Monit utility for monitoring services on Unix 

Problem - Don't know when your system is going to failed If it failed - You need to get it up and running ASAP 

Monit: What & Why - Automatically monitor your system - It is lightweight - Easy to install - Very stable - No require another separate management server - Has a great configuration syntax 

What to monitor - Disk space - Memory usage - CPU consumption - Process - Host - Port - File / Directory 

Installation $> sudo apt-get install monit 

/etc/monit/monitrc set daemon 30 set logfile /var/log/monit.log set mailserver localhost set alert [email protected] set httpd port 2812 include /etc/monit/conf.d/* 

Check system check system localhost.localdomain if loadavg (1min) > 8 then alert if loadavg (5min) > 5 then alert if memory usage > 75% then alert if swap usage > 25% 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 check process apache with pidfile /var/run/apache2.pid group www start "/etc/init.d/apache2 start" stop "/etc/init.d/apache2 stop" if cpu > 60% for 2 cycles then alert if cpu > 80% for 25 cycles then restart if totalmem > 2100.0 MB for 5 cycles then restart if loadavg (5min) > 10 for 8 cycles then stop if failed port 80 then restart if 5 restarts within 5 cycles then timeout 

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

Check host, ping & port check host my_example with address example.com group network if failed icmp type echo with timeout 15 seconds then alert if failed port 5060 type udp protocol sip then alert 

Matching process name check process verboice with matching "ruby lib/services/broker.rb" group app start "/sbin/start verboice" stop "/sbin/stop verboice" if cpu > 60% for 2 cycles then alert if cpu > 80% for 15 cycles then restart if totalmem > 1800.0 MB for 5 cycles then restart if loadavg (5min) > 8 for 8 cycles then restart if 5 restarts within 5 cycles then timeout 

Check file & directory check file access_log with path /var/log/access_log if size > 100 Mb then alert check directory sbin with path /sbin if changed timestamp then alert 

Monit command-line $> monit summary $> monit status $> monit reload $> monit start [all | name] $> monit stop [all | name] 

More settings and examples http://mmonit.com/monit/documentation/monit.html