Monit

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configuration examples

Setup Notes

You’ll need to ensure that the standard mailutils are installed on the server.

apt-get install postfix mailutils

Afterwards, modify the /etc/monit/monitrc file by uncommenting the following lines to enable emailed notifications

set mailserver localhost  #Use localhost for email delivery.

set mail-format {
      from: monit@$HOST
   subject: monit alert --  $EVENT $SERVICE
   message: $EVENT Service $SERVICE
                 Date:        $DATE
                 Action:      $ACTION
                 Host:        $HOST
                 Description: $DESCRIPTION
}

set alert derekz@example.org #Alert recipient

If you want to store notifications for dispatch, you’ll need to enable the notifications queue.

set eventqueue
	basedir /var/lib/monit/events # notifications store
	slots 100                     # limit the queue size

I don’t need to be informed when the instance state has changed or reloaded, so I silence those alerts by uncommenting this instance filter

## Do not alert when Monit starts, stops or performs a user initiated action.
 set alert derekz@example.org not on {instance}

Make sure to comment out any include file directories at the end of /etc/monit/monitrc. If a path is in the configuration file, but the file does not exist, monit will fail to start.

Commands

Monit Daemon

monit
monit reload
monit status
monit quit

Test Configuration

monit -t

Controlling Monitors

monit unmonitor all
monit monitor all

Alerts

Alert if new MARC files are added or removed from a directory

check directory marcfiles with path /home/admin/marc/
      if changed timestamp then alert

Alert if registered users file has not been updated in the past 24 hours

check directory registeredusers with path /home/admin/users
      if timestamp > 24 hour then alert

Call home every 500 cycles

check file testalert with path /.nonexistent
    alert derek@example.com with reminder on 500 cycles

Alert on low disk space

check filesystem rootfs with path /
    if space usage > 90% then alert

Monitor System Load

check system example.com
    if loadavg (1min) > 4 then alert
    if loadavg (5min) > 2 then alert
    if memory usage > 75% then alert
    if swap usage > 25% then alert
    if cpu usage (user) > 70% for 2 cycles then alert
    if cpu usage (system) > 30% for 2 cycles then alert
    if cpu usage (wait) > 20% for 2 cycles then alert

Double check the automated Let’s Encrypt SSL renewal process

check host mmonit.com with address mmonit.com
      if failed
         port 443
         with protocol https
         and certificate valid > 30 days
         use ssl options {verify: enable}
      then alert

Restart EZproxy, if service halts

check process ezproxy with pidfile /var/run/ezproxy.pid
      restart program  = "/usr/local/ezproxy/ezproxy restart"
      if failed port 80 protocol http for 2 cycles then restart

Alert on Apache Timeouts

check file apache-error with path /var/log/apache2/error.log
    if match "^timed out" then alert

Process patrons when a new file is uploaded

check directory patrons with path /home/admin/patrons/
      if changed timestamp then exec "/home/admin/scripts/process-patrons.py"