THEN action]
=back
The timestamp statement in variable form is simply to test an
existing file or directory for timestamp changes and if changed,
execute an action. Syntax (keywords are in capital):
=over 4
=item IF CHANGED TIMESTAMP [[<X>] <Y> CYCLES] THEN action
=back
I<operator> is a choice of "<", ">", "!=", "==" in C notation,
"GT", "LT", "EQ", "NE" in shell sh notation and "GREATER",
"LESS", "EQUAL", "NOTEQUAL" in human readable form (if not
specified, default is EQUAL).
I<value> is a time watermark.
I<unit> is either "SECOND", "MINUTE", "HOUR" or "DAY" (it is also
possible to use "SECONDS", "MINUTES", "HOURS", or "DAYS").
I<action> is a choice of "ALERT", "RESTART", "START", "STOP",
"EXEC" or "UNMONITOR".
The variable timestamp statement is useful for checking a file
for changes and then execute an action. This version was written
particularly with configuration files in mind. For instance, if
you monitor the apache web server you can use this statement to
reload apache if the I<httpd.conf> (apache's configuration file)
was changed. Like so:
check file httpd.conf with path /usr/local/apache/conf/httpd.conf
if changed timestamp
then exec "/usr/local/apache/bin/apachectl graceful"
The constant timestamp version is useful for monitoring systems
able to report its state by changing the timestamp of certain
state files. For instance the I<iPlanet Messaging server stored
process> system updates the timestamp of the following files:
o stored.ckp
o stored.lcu
o stored.per
If a task should fail, the system keeps the timestamp. To report
stored problems you can use the following statements:
check file stored.ckp with path /msg-foo/config/stored.ckp
if timestamp > 1 minute then alert
check file stored.lcu with path /msg-foo/config/stored.lcu
if timestamp > 5 minutes then alert
check file stored.per with path /msg-foo/config/stored.per
if timestamp > 1 hour then alert
As mentioned above, you can also use the timestamp statement for
monitoring directories for changes. If files are added or removed
from a directory, its timestamp is changed:
check directory mydir path /foo/directory
if timestamp > 1 hour then alert
or
check directory myotherdir path /foo/secure/directory
if timestamp < 1 hour then alert
The following example is a hack for restarting a process after a
certain time. Sometimes this is a necessary workaround for some
third-party applications, until the vendor fix a problem:
check file server.pid path /var/run/server.pid
if timestamp > 7 days
then exec "/usr/local/server/restart-server"
=head2 FILE SIZE TESTING
The size statement may only be used in a check file service
entry. If specified in the control file, Monit will compute
a size for a file.
The size test in constant form is used to verify various size
conditions. Syntax (keywords are in capital):
=over 4
=item IF SIZE [[operator] value [unit]] [[<X>] <Y> CYCLES]
THEN action
[ELSE IF SUCCEEDED [[<X>] <Y> CYCLES] THEN action]
=back
The size statement in variable form is simply to test an existing
file for size changes and if changed, execute an action. Syntax
(keywords are in capital):
=over 4
=item IF CHANGED SIZE [[<X>] <Y> CYCLES] THEN action
=back
I<operator> is a choice of "<", ">", "!=", "==" in C notation,
"GT", "LT", "EQ", "NE" in shell sh notation and "GREATER",
"LESS", "EQUAL", "NOTEQUAL" in human readable form (if not
specified, default is EQUAL).
I<value> is a size watermark.
I<unit> is a choice of "B","KB","MB","GB" or long alternatives
"byte", "kilobyte", "megabyte", "gigabyte". If it is not
specified, "byte" unit is assumed by default.
I<action> is a choice of "ALERT", "RESTART", "START", "STOP",
"EXEC" or "UNMONITOR".
The variable size test form is useful for checking a file for
changes and send an alert or execute an action. Monit will
register the size of the file at startup and monitor the file for
changes. As soon as the value changes, Monit will perform the
specified action, reset the registered value to the new value and
continue monitoring and test if the size changes again.
One example of use for this statement is to conduct security
checks, for instance:
check file su with path /bin/su
if changed size then exec "/sbin/ifconfig eth0 down"
which will "cut the cable" and stop a possible intruder from
compromising the system further. This test is just one of many
you may use to increase the security awareness on a system. If
you plan to use Monit for security reasons we recommend that you
use this test in combination with other supported tests like
checksum, timestamp, and so on.
The constant form of this test can be useful in similar or
different contexts. It can, for instance, be used to test if a
certain file size was exceeded and then alert you or Monit may
execute a certain action specified by you. An example is to use
this statement to rotate log files after they have reached a
certain size or to check that a database file does not grow
beyond a specified threshold.
To rotate a log file:
check file myapp.log with path /var/log/myapp.log
if size > 50 MB then
exec "/usr/local/bin/rotate /var/log/myapp.log myapp"
where /usr/local/bin/rotate may be a simple script, such as:
#/bin/bash
/bin/mv $1 $1.`date +%y-%m-%d`
/usr/bin/pkill -HUP $2
Or you may use this statement to trigger the logrotate(8)
program, to do an "emergency" rotate. Or to send an alert if a
file becomes a known bottleneck if it grows behind a certain size
because of limits in a database engine:
check file mydb with path /data/mydatabase.db
if size > 1 GB then alert
This is a more restrictive form of the first example where the
size is explicitly defined (note that the real su size is system
dependent):
check file su with path /bin/su
if size != 95564 then exec "/sbin/ifconfig eth0 down"
=head2 FILE CONTENT TESTING
The match statement allows you to test the content of a text file
by using regular expressions. This is a great feature if you need
to periodically test files, such as log files, for certain
patterns. If a pattern match, Monit defaults to raise an alert,
other actions are also possible.
The syntax (keywords in capital) for using this test is:
=over 4
=item IF [NOT] MATCH {regex|path} [[<X>] <Y> CYCLES] THEN action
=back
I<regex> is a string containing the extended regular expression.
See also regex(7).
I<path> is an absolute path to a file containing extended
regular expression on every line. See also regex(7).
I<action> is a choice of "ALERT", "RESTART", "START", "STOP",
"EXEC" or "UNMONITOR".
You can use the I<NOT> statement to invert a match.
The content is only being checked every cycle. If content is
being added and removed between two checks they are unnoticed.
On startup the read position is set to the end of the file
and Monit continue to scan to the end of file on each cycle.
But if the file size should decrease or inode change the read
position is set to the start of the file.
Only lines ending with a newline character are inspected. Thus,
lines are being ignored until they have been completed with this
character. Also note that only the first 511 characters of a line
are inspected.
=over 4
=item IGNORE [NOT] MATCH {regex|path}
=back
Lines matching an I<IGNORE> are not inspected during later
evaluations. I<IGNORE MATCH> has always precedence over
I<IF MATCH>.
All I<IGNORE MATCH> statements are evaluated first, in the
order of their appearance. Thereafter, all the I<IF MATCH>
statements are evaluated.
A real life example might look like this:
check file syslog with path /var/log/syslog
ignore match
"^\w{3} [ :0-9]{11} [._[:alnum:]-]+ monit\[[0-9]+\]:"
ignore match /etc/monit/ignore.regex
if match
"^\w{3} [ :0-9]{11} [._[:alnum:]-]+ mrcoffee\[[0-9]+\]:"
if match /etc/monit/active.regex then alert
=head2 FILESYSTEM FLAGS TESTING
Monit can test the flags of a filesystem for changes. This test
is implicit and Monit will send alert in case of failure by
default.
This test is useful for detecting changes of the filesystem flags
such as when the filesystem became read-only based on disk errors
or the mount flags were changed (such as nosuid). Each platform
provides different set of flags. POSIX define the RDONLY and
NOSUID flags which should work on all platforms. Some platforms
(such as FreeBSD) has additonal flags.
The syntax for the fsflags statement is:
=over 4
=item IF CHANGED FSFLAGS [[<X>] <Y> CYCLES] THEN action
=back
I<action> is a choice of "ALERT", "RESTART", "START", "STOP",
"EXEC" or "UNMONITOR".
Example:
check filesystem rootfs with path /
if changed fsflags then exec "/my/script"
alert root@localhost
=head2 SPACE TESTING
Monit can test file systems for space usage. This test may
only be used within a check filesystem service entry in the
Monit control file.
Monit will check a filesystem's total space usage. If you only
want to check available space for non-superuser, you must set the
watermark appropriately (i.e. total space minus reserved blocks
for the superuser).
You can obtain (and set) the superuser's reserved blocks size,
for example by using the tune2fs utility on Linux. On Linux 5% of
available blocks are reserved for the superuser by default. On
solaris 10% of the blocks are reserved. You can also use tunefs
on solaris to change values on a live filesystem.
The full syntax for the space statement is:
=over 4
=item IF SPACE operator value unit [[<X>] <Y> CYCLES] THEN action
[ELSE IF SUCCEEDED [[<X>] <Y> CYCLES] THEN action]
=back
I<operator> is a choice of "<",">","!=","==" in c notation, "gt",
"lt", "eq", "ne" in shell sh notation and "greater", "less",
"equal", "notequal" in human readable form (if not specified,
default is EQUAL).
I<unit> is a choice of "B","KB","MB","GB", "%" or long
alternatives "byte", "kilobyte", "megabyte", "gigabyte",
"percent".
I<action> is a choice of "ALERT", "RESTART", "START", "STOP",
"EXEC" or "UNMONITOR".
=head2 INODE TESTING
If supported by the file-system, you can use Monit to test
for inodes usage. This test may only be used within a check
filesystem service entry in the Monit control file.
If the filesystem becomes unavailable, Monit will call the
service's registered start method, if it is defined and if Monit
is running in active mode. If Monit runs in passive mode or the
start methods is not defined, Monit will just send an error
alert.
The syntax for the inode statement is:
=over 4
=item IF INODE(S) operator value [unit] [[<X>] <Y> CYCLES]
THEN action
[ELSE IF SUCCEEDED [[<X>] <Y> CYCLES] THEN action]
=back
I<operator> is a choice of "<",">","!=","==" in c notation, "gt",
"lt", "eq", "ne" in shell sh notation and "greater", "less",
"equal", "notequal" in human readable form (if not specified,
default is EQUAL).
I<unit> is optional. If not specified, the value is an absolute
count of inodes. You can use the "%" character or the longer
alternative "percent" as a unit.
I<action> is a choice of "ALERT", "RESTART", "START", "STOP",
"EXEC" or "UNMONITOR".
=head2 PERMISSION TESTING
Monit can monitor the permission of file objects. This test may
only be used within a file, fifo, directory or filesystem service
entry in the Monit control file.
