Restarting a service through monit with a restart.txt file

Nowadays we tend to automate a lot of things. Yet in some cases monit handles the daemons and their stop / start events.

As a result, often we require to enter a password to pass the sudo. I don't really like that, it stops me from automating or just firing the deploy from somewhere.

Nginx and other services have been supporting a neat way to restart processes : a simple file existence check. I like that.

And well Monit can actually do something similar.

With old monit you need 2 files : the monitrc script and a restart script :

# monitrc file
check file restart_resque
  with path /tmp/restart_resque.txt
  start program = "/usr/local/bin/resque_restart.sh"
  if timestamp > 1 minute then start
check file stop_resque
  with path /tmp/stop_resque.txt
  start program = "/usr/local/bin/resque_stop.sh"
  if timestamp > 1 minute then start

# script
#!/bin/bash
if [[ -f /tmp/restart_resque.txt ]]; then
  monit restart resque
  monit restart resque_scheduler
  rm /tmp/restart_resque.txt
fi

Newer versions let you do that in a single file :

check file restart_resque path /tmp/restart_resque.txt
  if not exist then exec "/bin/bash -c 'echo dne > /dev/null'" else if succeeded then exec "/bin/bash -c 'monit restart resque && monit restart resque_scheduler && rm /tmp/restart_resque.txt'"
check file stop_resque path /tmp/stop_resque.txt
  if not exist then exec "/bin/bash -c 'echo dne > /dev/null'" else if succeeded then exec "/bin/bash -c 'monit stop resque && monit stop resque_scheduler && rm /tmp/stop_resque.txt'"

If you are using capistrano you'll need to add something like the following :

run "touch /tmp/restart_resque.txt"

And voila. No more passwords.

Note : that's one way to do it, quite happy to hear other people ideas and tricks on the topic.