Use Monit to Monitor + Restart MySQL Service Automatically

Monit can be used to monitor your services on your VPS or dedicated server. You can use Monit to make sure MySQL (MariaDB, Percona etc) is always running in case it crashes because of bots brute forcing or it runs out of resources.

Monit will check the MySQL process by looking at the unix socket it is listening on. If the socket cannot be detected Monit will restart the MySQL service. This way you ensure your web site, perhaps running WordPress, is always running essential processes. Cloudways uses this monitoring technique with Monit on all of its managed VPS.

If you need to install Monit on Ubuntu or Debian then follow this guide.

Use Monit to Monitor + Restart MySQL Service Automatically

Monit needs some information to check to see if MySQL is healthy.

We will use the socket MariaDB or MySQL is using and its pid file.

Find MySQL Unix or TCP Socket

MySQL can listen on both unix sockets and TCP sockets. To find out use this command

grep "socket" /etc/mysql/my.cnf

If you see this output then MySQL is using unix sockets

listen = /var/run/mysqld/mysqld.sock

Find MySQL pid file

Monit needs the pid file as well

sudo find /run -iname mysql*.pid

You should see some output like this

/run/mysqld/mysqld.pid

Now we have the information necessary to configure Monit for MySQL monitoring.

Configure Monit to Monitor MySQL, MariaDB, Percona

Create a Monit MySQL configuration, you may use the conf-enabled folder instead of conf.d, check your /etc/monit/monitrc file to verify.

sudo nano /etc/monit/conf.d/mysql

This Monit MySQL configuration is for unix sockets.

It checks for the mysqld.pid file and if it doesn't exist Monit will try to restart it.

Monit is also going to check that the MySQL unix socket exists: /var/run/mysqld/mysqld.sock

check process mysql with pidfile /run/mysqld/mysqld.pid
    start program = "/usr/sbin/service mysql start" with timeout 60 seconds
    stop program  = "/usr/sbin/service mysql stop"
    if failed unixsocket /var/run/mysqld/mysqld.sock then restart

Check the Monit configuration has valid syntax

sudo monit -t

You should see this message indicating the Monit syntax is OK.

Control file syntax OK

Then reload Monit to activate the configuration

sudo service monit reload

You can check your MySQL Monit status on port 2812 or whichever port you have specified Monit should run on.

If you want email alerts from Monit via Mailgun alerts follow this guide. For Monit emails via Sendgrid follow this guide.

Now your MySQL service will automatically restart if it ever fails.