The syntax for the permission statement is:
=over 4
=item IF FAILED PERM(ISSION) octalnumber [[<X>] <Y> CYCLES]
THEN action
[ELSE IF SUCCEEDED [[<X>] <Y> CYCLES] THEN action]
=back
I<octalnumber> defines permissions for a file, a directory or a
filesystem as four octal digits (0-7). Valid range: 0000 - 7777 (you
can omit the leading zeros, Monit will add the zeros to the left
thus for example "640" is valid value and matches "0640").
I<action> is a choice of "ALERT", "RESTART", "START", "STOP",
"EXEC" or "UNMONITOR".
The web interface will show a permission warning if the test
failed.
We recommend that you use the UNMONITOR action in a permission
statement. The rationale for this feature is security and that
Monit does not start a possible cracked program or script.
Example:
check file monit.bin with path "/usr/local/bin/monit"
if failed permission 0555 then unmonitor
If the test fails, Monit will simply send an alert and stop
monitoring the file and propagate an unmonitor action upward in
a depend tree.
=head2 UID TESTING
Monit can monitor the owner user id (uid) of a file object.
This test may only be used within a check - file, fifo,
directory or filesystem service entry in the Monit control
file.
The syntax for the uid statement is:
=over 4
=item IF FAILED UID user [[<X>] <Y> CYCLES] THEN action
[ELSE IF SUCCEEDED [[<X>] <Y> CYCLES] THEN action]
=back
I<user> defines a user id either in numeric or in string form.
I<action> is a choice of "ALERT", "RESTART", "START", "STOP",
"EXEC" or "UNMONITOR".
The web interface will show a uid warning if the test should
fail.
We recommend that you use the UNMONITOR action in a uid
statement. The rationale for this feature is security and that
Monit does not start a possible cracked program or script.
Example:
check file passwd with path /etc/passwd
if failed uid root then unmonitor
If the test fails, Monit will simply send an alert and stop
monitoring the file and propagate an unmonitor action upward in
a depend tree.
=head2 GID TESTING
Monit can monitor the owner group id (gid) of file objects. This
test may only be used within a file, fifo, directory or
filesystem service entry in the Monit control file.
The syntax for the gid statement is:
=over 4
=item IF FAILED GID user [[<X>] <Y> CYCLES] THEN action
[ELSE IF SUCCEEDED [[<X>] <Y> CYCLES] THEN action]
=back
I<user> defines a group id either in numeric or in string form.
I<action> is a choice of "ALERT", "RESTART", "START", "STOP",
"EXEC" or "UNMONITOR".
The web interface will show a gid warning if the test should
fail.
We recommend that you use the UNMONITOR action in a gid
statement. The rationale for this feature is security and that
Monit does not start a possible cracked program or script.
Example:
check file shadow with path /etc/shadow
if failed gid root then unmonitor
If the test fails, Monit will simply send an alert and stop
monitoring the file and propagate an unmonitor action upward in
a depend tree.
=head2 PID TESTING
Monit can test the process identification number (pid) of a
process for changes. This test is implicit and Monit will send a
alert in the case of failure by default.
The syntax for the pid statement is:
=over 4
=item IF CHANGED PID [[<X>] <Y> CYCLES] THEN action
=back
I<action> is a choice of "ALERT", "RESTART", "START", "STOP",
"EXEC" or "UNMONITOR".
This test is useful to detect possible process restarts which has
occurred in the timeframe between two Monit testing cycles. In
the case that the restart was fast and the process provides
expected service (i.e. all tests succeeded) you will be notified
that the process was replaced.
For example sshd daemon can restart very quickly, thus if someone
changes its configuration and do sshd restart outside of Monit's
control you will be notified that the process was replaced by a
new instance (or you can optionally do some other action such as
preventively stop sshd).
Another example is a MySQL Cluster which has its own watchdog
with process restart ability. You can use Monit for redundant
monitoring.
Example:
check process sshd with pidfile /var/run/sshd.pid
if changed pid then exec "/my/script"
=head2 PPID TESTING
Monit can test the process parent process identification number
(ppid) of a process for changes. This test is implicit and Monit
will send alert in the case of failure by default.
The syntax for the ppid statement is:
=over 4
=item IF CHANGED PPID [[<X>] <Y> CYCLES] THEN action
=back
I<action> is a choice of "ALERT", "RESTART", "START", "STOP",
"EXEC" or "UNMONITOR".
This test is useful for detecting changes of a process parent.
Example:
check process myproc with pidfile /var/run/myproc.pid
if changed ppid then exec "/my/script"
=head2 UPTIME TESTING
The uptime statement may only be used in a check process service
entry. If specified in the control file, Monit will test the
process uptime.
Syntax (keywords are in capital):
=over 4
=item IF UPTIME [[operator] value [unit]] [[<X>] <Y> CYCLES]
THEN action
[ELSE IF SUCCEEDED [[<X>] <Y> CYCLES] THEN action]
=back
I<operator> is a choice of "<", ">", "!=", "==" in C notation,
"GT", "LT", "EQ", "NE" in shell sh notation and "GREATER",
"LESS", "EQUAL", "NOTEQUAL" in human readable form (if not
specified, default is EQUAL).
I<value> is a uptime watermark.
I<unit> is either "SECOND", "MINUTE", "HOUR" or "DAY" (it is also
possible to use "SECONDS", "MINUTES", "HOURS", or "DAYS").
I<action> is a choice of "ALERT", "RESTART", "START", "STOP",
"EXEC" or "UNMONITOR".
Example of restarting the process if the uptime exceeded 3 days:
check process myapp with pidfile /var/run/myapp.pid
start program = "/etc/init.d/myapp start"
stop program = "/etc/init.d/myapp stop"
if uptime > 3 days then restart
=head2 CONNECTION TESTING
Monit is able to perform connection testing via networked
ports or via Unix sockets. A connection test may only be
used within a check process or within a check host service
entry in the Monit control file.
If a service listens on one or more sockets, Monit can connect to
the port (using either tcp or udp) and verify that the service
will accept a connection and that it is possible to write and
read from the socket. If a connection is not accepted or if there
is a problem with socket i/o, Monit will assume that something is
wrong and execute a specified action. If Monit is compiled with
openssl, then ssl based network services can also be tested.
The full syntax for the statement used for connection testing is
as follows (keywords are in capital and optional statements in
[brackets]),
=over 4
=item IF FAILED [host] port [type]
[protocol|{send/expect}+] [timeout] [retry] [[<X>] <Y> CYCLES]
THEN action
[ELSE IF SUCCEEDED [[<X>] <Y> CYCLES] THEN action]
=back
or for Unix sockets,
=over 4
=item IF FAILED [unixsocket] [type]
[protocol|{send/expect}+] [timeout] [retry] [[<X>] <Y> CYCLES]
THEN action
[ELSE IF SUCCEEDED [[<X>] <Y> CYCLES] THEN action]
=back
B<host:HOST hostname>. Optionally specify the host to connect to.
If the host is not given then localhost is assumed if this test
is used inside a process entry. If this test was used inside a
remote host entry then the entry's remote host is assumed.
Although I<host> is intended for testing name based virtual host
in a HTTP server running on local or remote host, it does allow
the connection statement to be used to test a server running on
another machine. This may be useful; For instance if you use
Apache httpd as a front-end and an application-server as the
back-end running on another machine, this statement may be used
to test that the back-end server is running and if not raise an
alert.
B<port:PORT number>. The port number to connect to
B<unixsocket:UNIXSOCKET PATH>. Specifies the path to a Unix
socket. Servers based on Unix sockets always run on the local
machine and do not use a port.
B<type:TYPE {TCP|UDP|TCPSSL}>. Optionally specify the socket type
Monit should use when trying to connect to the port. The
different socket types are; TCP, UDP or TCPSSL, where TCP is a
regular stream based socket, UDP is a datagram socket and TCPSSL
specifies that Monit should use a TCP socket with SSL when
connecting to a port. The default socket type is TCP. If TCPSSL
is used you may optionally specify the SSL/TLS protocol to be
used and the md5 sum of the server's certificate. The TCPSSL
options are:
TCPSSL [SSLAUTO|SSLV2|SSLV3|TLSV1] [CERTMD5 md5sum]
B<proto(col):PROTO {protocols}>. Optionally specify the protocol
Monit should speak when a connection is established. At the
moment Monit knows how to speak:
I<APACHE-STATUS>
I<DNS>
I<DWP>
I<FTP>
I<GPS>
I<HTTP>
I<IMAP>
I<CLAMAV>
I<LDAP2>
I<LDAP3>
I<LMTP>
I<MEMCACHE>
I<MYSQL>
I<NNTP>
I<NTP3>
I<POP>
I<POSTFIX-POLICY>
I<RADIUS>
I<RDATE>
I<RSYNC>
I<SIP>
I<SMTP>
I<SSH>
I<TNS>
I<PGSQL>
If you have compiled Monit with ssl support, Monit can also speak
the SSL variants such as:
I<HTTPS>
I<FTPS>
I<POPS>
I<IMAPS>
To use the SSL protocol support you need to define the socket as
SSL and use the general protocol name (for example in the case of
HTTPS) :
TYPE TCPSSL PROTOCOL HTTP
If the server's protocol is not found in this list, simply do not
specify the protocol and Monit will utilize a default test,
including test if it is possible to read and write to the
port. This default test is in most cases more than good enough to
deduce if the server behind the port is up or not.
The protocol statement is:
PROTO(COL) {name}
The HTTP protocol supports in addition:
=over 4
=item * REQUEST
=item * HOSTHEADER
=item * CHECKSUM
=back
PROTO(COL) HTTP [REQUEST {"/path"} [with CHECKSUM checksum] [with HOSTHEADER "string"]
The Host header option can be used to explicit specify the HTTP
host header in the request. If not used, Monit will use the
hostname or IP-address of the host as specified in the statement.
Specifying a host header is useful if you want to connect to the
host using an IP-address, and the web-server handle name based
virtual hosts. Examples:
if failed host 192.168.1.100 port 8080 protocol http
and request '/testing' hostheader 'example.com'
with timeout 20 seconds for 2 cycles
then alert
In addition to the standard protocols, the I<APACHE-STATUS>
protocol is a test of a specific server type, rather than a
generic protocol. Server performance is examined using the status
page generated by Apache's mod_status, which is expected to be at
its default address of http://www.example.com/server-status.
Currently the I<APACHE-STATUS> protocol examines the percentage
of Apache child processes which are
o logging (loglimit)
o closing connections (closelimit)
o performing DNS lookups (dnslimit)
o in keepalive with a client (keepalivelimit)
o replying to a client (replylimit)
o receiving a request (requestlimit)
o initialising (startlimit)
o waiting for incoming connections (waitlimit)
o gracefully closing down (gracefullimit)
o performing cleanup procedures (cleanuplimit)
Each of these quantities can be compared against a value relative
to the total number of active Apache child processes. If the
comparison expression is true the chosen action is performed.
