DevOps Classroom Series – 24/June/2021

Configuring Nagios object definitions

• Refer Here for the default Nagios configuration

Understanding how checks work

• Nagios requires all plugins to follow a specific, easy to follow behaviour
• Nagios relies on exit codes of the Nagios plugins

• Standard output from command is not parsed by Nagios and is usually formatted in the following way

PLUGIN STATUS - status description

• Nagios plugins use options for their configuration

  • -h, –help: This provides help
  • -V, –version: This prints the version
  • -v , –verbose: This prints the detailed information on what plugin is doing
  • -t , –timeout
  • -w, –warning
  • -c, –critical
  • -H, –hostname
  • -4, –use-ipv4
  • -6, –use-ipv6

• All the network related plugins have the following standard option

  • -p, –port
  • -w, –warning
  • -c, –critical
  • -s, –send: This provides the string that will be sent to server
  • -e, –expect: This provides the string that should be sent back from server
  • -q, –quit: This provides the string to be sent to close the connection
  • -S, –ssl
  • -D, –certificate

Testing the connection to remote host

• For this we have check_ping plugin Refer Here for official documentation
• Creating the command for the host-alive

define command {
    command_name   check-host-alive
    command_line   $USER1$/check_ping -H $HOSTADDRESS$ -w 2000,50% -c 5000,60% -p 5
}

Testing the connectivity using TCP and UDP

• Refer Here for the official documentation

Testing the websites

• Refer Here for the official documentation of check_http plugin

Testing the databases

• MySQL

  • check_mysql Refer Here
  • check_mysql_query Refer Here

• PostgreSQL

  • check_pgsql Refer Here

• Oracle: Refer Here

• For installing plugins Refer Here

• Now we have a basic idea on how to use plugins to fetch the basic connectivity

• Refer Here for sample commands written

Area of concern

• If we need to alert/notify the user on some details such as
  • free disk space
  • process
  • CPU stress