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Monit Configuration

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Robin Miller edited this page Sep 19, 2022 · 5 revisions

Here is a Monit config file guideline template. This is heavily dependent on your situation, so you're on your own to figure the details out.

  1. Replace the references to my-app with your app name. Use only alphanumerics, dash, and underscore.
  2. The pidfile must perfectly match the path defined in your rake task, or else you will get a Monit status of Execution failed | Does not exist
  3. You may want to change the uid and/or gid to a more general user/group like www-data if you are not using the recommended one-user-per-application style.
  4. Debian-family distributions (Ubuntu, PopOS, Mint, Debian, etc), keep Monit application config files in /etc/monit/conf-available/ with a symlink to it in /etc/monit/conf-enabled/.
  5. This is using bash --login to cause chruby to be loaded. If you do not use chruby, you may be able to simplify this step, but will need to provide absolute paths to everything.
  6. You can alternatively replace the start/stop commands with a path to custom-written shell script. This may be necessary/better if you need to set environment variables.

/etc/monit/conf-available/procrastinator-my-app.conf

# =======================================
#          Monit Config File
# =======================================
#
# See: https://mmonit.com/monit/documentation/monit.html
##

# Watches the process ID file and controls the process with that ID.
check process procrastinator-my-app
   with pidfile /tmp/procrastinator-my-app.pid
   # Start and stop use --login to load normal path, chruby, etc.
   start = "/bin/bash --login -c 'cd /var/www/my-app && bundle exec rake procrastinator:start'"
      with uid 'my-app'
      with gid 'my-app'
   stop  = "/bin/bash --login -c 'cd /var/www/my-app && bundle exec rake procrastinator:stop'"
   # These are Monit groupings, not posix user groups.
   group procrastinator
   group my-app

Troubleshooting

  • Make sure the pid file matches
  • Make sure the uid that runs the daemon has permissions to access all the code, bundle, and bundle config used in the task.
    • This can show up as bundler load errors where it cannot find a required gem but it is installed.
    • Possibly helpful bash command: find /var/www/my-app/* -not -user my-app
  • Check the /var/log/monit.log file for errrors.
  • Check the procrastinator.log file for errors (usually in your application directory ./log/)
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