The apache-status protocol statement is formally defined as
(keywords in uppercase):
PROTO(COL) {limit} OP PERCENT [OR {limit} OP PERCENT]*
where {limit} is one or more of: loglimit, closelimit, dnslimit,
keepalivelimit, replylimit, requestlimit, startlimit, waitlimit
gracefullimit or cleanuplimit. The operator OP is one of:
[<|=|>].
You can combine all of these test into one expression or you can
choose to test a certain limit. If you combine the limits you
must or' them together using the OR keyword.
Here's an example were we test for a loglimit more than 10
percent, a dnslimit over 25 percent and a wait limit less than 20
percent of processes. See also more examples below in the example
section.
protocol apache-status
loglimit > 10% or
dnslimit > 50% or
waitlimit < 20%
then alert
Obviously, do not use this test unless the httpd server you are
testing is Apache Httpd and mod_status is activated on the
server.
B<send/expect: {SEND|EXPECT} "string" ...>. If Monit does not
support the protocol spoken by the server, you can write your own
protocol-test using I<send> and I<expect> strings. The I<SEND>
statement sends a string to the server port and the I<EXPECT>
statement compares a string read from the server with the string
given in the expect statement. If your system supports POSIX
regular expressions, you can use regular expressions in the
expect string, see regex(7) to learn more about the types of
regular expressions you can use in an expect string. Otherwise
the string is used as it is. The send/expect statement is:
[{SEND|EXPECT} "string"]+
Note that Monit will send a string as it is, and you B<must>
remember to include CR and LF in the string sent to the server if
the protocol expect such characters to terminate a string (most
text based protocols used over Internet does). Likewise monit
will read up to 256 bytes from the server and use this string
when comparing the expect string. If the server sends strings
terminated by CRLF, (i.e. "\r\n") you I<may> remember to add the
same terminating characters to the string you expect from the
server.
As mentioned above, Monit limits the expect input to 255 bytes.
You can override the default value by using this set statement at
the top of the Monit configuration file:
SET EXPECTBUFFER <number> ["b"|"kb"|"mb"]
For example, to set the expect buffer to read 10 kilobytes:
set expectbuffer 10 kb
Note, if you want to test the number of bytes returned from the
server you need to work around a bound check limit in POSIX
regex. You cannot use something like expect ".{5000}" as the max
number in a boundary check usually is {255}. However this should
work, expect "(.{250}){20}"
You can use non-printable characters in a send string if needed.
Use the hex notation, \0xHEXHEX to send any char in the range
\0x00-\0xFF, that is, 0-255 in decimal. This may be useful when
testing some network protocols, particularly those over UDP. For
example, to test a quake 3 server you can use the following,
send "\0xFF\0xFF\0xFF\0xFFgetstatus"
expect "sv_floodProtect|sv_maxPing"
Finally, send/expect can be used with any socket type, such as
TCP sockets, UNIX sockets and UDP sockets.
B<timeout:with TIMEOUT x SECONDS>. Optionally specifies the
connect and read timeout for the connection. If Monit cannot
connect to the server within this time it will assume that the
connection failed and execute the specified action. The default
connect timeout is 5 seconds.
B<retry:RETRY x>. Optionally specifies the number of consecutive
retries within the same testing cycle in the case that the
connection failed. The default is fail on first error.
I<action> is a choice of "ALERT", "RESTART", "START", "STOP",
"EXEC" or "UNMONITOR".
=head4 Connection testing using the URL notation
You can test a HTTP server using the compact URL syntax. This
test also allow you to use POSIX regular expressions to test the
content returned by the HTTP server.
The full syntax for the URL statement is as follows (keywords are
in capital and optional statements in [brackets]):
IF FAILED URL URL-spec
[CONTENT {==|!=} "regular-expression"]
[TIMEOUT number SECONDS] [[<X>] <Y> CYCLES]
THEN action
[ELSE IF SUCCEEDED [[<X>] <Y> CYCLES] THEN action]
Where URL-spec is an URL on the standard form as specified in RFC
2396:
<protocol>://<authority><path>?<query>
Here is an example of an URL where all components are used:
http://user:password@www.foo.bar:8080/document/?querystring#ref
If a username and password is included in the URL Monit will
attempt to login at the server using B<Basic Authentication>.
Testing the content returned by the server is optional. If used,
you can test if the content B<match> or does B<not match> a
regular expression. Here's an example on how the URL statement
can be used in a I<check service>:
check host FOO with address www.foo.bar
if failed (url http://user:password@www.foo.bar:8080/login?querystring
and content == 'up')
then ...
Note that the content option extends the URL by the expected data
and does not act as standalone failure specification. The syntax is
"if failed (<URL> and <content>)".
Monit will look at the content-length header returned by the
server and download this amount before testing the content. That
is, if the content-length is more than 1Mb or this header is not
set by the server Monit will default to download up to 1 Mb and
not more.
Only the http(s) protocol is supported in an URL statement. If
the protocol is B<https> Monit will use SSL when connecting to
the server.
=head4 Remote host ping test
In addition Monit can perform ICMP Echo tests in remote host
checks. The icmp test may only be used in a check host entry and
Monit must run with super user privileges, that is, the root user
must run monit. The reason is that the icmp test utilize a raw
socket to send the icmp packet and only the super user is allowed
to create a raw socket.
The full syntax for the ICMP Echo statement used for ping testing
is as follows (keywords are in capital and optional statements in
[brackets]):
IF FAILED ICMP TYPE ECHO
[COUNT number] [WITH] [TIMEOUT number SECONDS]
[[<X>] <Y> CYCLES]
THEN action
[ELSE IF SUCCEEDED [[<X>] <Y> CYCLES] THEN action]
The rules for action and timeout are the same as those mentioned
above in the CONNECTION TESTING section. The count parameter
specifies how many consecutive echo requests will be send to the
host in one cycle. In the case that no reply came within timeout
frame, Monit reports error. When at least one reply was received,
the test will pass. Monit sends by default three echo requests in
one cycle to prevent the random packet loss from generating false
alarm (i.e. up to 66% packet loss is tolerated). You can set the
count option to a value between 1 and 20, which can serve as an
error ratio. For example if you require 100% ping success, set
the count to 1 (i.e. just one request will be sent, and if the
packet was lost an error will be reported).
An icmp ping test is useful for testing if a host is up, before
testing ports at the host. If an icmp ping test is used in a
check host entry, this test is run first and if the ping test
should fail we assume that the connection to the host is down and
Monit does I<not> continue to test any ports. Here's an example:
check host xyzzy with address xyzzy.org
if failed icmp type echo count 5 with timeout 15 seconds
then alert
if failed port 80 proto http then alert
if failed port 443 type TCPSSL proto http then alert
alert foo@bar
In this case, if the icmp test should fail you will get I<one>
alert and only one alert as long as the host is down, and equally
important, Monit will I<not> test port 80 and port 443. Likewise
if the icmp ping test should succeed (again) Monit will continue
to test both port 80 and 443.
Keep in mind though that some firewalls can block icmp packages
and thus render the test useless.
=head4 Examples
To check a port connection and receive an alert if Monit cannot
connect to the port, use the following statement:
if failed port 80 then alert
In this case the machine in question is assumed to be the default
host. For a process entry it's I<localhost> and for a remote host
entry it's the I<address> of the remote host. Monit will conduct
a tcp connection to the host at port 80 and use tcp by default.
If you want to connect with udp, you can specify this after the
port-statement;
if failed port 53 type udp protocol dns then alert
Monit will stop trying to connect to the port after 5 seconds and
assume that the server behind the port is down. You may increase
or decrease the connect timeout by explicit add a connection
timeout. In the following example the timeout is increased to 15
seconds and if Monit cannot connect to the server within 15
seconds the test will fail and an alert message is sent.
if failed port 80 with timeout 15 seconds then alert
If a server is listening to a Unix socket the following statement
can be used:
if failed unixsocket /var/run/sophie then alert
A Unix socket is used by some servers for fast (interprocess)
communication on localhost only. A Unix socket is specified by a
path and in the example above the path, /var/run/sophie,
specifies a Unix socket.
If your machine answers for several virtual hosts you can prefix
the port statement with a host-statement like so:
if failed host www.sol.no port 80 then alert
if failed host 80.69.226.133 port 443 then alert
if failed host kvasir.sol.no port 80 then alert
And as mentioned above, if you do not specify a host-statement,
I<localhost> or I<address> is assumed.
Monit also knows how to speak some of the more popular Internet
protocols. So, besides testing for connections, Monit can also
speak with the server in question to verify that the server
works. For example, the following is used to test a http server:
if failed host www.tildeslash.com port 80 proto http
then restart
Some protocols also support a request statement. This statement
can be used to ask the server for a special document entity.
Currently B<only> the I<HTTP> protocol module supports the
request statement, such as:
if failed host www.myhost.com port 80 protocol http
and request "/data/show.php?a=b&c=d"
then restart
The request must contain an URI string specifying a document from
the http server. The string will be URL encoded by Monit before
it sends the request to the http server, so it's okay to use URL
unsafe characters in the request. If the request statement isn't
specified, the default web server page will be requested.
You can override default Host header in HTTP request:
if failed host 192.168.1.100 port 80 protocol http
hostheader "example.com"
then alert
You can also test the checksum for documents returned by a http
server. You can use either MD5 sums:
if failed port 80 protocol http
and request "/page.html"
with checksum 8f7f419955cefa0b33a2ba316cba3659
then alert
Or you can use SHA1 sums:
if failed port 80 protocol http
and request "/page.html"
with checksum e428302e260e0832007d82de853aa8edf19cd872
then alert
Monit will compute a checksum (either MD5 or SHA1 is used,
depending on length of the hash) for the document (in the above
case, /page.html) and compare the computed checksum with the
expected checksum. If the sums does not match then the if-tests
action is performed, in this case alert. Note that Monit will
B<not> test the checksum for a document if the server does not
set the HTTP I<Content-Length> header. A HTTP server should set
this header when it server a static document (i.e. a file). A
server will often use chunked transfer encoding instead when
serving dynamic content (e.g. a document created by a CGI-script
or a Servlet), but to test the checksum for dynamic content is
not very useful. There are no limitation on the document size,
but keep in mind that Monit will use time to download the
document over the network so it's probably smart not to ask monit
to compute a checksum for documents larger than 1Mb or so,
depending on you network connection of course. Tip; If you get a
checksum error even if the document has the correct sum, the
reason may be that the download timed out. In this case, explicit
set a longer timeout than the default 5 seconds.
