installing monit

Installation

Monit is easiest to install through apt-get:

$ sudo apt-get install monit

Once monit downloads, you can add programs and processes to the configuration file:

$ sudo nano /etc/monit/monitrc

Monit can be started up with a command that then keeps it running in the background

$ monit

Typing monit status displays monit’s details:

The Monit daemon 5.3.2 uptime: 1h 25m

System 'myhost.mydomain.tld'
  status                            Running
  monitoring status                 Monitored
  load average                      [0.03] [0.14] [0.20]
  cpu                               3.5%us 5.9%sy 0.0%wa
  memory usage                      26100 kB [10.4%]
  swap usage                        0 kB [0.0%]
  data collected                    Thu, 30 Aug 2012 18:35:00

Configure Monit

Monit is very easy to use nearly out of the box. By default, it is set up to check that services are running every 2 minutes and stores its log file in “/var/log/monit.log”.

These settings can be altered at the beginning of the configuration file in the set daemon and set logfile lines respectively.

Web Service

Monit comes with it’s own web server running on port 2812. To configure the web interface, find and uncomment the section that begins with set httpd port 2812. Once the section is uncommented, write in your server’s IP or domain name as the address, allow anyone to connect, and then create a monit user and password

    set httpd port 2812
    use address 12.34.56.789  # only accept connection from localhost
    allow 0.0.0.0/0.0.0.0     # allow localhost to connect to the server and
    allow admin:monit         # require user 'admin' with password 'monit'

Once this is configured, monit should reload and reread the configuration file, and the web interface will be available:

$ monit reload

When you are done, try

http://12.34.56.789:2812 You will see a dialog box appear in the browser.

General Monit Scripts

Sidekiq

  # /etc/monit/conf-available/sidekiq
  check process sidekiq_thepact_staging0 with pidfile "/home/deployer/www/staging/shared/tmp/pids/sidekiq.pid"  
  start program = "/bin/su - deployer -c 'cd /home/deployer/www/staging/current && /usr/local/rvm/bin/rvm default do bundle exec sidekiq --config /home/deployer/www/staging/current/config/sidekiq.yml --index 0 -e staging -d'" with timeout 30 seconds  
  stop program  = "/bin/su - deployer -c 'cd /home/deployer/www/staging/current && /usr/local/rvm/bin/rvm default do bundle exec sidekiqctl stop /home/deployer/www/staging/shared/tmp/pids/sidekiq.pid'" with timeout 110 seconds  group thepact-sidekiq-0

PostGreSQL

 # /etc/monit/conf-available/pg
 check process postgres with pidfile /var/run/postgresql/9.5-main.pid
 group database
 start program = "/etc/init.d/postgresql start"
 stop program  = "/etc/init.d/postgresql stop"
 if failed unixsocket /var/run/postgresql/.s.PGSQL.5432 protocol pgsql
 then restart

Puma

 # /etc/monit/conf-available/puma
 check process puma with pidfile /var/www/myapp/production/shared/tmp/pids/puma.pid
 group www

 start program   = "/bin/su - john -c '~/.rvm/bin/rvm default do bundle exec puma -C /var/www/myapp/production/shared/puma.rb --daemon'"
 stop program    = "/bin/su - john -c 'pumactl stop -P /var/www/myapp/production/shared/tmp/pids/puma.pid'"
 restart program = "/bin/su - john -c 'pumactl restart -P /var/www/myapp/production/shared/tmp/pids/puma.pid'"

 # /etc/monit/conf-available/puma
 check process puma with pidfile /var/www/myapp/production/shared/tmp/pids/puma.pid
 group www
 start program   = "/bin/su - john -c '~/.rvm/bin/rvm default do bundle exec puma -C /var/www/myapp/production/shared/puma.rb --daemon'"
 stop program    = "/bin/su - john -c '~/.rvm/bin/rvm default do bundle exec pumactl -S /var/www/myapp/production/shared/tmp/pids/puma.state stop'"
 restart program = "/bin/su - john -c '~/.rvm/bin/rvm default do bundle exec pumactl -S /var/www/myapp/production/shared/tmp/pids/puma.state restart'"

Using the scripts

By default Monit does not load conf-scripts in conf-available. You have to copy the scripts to conf-enabled to have them executed by Monit. So, we are going to link those files that folder instead of copying/duplicating them. Its a good practice.

$ sudo ln /etc/monit/conf-available/puma /etc/monit/conf-enabled/puma

This will link the file there, same file will act as if it is there too.

Sources

digitalocean.com/community/tutorials/how-to..

Shiva's Blog