Install Monit on Ubuntu

Monit can be used to monitor services, restart them if required. To install monit, run

apt -y install monit

To start monit, run

systemctl start monit

Monitor Apache

vi /etc/monit/conf-available/apache2-custom

Add

check process apache with pidfile /var/run/apache2/apache2.pid
    group www-data
    start program = "/etc/init.d/apache2 start"
    stop program  = "/etc/init.d/apache2 stop"
    if failed host localhost port 80 protocol http then restart
    if 5 restarts within 5 cycles then timeout

Activate the rule with

ln -s /etc/monit/conf-available/apache2-custom /etc/monit/conf-enabled/apache2-custom

Restart monit with

systemctl restart monit

Testing If Monit works

Open 2 terminals. On one, tail the monit logs with

tail -f /var/log/monit.log

On other terminal, stop Apache

service apache2 stop

Within 2 minutes, monit will restart apache web server.

monit