As mentioned above, if the server protocol is not supported by
Monit you can write your own protocol test using send/expect
strings. Here we show a protocol test using send/expect for an
imaginary "Ali Baba and the Forty Thieves" protocol:
if failed host cave.persia.ir port 4040
send "Open, Sesame!\r\n"
expect "Please enter the cave\r\n"
send "Shut, Sesame!\r\n"
expect "See you later [A-Za-z ]+\r\n"
then restart
The I<TCPSSL> statement can optionally test the md5 sum of the
server's certificate. You must state the md5 certificate string
you expect the server to deliver and upon a connect to the
server, the server's actual md5 sum certificate string is tested.
Any other symbol but [A-Fa-f0-9] is being ignored in that sting.
Thus it is possible to copy and paste the output of e.g. openssl.
If they do not match, the connection test fails. If the ssl
version handshake does not work properly you can also force a
specific ssl version, as we demonstrate in this example:
if failed host shop.sol.no port 443
type TCPSSL SSLV3 # Force Monit to use ssl version 3
# We expect the server to return this md5 certificate sum
# as either 12-34-56-78-90-AB-CD-EF-12-34-56-78-90-AB-CD-EF
# or e.g. 1234567890ABCDEF1234567890ABCDEF
# or e.g. 1234567890abcdef1234567890abcdef
# what ever come in more handy (see text above)
CERTMD5 12-34-56-78-90-AB-CD-EF-12-34-56-78-90-AB-CD-EF
protocol http
then restart
Here's an example where a connection test is used inside a
process entry:
check process apache with pidfile /var/run/apache.pid
start program = "/etc/init.d/httpd start"
stop program = "/etc/init.d/httpd stop"
if failed host www.tildeslash.com port 80 then restart
Here, a connection test is used in a remote host entry:
check host up2date with address ftp.redhat.com
if failed port 21 and protocol ftp then alert
Since we did not explicit specify a host in the above test, monit
will connect to port 21 at ftp.redhat.com. Apropos, the host
address can be specified as a dotted IP address string or as
hostname in the DNS. The following is exactly[*] the same test,
but here an ip address is used instead:
check host up2date with address 66.187.232.30
if failed port 21 and protocol ftp then alert
[*] Well, not quite, since we specify an ip-address directly we
will bypass any DNS round-robin setup, but that's another story.
=head4 Testing the SIP protocol
The SIP protocol is used by communication platform servers such
as Asterisk and FreeSWITCH.
The SIP test is similar to the other protocol tests, but in
addition allows extra optional parameters.
=over 4
=item IF FAILED [host] [port] [type] PROTOCOL sip
[AND] [TARGET valid@uri] [AND] [MAXFORWARD n]
THEN action
[ELSE IF SUCCEEDED [[<X>] <Y> CYCLES] THEN action]
=back
TARGET :
you may specify an alternative recipient for the message,
by adding a valid sip uri after this keyword.
MAXFORWARD :
Limit the number of proxies or gateways that can forward the
request to the next server. It's value is an integer in the range
0-255, set by default to 70. If max-forward = 0, the next server
may respond 200 OK (test succeeded) or send a 483 Too Many Hops
(test failed)
SIP examples:
check host openser_all with address 127.0.0.1
if failed port 5060 type udp protocol sip
with target "localhost:5060" and maxforward 6
then alert
If sips is supported, that is, sip over ssl, specify tcpssl as
the connection type.
check host fwd.pulver.com with address fwd.pulver.com
if failed port 5060 type tcpssl protocol SIP
and target 613@fwd.pulver.com maxforward 10
then alert
For more examples, see the example section below.
=head4 Testing the RADIUS protocol
The RADIUS test is similar to the other protocol tests, but in
addition allows extra optional parameters.
=over 4
=item IF FAILED [host] [port] [type] PROTOCOL radius [SECRET string] THEN action
[ELSE IF SUCCEEDED [[<X>] <Y> CYCLES] THEN action]
=back
SECRET:
you may specify an alternative secret, default is "testing123".
RADIUS example:
check process radiusd with pidfile /var/run/radiusd.pid
start program = "/etc/init.d/freeradius start"
stop program = "/etc/init.d/freeradius stop"
if failed host 127.0.0.1 port 1812 type udp protocol radius
secret testing123
then alert
if 5 restarts within 5 cycles then timeout
=head2 PROGRAM STATUS TESTING
You can check the exit status of a program or a script. This test
may only be used within a check program service entry in the Monit
control file.
An example:
check program myscript with path "/usr/local/bin/myscript.sh"
if status != 0 then alert
Monit will execute the program periodically and if the exit
status of the program does not match the expected result, Monit
can perform an action. In the example above, Monit will raise an
alert if the exit value of I<myscript> is different from 0. By
convention, 0 means the program exited normally.
Program checks are asynchronous. Meaning that Monit will not wait
for the program to exit, but instead, Monit will start the
program in the background and immediately continue checking the
next service entry in I<monitrc>. At the next cycle, Monit will
check if the program has finished and if so, collect the programs
exit status - if the status indicate a failure, Monit will raise
an alert message containing the program's error (stderr) output,
if any. If the program has not exited after the first cycle,
Monit will wait another cycle and so on. If the program is still
running after 5 minutes, Monit will kill it and generate a
program timeout event. It is possible to override the default
timeout (see the syntax below).
The asynchronous nature of the program check allows for
non-blocking behavior in the current Monit design, but it comes
with a side-effect: when the program has finished executing and
is waiting for Monit to collect the result, it becomes a
so-called "zombie" process. A zombie process does not consume
any system resources (only the PID remains in use) and it is
under Monit's control; The zombie process is removed from the
system as soon as Monit collects the exit status. This means that
every "check program" will be associated with either a running
process or a temporary zombie. This unwanted zombie side-effect
will be removed in a later release of Monit.
The syntax of the program status statement is:
=over 4
=item IF STATUS operator value [TIMEOUT <N> SECONDS] [[<X>] <Y> CYCLES] THEN action
[ELSE IF SUCCEEDED [[<X>] <Y> CYCLES] THEN action]
=back
I<operator> is a choice of "<",">","!=","==" in c notation, "gt",
"lt", "eq", "ne" in shell sh notation and "greater", "less",
"equal", "notequal" in human readable form (if not specified,
default is EQUAL).
I<action> is a choice of "ALERT", "RESTART", "START", "STOP",
"EXEC" or "UNMONITOR".
=head1 SERVICE POLL TIME
Services are checked in regular intervals given by the I<set
daemon n> statement. Checks are performed in the same order as
they are written in the I<.monitrc> file, except if dependencies
are setup between services, in which case the services hierarchy
may alternate the order of the checks.
It is possible to modify the check schedule using the I<every>
statement.
There are three variants:
=over 4
=item 1. custom interval based on poll cycle length multiple
EVERY [number] CYCLES
=item 2. test schedule based on cron-style string
EVERY [cron]
=item 3. do-not-test schedule based on cron-style string
NOT EVERY [cron]
=back
A cron-style string, consist of 5 fields separated with
white-space. All fields are required:
Name: | Allowed values: | Special characters:
---------------------------------------------------------------
Minutes | 0-59 | * - ,
Hours | 0-23 | * - ,
Day of month | 1-31 | * - ,
Month | 1-12 (1=jan, 12=dec) | * - ,
Day of week | 0-6 (0=sunday, 6=saturday) | * - ,
The special characters:
Character: | Description:
---------------------------------------------------------------
* (asterisk) | The asterisk indicates that the expression will
| match for all values of the field; e.g., using
| an asterisk in the 4th field (month) would
| indicate every month.
- (hyphen) | Hyphens are used to define ranges. For example,
| 8-9 in the hour field indicate between 8AM and
| 9AM. Note that range is from time1 until and
| including time2. That is, from 8AM and until
| 10AM unless minutes are set. Another example,
| 1-5 in the weekday field, specify from monday to
| friday (including friday).
, (comma) | Comma are used to specify a sequence. For example
| 17,18 in the day field indicate the 17th and 18th
| day of the month. A sequence can also include
| ranges. For example, using 1-5,0 in the weekday
| field indicate monday to friday and sunday.
Example 1: Check once per two cycles
check process nginx with pidfile /var/run/nginx.pid
every 2 cycles
Example 2: Check every workday 8AM-7PM
check program checkOracleDatabase with
path /var/monit/programs/checkoracle.pl
every "* 8-19 * * 1-5"
Example 3: Do not run the check in the backup window on
Sunday 0AM-3AM
check process mysqld with pidfile /var/run/mysqld.pid
not every "* 0-3 * * 0"
Limitations:
The current test scheduler is poll cycle based. When Monit starts
testing and the service test is constraint with the I<every cron>
statement, it checks whether the current time match the
cron-string pattern. If it does, the test is done, otherwise it
is skipped. The cron specification thus does not guarantee when
exactly the test will run - that depends on the default poll time
and the length of the testing cycle. In other words, we cannot
guarantee that Monit will run on a specific time. Therefor we
B<strongly> recommend to use an asterix in the minute field or at
minimum a range, e..g. 0-15. B<Never> use a specific minute as
Monit may not run on that minute.
We will address this limitation in a future release and convert
the test scheduler from serial polling into a parallel
non-blocking scheduler where checks are guaranteed to run on time
and with seconds resolution.
=head1 MONIT HTTPD
If specified in the control file, Monit will start a Monit daemon
with http support. From a Browser you can then start and stop
services, disable or enable service monitoring as well as view
the status of each service. Also, if Monit logs to its own file,
you can view the content of this logfile in a Browser.
The control file statement for starting a Monit daemon with http
support is a global set-statement:
=over 4
=item set httpd port 2812
=back
And you can use this URL, I<http://localhost:2812/>, to access
the daemon from a browser. The port number, in this case 2812,
can be any number that you are allowed to bind to.
If you have compiled Monit with openssl, you can also start the
httpd server with ssl support, using the following expression:
set httpd port 2812
ssl enable
pemfile /etc/certs/monit.pem
And you can use this URL, I<https://localhost:2812/>, to access
the Monit web server over an ssl encrypted connection.
The pemfile, in the example above, holds both the server's
private key and certificate. This file should be stored in a safe
place on the filesystem and should have strict permissions, that
is, no more than 0700.
In addition, if you want to check for client certificates you can
use the CLIENTPEMFILE statement. In this case, a connecting
client has to provided a certificate known by Monit in order to
connect. This file also needs to have all necessary CA
certificates. A configuration could look like:
set httpd port 2812
ssl enable
pemfile /etc/certs/monit.pem
clientpemfile /etc/certs/monit-client.pem
By default self signed client certificates are not allowed. If
you want to use a self signed certificate from a client it has to
be allowed explicitly with the ALLOWSELFCERTIFICATION statement.
