Megaphone Commons

To configure a new check in Icinga, you need 4 components:

• A plugin file.  This is a command-line executable (script
  or binary) that can be run independently of Icinga.  It should
  return an errorlevel of 0, 1, 2, or 3, corresponding to "OK",
  "Warning", "Critical", and "Unknown".  These reside in the plugin
  folder, which is /usr/lib/nagios/plugins.  These should always be
  testable on the command line.  E.g.:

  root@rh5:/usr/lib/nagios/plugins# /usr/lib/nagios/plugins/check_dns -H jmaconsulting.biz -a 72.249.190.114
  DNS OK: 0.018 seconds response time. jmaconsulting.biz returns 72.249.190.114|time=0.018268s;;;0.000000
  root@rh5:/usr/lib/nagios/plugins# /usr/lib/nagios/plugins/check_dns -H jmaconsulting.biz -a 72.249.190.222
  DNS CRITICAL - expected '72.249.190.222' but got '72.249.190.114'
  

• A CheckCommand object.  This maps variables defined in Icinga to
  the command-line arguments the plugin requires.  CheckCommands can
  be anywhere in /etc/icinga2/conf.d (localhost only)
  or /etc/icinga2/zones.d/global-templates (distributed to all
  satellites).  Please
  use icinga::/etc/icinga2/zones.d/global-templates/CheckCommands
  for CheckCommands.   Place Icinga ships with many CheckCommands
  which are in /usr/share/icinga2/include/command-plugins.conf.
   CheckCommands can also define default values for arguments.  For
  instance, the check_dns plugin has a CheckCommand object as
  follows:

Show exampleHide example

            command = [ PluginDir + "/check_dns" ]

            arguments = {
                    "-H" = {
                            value = "$dns_lookup$"
                            description = "The name or address you want to query."
                    }
                    "-s" = {
                            value = "$dns_server$"
                            description = "Optional DNS server you want to use for the lookup."
                    }
                    "-a" = {
                            value = "$dns_expected_answers$"
                            description = "Optional ip address or host you expect the DNS server to return. Host must end with a dot (.). This option can be repeated multiple times (Returns OK if any value match). If multiple addresses are returned at once, you have to match the whole string of addresses separated with commas (sorted alphabetically)."
                    }
                    "-a_old" = {
                            key = "-a"
                            value ="$dns_expected_answer$"
                    }
                    "-A" = {
                            set_if = "$dns_authoritative$"
                    }
                    "-w" = {
                            value = "$dns_wtime$"
                            description = "Return warning if elapsed time exceeds value."
                    }
                    "-c" = {
                            value = "$dns_ctime$"
                            description = "Return critical if elapsed time exceeds value."
                    }
                    "-t" = {
                            value = "$dns_timeout$"
                            description = "Seconds before connection times out. Defaults to 10."
                    }
            }

            vars.dns_lookup = "$host.name$"
            vars.dns_expected_answer = "$check_address$"
            vars.dns_timeout = 10
    }

• A Service object.  This defines which hosts have this check
  applied, and can optionally define variables.  Services can be
  anywhere in /etc/icinga2/conf.d but should be in
  the services subfolder. The civicrm check is a simple one - only
  one CiviCRM check can be defined per host, and is only added if the
  three relevant variables are defined.  It looks like this:

  apply Service "civicrm" {
    import "generic-service"
  
    check_command = "civicrm"
  
    assign where host.vars.cms && host.vars.crm_site_key && host.vars.crm_api_key
  }
  

  The DNS check iterates over an array of one or more domains.  It
  doesn't need an assign where statement as a consequence (if the
  array is empty, no checks are added) but the syntax for iterating is
  different:

  apply Service for (domain => config in host.vars.domains) {
    import "generic-service"
  
    check_command = "dns"
  
    vars += config
  }
  

• A Host object.  Each server has a Host object - to run a service
  against 10 hosts, you would define 10 host objects.  Hosts contain
  all the host-specific variables.  Hosts can be anywhere
  in /etc/icinga2/conf.d but should be in the hosts subfolder.