Monit (http://mmonit.com/monit/) script example

monit-example.txt

set daemon 20
set logfile syslog facility log_daemon
set mailserver smtp.gmail.com port 587
  username "ERROR-EMAIL-ADDRESS" password "PASSWORD"
  using tlsv1
  with timeout 30 seconds

set alert ERROR-EMAIL-ADDRESS

set httpd port 2812 and
  use address localhost
  allow localhost
  allow admin:monit
check system localhost
  if loadavg (1min) > 4 then alert
  if loadavg (5min) > 2 then alert
  if memory usage > 90% then alert
  if cpu usage (user) > 70% then alert
  if cpu usage (system) > 30% then alert
  if cpu usage (wait) > 20% then alert

check process nginx
  with pidfile /var/run/nginx.pid
  group www
  start program = "/etc/init.d/nginx start"
  stop program = "/etc/init.d/nginx stop"
  if children > 250 then restart
  if loadavg(5min) greater than 10 for 8 cycles then stop
  if 3 restarts within 5 cycles then timeout

check process mysql
  with pidfile /var/run/mysqld/mysqld.pid
  group database
  start program = "/etc/init.d/mysql start"
  stop program = "/etc/init.d/mysql stop"
  if failed host localhost port 3306 protocol mysql then restart
  if 5 restarts within 5 cycles then timeout

check process redis
  with pidfile /var/run/redis/redis-server.pid
  start program = "/etc/init.d/redis-server start"
  stop program = "/etc/init.d/redis-server stop"
  if failed host 127.0.0.1 port 6379 then restart
  if 5 restarts within 5 cycles then timeout
  group redis_workers

check process sidekiq
  with pidfile /var/www/project-name/current/tmp/pids/sidekiq.pid
  start program = "/bin/sh -c 'cd /var/www/project-name/current; PATH=/usr/local/bin:$PATH RAILS_ENV=production bundle exec sidekiq -C config/sidekiq.yml -P tmp/pids/sidekiq.pid" as uid deploy
  stop program = "/bin/sh -c 'cd /var/www/project-name/current && kill -s INT `cat tmp/pids/sidekiq.pid`'"
  if totalmem is greater than 200 MB for 10 cycles then restart  # eating up memory?
  group sidekiq_workers