For more information on how to use Monit with SSL and for more
information about certificates and generating pem files, please
consult the README.SSL file accompanying the software.
If you only want the http server to accept connect requests to
one host addresses you can specify the bind address either as an
IP number string or as a hostname. In the following example we
bind the http server to the loopback device. In other words the
http server will only be reachable from localhost:
set httpd port 2812 and use the address 127.0.0.1
or
set httpd port 2812 and use the address localhost
If you do not use the ADDRESS statement the http server will
accept connections on any/all local addresses.
It is possible to hide monit's httpd server version, which
usually is available in httpd header responses and in error
pages.
set httpd port 2812
...
signature {enable|disable}
Use I<disable> to hide the server signature - Monit will only
report its name (e.g. 'monit' instead of for example 'monit
4.2'). By default the version signature is enabled. It is worth
to stress that this option provides no security advantage and
falls into the "security through obscurity" category.
If you remove the httpd statement from the config file, monit
will stop the httpd server on configuration reload. Likewise if
you change the port number, Monit will restart the http server
using the new specified port number.
The status page displayed by the Monit web server is
automatically refreshed with the same poll time set for the monit
daemon.
B<Note:>
We strongly recommend that you start Monit with http support (and
bind the server to localhost, only, unless you are behind a
firewall). The built-in web-server is small and does not use much
resources, and more I<importantly>, Monit can use the http server
for interprocess communication between a Monit client and a monit
daemon.
For instance, you I<must> start a Monit daemon with http support
if you want to be able to use most of the available console
commands. I.e. 'Monit stop all', 'Monit start all' etc.
If a Monit daemon is running in the background we will ask the
daemon (via the HTTP protocol) to execute the above commands.
That is, the daemon is requested to start and stop the services.
This ensures that a daemon will not restart a service that you
requested to stop and that (any) timeout lock will be removed
from a service when you start it.
=head2 FIPS support
Monit built-in web-server supports the OpenSSL FIPS module.
To enable this mode, your OpenSSL library must first be built
with FIPS support. Then in the Monit control file, simply
add this I<set> statement at the top;
set fips
Note that the FIPS module may not be supported in the latest
version of OpenSSL. So make sure that your version of OpenSSL
support the FIPS object module before attempting to enable this
in Monit.
=head2 Monit HTTPD Authentication
Monit supports two types of authentication schema's for
connecting to the httpd server, (three, if you count SSL client
certificate validation). Both schema's can be used together or by
itself. You B<must> choose at least one.
=head4 Host and network allow list
The http server maintains an access-control list of hosts and
networks allowed to connect to the server. You can add as many
hosts as you want to, but only hosts with a valid domain name or
its IP address are allowed. Networks require a network IP and a
netmask to be accepted.
The http server will query a name server to check any hosts
connecting to the server. If a host (client) is trying to connect
to the server, but cannot be found in the access list or cannot
be resolved, the server will shutdown the connection to the
client promptly.
Control file example:
set httpd port 2812
allow localhost
allow my.other.work.machine.com
allow 10.1.1.1
allow 192.168.1.0/255.255.255.0
allow 10.0.0.0/8
Clients, not mentioned in the allow list, trying to connect to
the server are logged with their ip-address.
=head4 Basic Authentication
This authentication schema is HTTP specific and described in more
detail in RFC 2617.
In short; a server challenge a client (e.g. a Browser) to send
authentication information (username and password) and if
accepted, the server will allow the client access to the
requested document.
The biggest weakness with Basic Authentication is that the
username and password is sent in clear-text (i.e. base64 encoded)
over the network. It is therefor recommended that you do not use
this authentication method unless you run the Monit http server
with I<ssl> support. With ssl support it is completely safe to
use Basic Authentication since B<all> http data, including Basic
Authentication headers will be encrypted.
Monit will use Basic Authentication if an allow statement
contains a username and a password separated with a single ':'
character, like so: I<allow username:password>. The username and
password must be written in clear-text. Special characters
can be used but the password has to be quoted.
PAM is supported as well on platforms which provide PAM (such
as Linux, Mac OS X, FreeBSD, NetBSD). The syntax is:
I<allow @mygroup> which provides access to the user of group
called I<mygroup>. Monit uses PAM service called I<monit> for
PAM authentication, see PAM manual page for detailed instructions
how to set the PAM service and PAM authentication plugins.
Example Monit PAM for Mac OS X - /etc/pam.d/monit:
# monit: auth account password session
auth sufficient pam_securityserver.so
auth sufficient pam_unix.so
auth required pam_deny.so
account required pam_permit.so
And configuration part for monitrc which allows only group admins
authenticated using via PAM to access the http interface:
set httpd port 2812 allow @admin
Alternatively you can use files in "htpasswd" format (one
user:passwd entry per line), like so: I<allow
[cleartext|crypt|md5] /path [users]>. By default cleartext
passwords are read. In case the passwords are digested it is
necessary to specify the cryptographic method. If you do not want
all users in the password file to have access to Monit you can
specify only those users that should have access, in the allow
statement. Otherwise all users are added.
Example1:
set httpd port 2812
allow hauk:password
allow md5 /etc/httpd/htpasswd john paul ringo george
If you use this method together with a host list, then only
clients from the listed hosts will be allowed to connect to the
Monit http server and each client will be asked to provide a
username and a password.
Example2:
set httpd port 2812
allow localhost
allow 10.1.1.1
allow hauk:"password"
If you only want to use Basic Authentication, then just provide
allow entries with username and password or password files as in
example 1 above.
Finally it is possible to define some users as read-only. A
read-only user can read the Monit web pages but will I<not> get
access to push-buttons and cannot change a service from the web
interface.
set httpd port 2812
allow admin:password
allow hauk:password read-only
allow @admins
allow @users read-only
A user is set to read-only by using the I<read-only> keyword
B<after> username:password. In the above example the user I<hauk>
is defined as a read-only user, while the I<admin> user has all
access rights.
If you use Basic Authentication it is a good idea to set the
access permission for the control file (~/.monitrc) to only
readable and writable for the user running monit, because the
password is written in clear-text. (Use this command, /bin/chmod
600 ~/.monitrc). In fact, since Monit B<version 3.0>, Monit will
complain and exit if the control file is readable by others.
Clients trying to connect to the server but supply the wrong
username and/or password are logged with their ip-address.
If the Monit command line interface is being used, at least one
cleartext password is necessary. Otherwise, the Monit command
line interface will not be able to connect to the Monit daemon
server.
=head1 DEPENDENCIES
If specified in the control file, Monit can do dependency
checking before start, stop, monitoring or unmonitoring of
services. The dependency statement may be used within any service
entries in the Monit control file.
The syntax for the depend statement is simply:
=over 4
=item DEPENDS on service[, service [,...]]
=back
Where B<service> is a service entry name, for instance B<apache>
or B<datafs>.
You may add more than one service name of any type or use more
than one depend statement in an entry.
Services specified in a I<depend> statement will be checked
during stop/start/monitor/unmonitor operations. If a service is
stopped or unmonitored it will stop/unmonitor any services that
depends on itself. Likewise, if a service is started, it will
first stop any services that depends on itself and after it is
started, start all depending services again. If the service is to
be monitored (enable monitoring), all services which this service
depends on will be monitored before enabling monitoring of this
service.
Here is an example where we set up an apache service entry to
depend on the underlying apache binary. If the binary should
change an alert is sent and apache is not monitored anymore. The
rationale is security and that Monit should not execute a
possibly cracked apache binary.
(1) check process apache
(2) with pidfile "/usr/local/apache/logs/httpd.pid"
(3) ...
(4) depends on httpd
(5)
(6) check file httpd with path /usr/local/apache/bin/httpd
(7) if failed checksum then unmonitor
The first entry is the process entry for apache shown before
(abbreviated for clarity). The fourth line sets up a dependency
between this entry and the service entry named httpd in line 6. A
depend tree works as follows, if an action is conducted in a
lower branch it will propagate upward in the tree and for every
dependent entry execute the same action. In this case, if the
checksum should fail in line 7 then an unmonitor action is
executed and the apache binary is not checked anymore. But since
the apache process entry depends on the httpd entry this entry
will also execute the unmonitor action. In short, if the checksum
test for the httpd binary file should fail, both the check file
httpd entry and the check process apache entry is set in
un-monitoring mode.
A dependency tree is a general construct and can be used between
all types of service entries and span many levels and propagate
any supported action (except the exec action which will not
propagate upward in a dependency tree for obvious reasons).
Here is another different example. Consider the following common
server setup:
WEB-SERVER -> APPLICATION-SERVER -> DATABASE -> FILESYSTEM
(a) (b) (c) (d)
You can set dependencies so that the web-server depends on the
application server to run before the web-server starts and the
application server depends on the database server and the
database depends on the file-system to be mounted before it
starts. See also the example section below for examples using the
depend statement.
Here we describe how Monit will function with the above
dependencies:
=over 4
=item If no servers are running
Monit will start the servers in the following order: I<d>, I<c>,
I<b>, I<a>
=item If all servers are running
When you run 'Monit stop all' this is the stop order: I<a>, I<b>,
I<c>, I<d>. If you run 'Monit stop d' then I<a>, I<b> and I<c>
are also stopped because they depend on I<d> and finally I<d> is
stopped.
=item If I<a> does not run
When Monit runs it will start I<a>
=item If I<b> does not run
When Monit runs it will first stop I<a> then start I<b> and
finally start I<a> again.
=item If I<c> does not run
When Monit runs it will first stop I<a> and I<b> then start I<c>
and finally start I<b> then I<a>.
=item If I<d> does not run
When Monit runs it will first stop I<a>, I<b> and I<c> then start
I<d> and finally start I<c>, I<b> then I<a>.
=item If the control file contains a depend loop.
A depend loop is for example; a->b and b->a or a->b->c->a.
When Monit starts it will check for such loops and complain and
exit if a loop was found. It will also exit with a complaint if a
depend statement was used that does not point to a service in the
control file.
=back
=head1 THE RUN CONTROL FILE
The preferred way to set up Monit is to write a I<.monitrc> file
in your home directory. When there is a conflict between the
command-line arguments and the arguments in this file, the
command-line arguments take precedence. To protect the security
of your control file and passwords the control file must have
permissions I<no more than 0700> (u=xrw,g=,o=); Monit will
complain and exit otherwise.
=head2 Run Control Syntax
Comments begin with a '#' and extend through the end of the line.
Otherwise the file consists of a series of service entries or
global option statements in a free-format, token-oriented syntax.
There are three kinds of tokens: grammar , numbers (i.e.
decimal digit sequences) and strings. Strings can be either
quoted or unquoted. A quoted string is bounded by double quotes
and may contain whitespace (and quoted digits are treated as a
string). An unquoted string is any whitespace-delimited token,
containing characters and/or numbers.
On a semantic level, the control file consists of two types of
entries:
=over 4
=item 1. Global set-statements
A global set-statement starts with the keyword I<set> and the
item to configure.
=item 2. One or more service entry statements.
Each service entry consists of the keywords `check', followed by
the service type. Each entry requires a <unique> descriptive
name, which may be freely chosen. This name is used by monit
to refer to the service internally and in all interactions
with the user.
=back
Currently, eight types of check statements are supported:
=over 4
=item 1. CHECK PROCESS <unique name> <PIDFILE <path> | MATCHING <regex>>
<path> is the absolute path to the program's pidfile. If the
pidfile does not exist or does not contain the pid number of a
running process, Monit will call the entry's start method if
defined.
<regex> is alternative process specification using pattern matching
to process name (command line) from process table instead of pidfile.
The first match is used so this form of check is useful for unique
pattern matching - the pidfile should be used where possible as it
defines expected pid exactly (pattern matching won't be useful for
Apache in most cases for example).
The pattern can be obtained using I<monit procmatch ".*"> CLI command
which lists all processes visible to Monit or using the I<ps> utility.
The "procmatch" CLI command can be used to test your pattern as well.
If Monit runs in passive mode or the start methods is not defined,
Monit will just send alerts on errors.
=item 2. CHECK FILE <unique name> PATH <path>
<path> is the absolute path to the file. If the file does not
exist or disappeared, Monit will call the entry's start method if
defined, if <path> does not point to a regular file type (for
instance a directory), Monit will disable monitoring of this
entry. If Monit runs in passive mode or the start methods is not
defined, Monit will just send alerts on errors.
=item 3. CHECK FIFO <unique name> PATH <path>
<path> is the absolute path to the fifo. If the fifo does not
exist or disappeared, Monit will call the entry's start method if
defined, if <path> does not point to a fifo type (for
instance a directory), Monit will disable monitoring of this
entry. If Monit runs in passive mode or the start methods is not
defined, Monit will just send alerts on errors.
=item 4. CHECK FILESYSTEM <unique name> PATH <path>
<path> is the path to the filesystem block special device, mount point,
file or a directory which is part of a filesystem. It is
recommended to use a block special file directly (for example
/dev/hda1 on Linux or /dev/dsk/c0t0d0s1 on Solaris, etc.) If you
use a mount point (for example /data), be careful, because if the
filesystem is unmounted the test will still be true because the mount
point exist.
If the filesystem becomes unavailable, Monit will call the entry's
start method if defined. if <path> does not point to a filesystem,
Monit will disable monitoring of this entry. If Monit runs in
passive mode or the start methods is not defined, Monit will just
send alerts on errors.
=item 5. CHECK DIRECTORY <unique name> PATH <path>
<path> is the absolute path to the directory. If the directory
does not exist or disappeared, Monit will call the entry's start
method if defined, if <path> does not point to a directory, monit
will disable monitoring of this entry. If Monit runs in passive
mode or the start methods is not defined, Monit will just send
alerts on errors.
=item 6. CHECK HOST <unique name> ADDRESS <host address>
The host address can be specified as a hostname string or as an
ip-address string on a dotted decimal format. Such as,
tildeslash.com or "64.87.72.95".
=item 7. CHECK SYSTEM <unique name>
The system name is usually hostname, but any descriptive name can be
used. This test allows one to check general system resources such as
CPU usage (percent of time spent in user, system and wait), total
memory usage or load average.
=item 8. CHECK PROGRAM <unique name> PATH <executable file>
<path> is the absolute path to the executable program or script.
The I<status> test allows to check the program's exit status.
=back
You can use noise keywords like 'if', `and', `with(in)', `has',
`using', 'use', 'on(ly)', `usage' and `program(s)' anywhere in an
entry to make it resemble English. They're ignored, but can make
entries much easier to read at a glance. The punctuation
characters ';' ',' and '=' are also ignored. Keywords are case
insensitive.
Here are the legal global keywords:
Keyword Function
----------------------------------------------------------------
set daemon Set a background poll interval in seconds.
set init Set Monit to run from init. Monit will not
transform itself into a daemon process.
set logfile Name of a file to dump error- and status-
messages to. If syslog is specified as the
file, Monit will utilize the syslog daemon
to log messages. This can optionally be
followed by 'facility <facility>' where
facility is 'log_local0' - 'log_local7' or
'log_daemon'. If no facility is specified,
LOG_USER is used.
set mailserver The mailserver used for sending alert
notifications. If the mailserver is not
defined, Monit will try to use 'localhost'
as the smtp-server for sending mail. You
can add more mail servers, if Monit cannot
connect to the first server it will try the
next server and so on.
set mail-format Set a global mail format for all alert
messages emitted by monit.
set idfile Explicit set the location of the Monit id
file. E.g. set idfile /var/monit/id.
set pidfile Explicit set the location of the Monit lock
file. E.g. set pidfile /var/run/xyzmonit.pid.
set statefile Explicit set the location of the file Monit
will write state data to. If not set, the
default is $HOME/.monit.state.
set httpd port Activates Monit http server at the given
port number.
ssl enable Enables ssl support for the httpd server.
Requires the use of the pemfile statement.
ssl disable Disables ssl support for the httpd server.
It is equal to omitting any ssl statement.
pemfile Set the pemfile to be used with ssl.
clientpemfile Set the pemfile to be used when client
certificates should be checked by monit.
address If specified, the http server will only
accept connect requests to this addresses
This statement is an optional part of the
set httpd statement.
allow Specifies a host or IP address allowed to
connect to the http server. Can also specify
a username and password allowed to connect
to the server. More than one allow statement
are allowed. This statement is also an
optional part of the set httpd statement.
read-only Set the user defined in username:password
to read only. A read-only user cannot change
a service from the Monit web interface.
include include a file or files matching the globstring
Here are the legal service entry keywords:
Keyword Function
----------------------------------------------------------------
check Starts an entry and must be followed by the type
of monitored service {filesystem|directory|file|host
process|system|program} and a descriptive name for
the service.
pidfile Specify the process pidfile. Every
process must create a pidfile with its
current process id. This statement should only
be used in a process service entry.
path Must be followed by a path to the block
special file for filesystem, regular
file, directory or a process's pidfile.
group Specify a groupname for a service entry.
start The program used to start the specified
service. Full path is required. This
statement is optional, but recommended.
stop The program used to stop the specified
service. Full path is required. This
statement is optional, but recommended.
pid and ppid These keywords may be used as standalone
statements in a process service entry to
override the alert action for change of
process pid and ppid.
uid and gid These keywords are either 1) an optional part of
a start, stop or exec statement. They may be
used to specify a user id and a group id the
program (process) should switch to upon start.
This feature can only be used if the superuser
is running monit. 2) uid and gid may also be
used as standalone statements in a file service
entry to test a file's uid and gid attributes.
host The hostname or IP address to test the port
at. This keyword can only be used together
with a port statement or in the check host
statement.
port Specify a TCP/IP service port number which
a process is listening on. This statement
is also optional. If this statement is not
prefixed with a host-statement, localhost is
used as the hostname to test the port at.
type Specifies the socket type Monit should use when
testing a connection to a port. If the type
keyword is omitted, tcp is used. This keyword
must be followed by either tcp, udp or tcpssl.
tcp Specifies that Monit should use a TCP
socket type (stream) when testing a port.
tcpssl Specifies that Monit should use a TCP socket
type (stream) and the secure socket layer (ssl)
when testing a port connection.
udp Specifies that Monit should use a UDP socket
type (datagram) when testing a port.
certmd5 The md5 sum of a certificate a ssl forged
server has to deliver.
proto(col) This keyword specifies the type of service
found at the port. See CONNECTION TESTING
for list of supported protocols.
You're welcome to write new protocol test
modules. If no protocol is specified Monit will
use a default test which in most cases are good
enough.
request Specifies a server request and must come
after the protocol keyword mentioned above.
- for http it can contain an URL and an
optional query string.
- other protocols does not support this
statement yet
send/expect These keywords specify a generic protocol.
Both require a string whether to be sent or
to be matched against (as extended regex if
supported). Send/expect can not be used
together with the proto(col) statement.
unix(socket) Specifies a Unix socket file and used like
the port statement above to test a Unix
domain network socket connection.
URL Specify an URL string which Monit will use for
connection testing.
content Optional sub-statement for the URL statement.
Specifies that Monit should test the content
returned by the server against a regular
expression.
timeout x sec. Define a network port connection timeout. Must
be followed by a number in seconds and the
keyword, seconds.
timeout Define a service timeout. Must be followed by
two digits. The first digit is max number of
restarts for the service. The second digit
is the cycle interval to test restarts.
This statement is optional.
alert Specifies an email address for notification
if a service event occurs. Alert can also
be postfixed, to only send a message for
certain events. See the examples above. More
than one alert statement is allowed in an
entry. This statement is also optional.
noalert Specifies an email address which don't want
to receive alerts. This statement is also
optional.
restart, stop These keywords may be used as actions for
unmonitor, various test statements. The exec statement is
start and special in that it requires a following string
exec specifying the program to be execute. You may
also specify an UID and GID for the exec
statement. The program executed will then run
using the specified user id and group id.
mail-format Specifies a mail format for an alert message
This statement is an optional part of the
alert statement.
checksum Specify that Monit should compute and monitor a
file's md5/sha1 checksum. May only be used in a
check file entry.
expect Specifies a md5/sha1 checksum string Monit
should expect when testing the checksum. This
statement is an optional part of the checksum
statement.
timestamp Specifies an expected timestamp for a file
or directory. More than one timestamp statement
are allowed. May only be used in a check file or
check directory entry.
changed Part of a timestamp statement and used as an
operator to simply test for a timestamp change.
every Validate this entry only at every n poll cycle
or per cron specification. Useful in daemon mode
when the cycle is short and a service takes some
time to start or to suppress monitoring during
backup windows.
mode Must be followed either by the keyword active,
passive or manual. If active, Monit will restart
the service if it is not running (this is the
default behavior). If passive, Monit will not
(re)start the service if it is not running - it
will only monitor and send alerts (resource
related restart and stop options are ignored
in this mode also). If manual, Monit will enter
active mode only if a service was started under
monit's control otherwise the service isn't
monitored.
cpu Must be followed by a compare operator, a number
with "%" and an action. This statement is used
to check the cpu usage in percent of a process
with its children over a number of cycles. If
the compare expression matches then the
specified action is executed.
mem The equivalent to the cpu token for memory of a
process (w/o children!). This token must be
followed by a compare operator a number with
unit {B|KB|MB|GB|%|byte|kilobyte|megabyte|
gigabyte|percent} and an action.
swap Token for system swap usage monitoring. This token
must be followed by a compare operator a number with
unit {B|KB|MB|GB|%|byte|kilobyte|megabyte|gigabyte|percent}
and an action.
loadavg Must be followed by [1min,5min,15min] in (), a
compare operator, a number and an action. This
statement is used to check the system load
average over a number of cycles. If the compare
expression matches then the specified action is
executed.
children This is the number of child processes spawn by a
process. The syntax is the same as above.
totalmem The equivalent of mem, except totalmem is an
aggregation of memory, not only used by a
process but also by all its child
processes. The syntax is the same as above.
space Must be followed by a compare operator, a
number, unit {B|KB|MB|GB|%|byte|kilobyte|
megabyte|gigabyte|percent} and an action.
inode(s) Must be followed by a compare operator, integer
number, optionally by percent sign (if not, the
limit is absolute) and an action.
perm(ission) Must be followed by an octal number describing
the permissions.
size Must be followed by a compare operator, a
number, unit {B|KB|MB|GB|byte|kilobyte|
megabyte|gigabyte} and an action.
uptime Must be followed by a compare operator, a
number, unit {second(s)|minute(s)|hour(s)|day(s)}
and an action.
depends (on) Must be followed by the name of a service this
service depends on.
Here's the complete list of reserved B<keywords> used by monit:
I<if>, I<then>, I<else>, I<set>, I<daemon>, I<logfile>,
I<syslog>, I<address>, I<httpd>, I<ssl>, I<enable>, I<disable>,
I<pemfile>, I<allow>, I<read-only>, I<check>, I<init>, I<count>,
I<pidfile>, I<statefile>, I<group>, I<start>, I<stop>, I<uid>,
I<gid>, I<connection>, I<port(number)>, I<unix(socket)>, I<type>,
I<proto(col)>, I<tcp>, I<tcpssl>, I<udp>, I<alert>, I<noalert>,
I<mail-format>, I<restart>, I<timeout>, I<checksum>, I<resource>,
I<expect>, I<send>, I<mailserver>, I<every>, I<mode>, I<active>,
I<passive>, I<manual>, I<depends>, I<host>, I<default>, I<http>,
I<ftp>, I<smtp>, I<pop>, I<ntp3>, I<nntp>, I<imap>, I<clamav>,
I<ssh>, I<dwp>, I<ldap2>, I<ldap3>, I<tns>, I<request>, I<cpu>,
I<mem>, I<totalmem>, I<swap>, I<children>, I<loadavg>, I<timestamp>,
I<changed>, I<second(s)>, I<minute(s)>, I<hour(s)>, I<day(s)>,
I<space>, I<inode>, I<pid>, I<ppid>, I<perm(ission)>, I<icmp>,
I<process>, I<file>, I<directory>, I<filesystem>, I<size>, I<action>,
I<unmonitor>, I<rdate>, I<rsync>, I<data>, I<invalid>, I<exec>,
I<nonexist>, I<policy>, I<reminder>, I<instance>, I<eventqueue>,
I<basedir>, I<slot(s)>, I<system>, I<idfile>, I<gps>, I<radius>,
I<secret>, I<target>, I<maxforward>, I<hostheader>, I<register>,
I<credentials>, I<fips>, I<status>, I<uptime> and I<failed>
And here is a complete list of B<noise keywords> ignored by
monit:
I<is>, I<as>, I<are>, I<on(ly)>, I<with(in|out)>, I<and>, I<has>,
I<using>, I<use>, I<the>, I<sum>, I<program(s)>, I<than>, I<for>,
I<usage>, I<was>, I<but>, I<of>.
B<Note:> If the I<start> or I<stop> programs are shell scripts,
then the script must begin with C<#!> and the remainder of the
first line must specify an interpreter for the program. E.g.
C<#!/bin/sh>
It's possible to write scripts directly into the I<start> and
I<stop> entries by using a string of shell-commands. Like so:
start="/bin/bash -c 'echo $$ > pidfile; exec program'"
stop="/bin/bash -c 'kill -s SIGTERM `cat pidfile`'"
=head2 CONFIGURATION EXAMPLES
The simplest form is just the check statement. In this example we
check to see if the server is running and log a message if not:
check process resin with pidfile /usr/local/resin/srun.pid
Checking process without pidfile:
check process pager matching "/sbin/dynamic_pager -F /private/var/vm/swapfile"
To have Monit start the server if it's not running, add a start
statement:
check process resin with pidfile /usr/local/resin/srun.pid
start program = "/usr/local/resin/bin/srun.sh start"
stop program = "/usr/local/resin/bin/srun.sh stop"
Here's a more advanced example for monitoring an apache
web-server listening on the default port number for HTTP and
HTTPS. In this example Monit will restart apache if it's not
accepting connections at the port numbers. The method Monit use
for a process restart is to first execute the stop-program, wait
up to 30s for the process to stop and then execute the start-program
and wait up to 30s for it to start. The length of start or stop
timeout can be overridden using the 'timeout' option. If Monit was
unable to stop or start the service a failed alert message will
be sent if you have requested alert messages to be sent.
check process apache with pidfile /var/run/httpd.pid
start program = "/etc/init.d/httpd start" with timeout 60 seconds
stop program = "/etc/init.d/httpd stop"
if failed port 80 then restart
if failed port 443 with timeout 15 seconds then restart
This example demonstrate how you can run a program as a specified
user (uid) and with a specified group (gid). Many daemon programs
will do the uid and gid switch by them self, but for those
programs that does not (e.g. Java programs), monit's ability to
start a program as a certain user can be very useful. In this
example we start the Tomcat Java Servlet Engine as the standard
I<nobody> user and group. Please note that Monit will only switch
uid and gid for a program if the super-user is running monit,
otherwise Monit will simply ignore the request to change uid and
gid.
check process tomcat with pidfile /var/run/tomcat.pid
start program = "/etc/init.d/tomcat start"
as uid nobody and gid nobody
stop program = "/etc/init.d/tomcat stop"
# You can also use id numbers instead and write:
as uid 99 and with gid 99
if failed port 8080 then alert
In this example we use udp for connection testing to check if the
name-server is running and also use timeout and alert:
check process named with pidfile /var/run/named.pid
start program = "/etc/init.d/named start"
stop program = "/etc/init.d/named stop"
if failed port 53 use type udp protocol dns then restart
if 3 restarts within 5 cycles then timeout
The following example illustrates how to check if the service
'sophie' is answering connections on its Unix domain socket:
check process sophie with pidfile /var/run/sophie.pid
start program = "/etc/init.d/sophie start"
stop program = "/etc/init.d/sophie stop"
if failed unix /var/run/sophie then restart
In this example we check an apache web-server running on
localhost that answers for several IP-based virtual hosts or
vhosts, hence the host statement before port:
check process apache with pidfile /var/run/httpd.pid
start "/etc/init.d/httpd start"
stop "/etc/init.d/httpd stop"
if failed host www.sol.no port 80 then alert
if failed host shop.sol.no port 443 then alert
if failed host chat.sol.no port 80 then alert
if failed host www.tildeslash.com port 80 then alert
To make sure that Monit is communicating with a http server a
protocol test can be added:
check process apache with pidfile /var/run/httpd.pid
start "/etc/init.d/httpd start"
stop "/etc/init.d/httpd stop"
if failed host www.sol.no port 80
protocol HTTP
then alert
This example shows a different way to check a webserver using
the send/expect mechanism:
check process apache with pidfile /var/run/httpd.pid
start "/etc/init.d/httpd start"
stop "/etc/init.d/httpd stop"
if failed host www.sol.no port 80
send "GET / HTTP/1.0\r\nHost: www.sol.no\r\n\r\n"
expect "HTTP/[0-9\.]{3} 200 .*\r\n"
then alert
To make sure that Apache is logging successfully (i.e. no more
than 60 percent of child servers are logging), use its mod_status
page at www.sol.no/server-status with this special protocol test:
check process apache with pidfile /var/run/httpd.pid
start "/etc/init.d/httpd start"
stop "/etc/init.d/httpd stop"
if failed host www.sol.no port 80
protocol apache-status loglimit > 60% then restart
This configuration can be used to alert you if 25 percent or more
of Apache child processes are stuck performing DNS lookups:
check process apache with pidfile /var/run/httpd.pid
start "/etc/init.d/httpd start"
stop "/etc/init.d/httpd stop"
if failed host www.sol.no port 80
protocol apache-status dnslimit > 25% then alert
Here we use an icmp ping test to check if a remote host is up and
if not send an alert:
check host www.tildeslash.com with address www.tildeslash.com
if failed icmp type echo count 5 with timeout 15 seconds
then alert
In the following example we ask Monit to compute and verify the
checksum for the underlying apache binary used by the start and
stop programs. If the the checksum test should fail, monitoring
will be disabled to prevent possibly starting a compromised
binary:
check process apache with pidfile /var/run/httpd.pid
start program = "/etc/init.d/httpd start"
stop program = "/etc/init.d/httpd stop"
if failed host www.tildeslash.com port 80 then restart
depends on apache_bin
check file apache_bin with path /usr/local/apache/bin/httpd
if failed checksum then unmonitor
In this example we ask Monit to test the checksum for a document
on a remote server. If the checksum was changed we send an alert:
check host tildeslash with address www.tildeslash.com
if failed port 80 protocol http
and request "/monit/dist/monit-4.0.tar.gz"
with checksum f9d26b8393736b5dfad837bb13780786
then alert
Here are a couple of tests for some popular communication
servers, using the SIP protocol. First we test a FreeSWITCH
server and then an Asterisk server
check process freeswitch
with pidfile /usr/local/freeswitch/log/freeswitch.pid
start program = “/usr/local/freeswitch/bin/freeswitch -nc -hp”
stop program = “/usr/local/freeswitch/bin/freeswitch -stop”
if totalmem > 1000.0 MB for 5 cycles then alert
if totalmem > 1500.0 MB for 5 cycles then alert
if totalmem > 2000.0 MB for 5 cycles then restart
if cpu > 60% for 5 cycles then alert
if failed port 5060 type udp protocol SIP
target me@foo.bar and maxforward 10
then restart
if 5 restarts within 5 cycles then timeout
check process asterisk
with pidfile /var/run/asterisk/asterisk.pid
start program = “/usr/sbin/asterisk”
stop program = “/usr/sbin/asterisk -r -x ’shutdown now’”
if totalmem > 1000.0 MB for 5 cycles then alert
if totalmem > 1500.0 MB for 5 cycles then alert
if totalmem > 2000.0 MB for 5 cycles then restart
if cpu > 60% for 5 cycles then alert
if failed port 5060 type udp protocol SIP
and target me@foo.bar maxforward 10
then restart
if 5 restarts within 5 cycles then timeout
Some servers are slow starters, like for example Java based
Application Servers. So if we want to keep the poll-cycle low
(i.e. < 60 seconds) but allow some services to take its time to
start, the B<every> statement is handy:
check process dynamo with pidfile /etc/dynamo.pid every 2 cycles
start program = "/etc/init.d/dynamo start"
stop program = "/etc/init.d/dynamo stop"
if failed port 8840 then alert
Here is an example where we group together two database entries
so you can manage them together, e.g.; 'Monit -g database start
all'. The mode statement is also illustrated in the first entry
and have the effect that Monit will not try to (re)start this
service if it is not running:
check process sybase with pidfile /var/run/sybase.pid
start = "/etc/init.d/sybase start"
stop = "/etc/init.d/sybase stop"
mode passive
group database
check process oracle with pidfile /var/run/oracle.pid
start program = "/etc/init.d/oracle start"
stop program = "/etc/init.d/oracle stop"
mode active # Not necessary really, since it's the default
if failed port 9001 then restart
group database
Here is an example to show the usage of the resource checks. It
will send an alert when the CPU usage of the http daemon and its
child processes raises beyond 60% for over two cycles. Apache is
restarted if the CPU usage is over 80% for five cycles or the
memory usage over 100Mb for five cycles or if the machines load
average is more than 10 for 8 cycles:
check process apache with pidfile /var/run/httpd.pid
start program = "/etc/init.d/httpd start"
stop program = "/etc/init.d/httpd stop"
if cpu > 40% for 2 cycles then alert
if totalcpu > 60% for 2 cycles then alert
if totalcpu > 80% for 5 cycles then restart
if mem > 100 MB for 5 cycles then stop
if loadavg(5min) greater than 10.0 for 8 cycles then stop
This examples demonstrate the timestamp statement with exec and
how you may restart apache if its configuration file was
changed.
check file httpd.conf with path /etc/httpd/httpd.conf
if changed timestamp
then exec "/etc/init.d/httpd graceful"
In this example we demonstrate usage of the extended alert
statement and a file check dependency:
check process apache with pidfile /var/run/httpd.pid
start = "/etc/init.d/httpd start"
stop = "/etc/init.d/httpd stop"
alert admin@bar on {nonexist, timeout}
with mail-format {
from: bofh@$HOST
subject: apache $EVENT - $ACTION
message: This event occurred on $HOST at $DATE.
Your faithful employee,
monit
}
if failed host www.tildeslash.com port 80 then restart
if 3 restarts within 5 cycles then timeout
depend httpd_bin
group apache
check file httpd_bin with path /usr/local/apache/bin/httpd
alert security@bar on {checksum, timestamp,
permission, uid, gid}
with mail-format {subject: Alaaarrm! on $HOST}
if failed checksum
and expect 8f7f419955cefa0b33a2ba316cba3659
then unmonitor
if failed permission 755 then unmonitor
if failed uid root then unmonitor
if failed gid root then unmonitor
if changed timestamp then alert
group apache
In this example, we demonstrate usage of the depend statement. In
this case, we want to start oracle and apache. However, we've set
up apache to use oracle as a back end, and if oracle is
restarted, apache must be restarted as well.
check process apache with pidfile /var/run/httpd.pid
start = "/etc/init.d/httpd start"
stop = "/etc/init.d/httpd stop"
depends on oracle
check process oracle with pidfile /var/run/oracle.pid
start = "/etc/init.d/oracle start"
stop = "/etc/init.d/oracle stop"
if failed port 9001 then restart
Next, we have 2 services, oracle-import and oracle-export that
need to be restarted if oracle is restarted, but are independent
of each other.
check process oracle with pidfile /var/run/oracle.pid
start = "/etc/init.d/oracle start"
stop = "/etc/init.d/oracle stop"
if failed port 9001 then restart
check process oracle-import
with pidfile /var/run/oracle-import.pid
start = "/etc/init.d/oracle-import start"
stop = "/etc/init.d/oracle-import stop"
depends on oracle
check process oracle-export
with pidfile /var/run/oracle-export.pid
start = "/etc/init.d/oracle-export start"
stop = "/etc/init.d/oracle-export stop"
depends on oracle
Finally an example with all statements:
check process apache with pidfile /var/run/httpd.pid
start program = "/etc/init.d/httpd start"
stop program = "/etc/init.d/httpd stop"
if 3 restarts within 5 cycles then timeout
if failed host www.sol.no port 80 protocol http
and use the request "/login.cgi"
then alert
if failed host shop.sol.no port 443 type tcpssl
protocol http and with timeout 15 seconds
then restart
if cpu is greater than 60% for 2 cycles then alert
if cpu > 80% for 5 cycles then restart
if totalmem > 100 MB then stop
if children > 200 then alert
alert bofh@bar with mail-format {from: monit@foo.bar.no}
every 2 cycles
mode active
depends on weblogic
depends on httpd.pid
depends on httpd.conf
depends on httpd_bin
depends on datafs
group server
check file httpd.pid with path /usr/local/apache/logs/httpd.pid
group server
if timestamp > 7 days then restart
every 2 cycles
alert bofh@bar with mail-format {from: monit@foo.bar.no}
depends on datafs
check file httpd.conf with path /etc/httpd/httpd.conf
group server
if timestamp was changed
then exec "/usr/local/apache/bin/apachectl graceful"
every 2 cycles
alert bofh@bar with mail-format {from: monit@foo.bar.no}
depends on datafs
check file httpd_bin with path /usr/local/apache/bin/httpd
group server
if failed checksum and expect the sum
8f7f419955cefa0b33a2ba316cba3659 then unmonitor
if failed permission 755 then unmonitor
if failed uid root then unmonitor
if failed gid root then unmonitor
if changed size then alert
if changed timestamp then alert
every 2 cycles
alert bofh@bar with mail-format {from: monit@foo.bar.no}
alert foo@bar on { checksum, size, timestamp, uid, gid }
depends on datafs
check filesystem datafs with path /dev/sdb1
group server
start program = "/bin/mount /data"
stop program = "/bin/umount /data"
if failed permission 660 then unmonitor
if failed uid root then unmonitor
if failed gid disk then unmonitor
if space usage > 80 % then alert
if space usage > 94 % then stop
if inode usage > 80 % then alert
if inode usage > 94 % then stop
alert root@localhost
check host ftp.redhat.com with address ftp.redhat.com
if failed icmp type echo with timeout 15 seconds
then alert
if failed port 21 protocol ftp
then exec "/usr/X11R6/bin/xmessage -display
:0 ftp connection failed"
alert foo@bar.com
check host www.gnu.org with address www.gnu.org
if failed port 80 protocol http
and request "/pub/gnu/bash/bash-2.05b.tar.gz"
with checksum 8f7f419955cefa0b33a2ba316cba3659
then alert
alert rms@gnu.org with mail-format {
subject: The gnu server may be hacked again! }
Note: only the B<check statement> is mandatory, the other
statements are optional and the order of the optional statements
is not important.
=head1 FILES
F<~/.monitrc>
Default run control file
F</etc/monitrc>
If the control file is not found in the default
location and /etc contains a F<monitrc> file, this
file will be used instead.
F<./monitrc>
If the control file is not found in either of the
previous two locations, and the current working
directory contains a F<monitrc> file, this file is
used instead.
F<~/.monit.pid>
Lock file to help prevent concurrent runs (non-root
mode).
F</var/run/monit.pid>
Lock file to help prevent concurrent runs (root mode,
Linux systems).
F</etc/monit.pid>
Lock file to help prevent concurrent runs (root mode,
systems without /var/run).
F<~/.monit.state>
Monit saves its state to this file and utilizes
information found in this file to recover from
a crash. This is a binary file and its content is
only of interest to monit. You may set the location
of this file in the Monit control file or by using
the -s switch when Monit is started.
F<~/.monit.id>
Monit save its unique id to this file.
=head1 ENVIRONMENT
No environment variables are used by Monit. However, when Monit
execute a script or a program Monit will set several environment
variables which can be utilized by the executable. The following
and I<only> the following environment variables are available:
=over 4
=item MONIT_EVENT
The event that occurred on the service
=item MONIT_DESCRIPTION
A description of the error condition
=item MONIT_SERVICE
The name of the service (from monitrc) on which the event
occurred.
=item MONIT_DATE
The time and date (rfc 822 style) the event occurred
=item MONIT_HOST
The host the event occurred on
=back
The following environment variables are only available for
process service entries:
=over 4
=item MONIT_PROCESS_PID
The process pid. This may be 0 if the process was (re)started,
=item MONIT_PROCESS_MEMORY
Process memory. This may be 0 if the process was (re)started,
=item MONIT_PROCESS_CHILDREN
Process children. This may be 0 if the process was (re)started,
=item MONIT_PROCESS_CPU_PERCENT
Process cpu%. This may be 0 if the process was (re)started,
=back
In addition the following spartan PATH environment variable is
available:
=over 4
=item PATH=/bin:/usr/bin:/sbin:/usr/sbin
=back
Scripts or programs that depends on other environment variables
or on a more verbose PATH must provide means to set these
variables by them self.
=head1 SIGNALS
If a Monit daemon is running, SIGUSR1 wakes it up from its sleep
phase and forces a poll of all services. SIGTERM and SIGINT will
gracefully terminate a Monit daemon. The SIGTERM signal is sent
to a Monit daemon if Monit is started with the I<quit> action
argument.
Sending a SIGHUP signal to a running Monit daemon will force
the daemon to reinitialize itself, specifically it will reread
configuration, close and reopen log files.
Running Monit in foreground while a background Monit daemon is
running will wake up the daemon.
=head1 NOTES
This is a very silent program. Use the -v switch if you want to
see what Monit is doing, and tail -f the logfile. Optionally for
testing purposes; you can start Monit with the -Iv switch. Monit
will then print debug information to the console, to stop monit
in this mode, simply press CTRL^C (i.e. SIGINT) in the same
console.
The syntax (and parser) of the control file was inspired by Eric
S. Raymond et al. excellent fetchmail program. Some portions of
this man page also receive inspiration from the same authors.
=head1 COPYRIGHT
Copyright (C) 2001-2012 by Tildeslash Ltd. All Rights Reserved.
This product is distributed in the hope that it will be useful,
but WITHOUT any warranty; without even the implied warranty of
MERCHANTABILITY or FITNESS for a particular purpose.
=head1 SEE ALSO
GNU text utilities; md5sum(1); sha1sum(1); openssl(1); glob(7);
regex(7); I<http://www.mmonit.com/>
=cut