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Configuring Icinga 2: First Steps

This chapter prodides an introduction to the configuration files which are automatically created when installing the Icinga 2 packages.

If you're interested in a detailed explanation of each language feature used in those configuration files you can find more information in the Language Reference chapter.

icinga2.conf

An example configuration file is installed for you in /etc/icinga2/icinga2.conf.

Here's a brief description of the example configuration:

/**
 * Icinga 2 configuration file
 * - this is where you define settings for the Icinga application including
 * which hosts/services to check.
 *
 * For an overview of all available configuration options please refer
 * to the documentation that is distributed as part of Icinga 2.
 */

Icinga 2 supports C/C++-style comments.

/**
 * The constants.conf defines global constants.
 */
include "constants.conf"

The include directive can be used to include other files.

/**
 * The zones.conf defines zones for a cluster setup.
 * Not required for single instance setups.
 */
 include "zones.conf"

/**
 * The Icinga Template Library (ITL) provides a number of useful templates
 * and command definitions.
 * Common monitoring plugin command definitions are included separately.
 */
include <itl>
include <plugins>

/**
 * The features-available directory contains a number of configuration
 * files for features which can be enabled and disabled using the
 * icinga2 feature enable / icinga2 feature disable CLI commands.
 * These commands work by creating and removing symbolic links in
 * the features-enabled directory.
 */
include "features-enabled/*.conf"

This include directive takes care of including the configuration files for all the features which have been enabled with icinga2 feature enable. See Enabling/Disabling Features for more details.

/**
 * The repository.d directory contains all configuration objects
 * managed by the 'icinga2 repository' CLI commands.
 */
include_recursive "repository.d"

This include_recursive directive is used for discovery of services on remote clients and their generated configuration described in this chapter.

/**
 * Although in theory you could define all your objects in this file
 * the preferred way is to create separate directories and files in the conf.d
 * directory. Each of these files must have the file extension ".conf".
 */
include_recursive "conf.d"

You can put your own configuration files in the conf.d directory. This directive makes sure that all of your own configuration files are included.

constants.conf

The constants.conf configuration file can be used to define global constants.

By default, you need to make sure to set these constants:

The PluginDir constant must be set to the path where the Monitoring Project plugins are installed. This constant is used by a number of built-in check command definitions.
The NodeName constant defines your local node name. Should be set to FQDN which is the default if not set. This constant is required for local host configuration, monitoring remote clients and cluster setup.

Example:

/* The directory which contains the plugins from the Monitoring Plugins project. */
const PluginDir = "/usr/lib64/nagios/plugins"


/* The directory which contains the Manubulon plugins.
 * Check the documentation, chapter "SNMP Manubulon Plugin Check Commands", for details.
 */
const ManubulonPluginDir = "/usr/lib64/nagios/plugins"

/* Our local instance name. By default this is the server's hostname as returned by `hostname --fqdn`.
 * This should be the common name from the API certificate.
 */
//const NodeName = "localhost"

/* Our local zone name. */
const ZoneName = NodeName

/* Secret key for remote node tickets */
const TicketSalt = ""

The ZoneName and TicketSalt constants are required for remote client and distributed setups only.

The conf.d Directory

This directory contains example configuration which should help you get started with monitoring the local host and its services. It is included in the icinga2.conf configuration file by default.

It can be used as reference example for your own configuration strategy. Just keep in mind to include the main directories in the icinga2.conf file.

You are certainly not bound to it. Remove it, if you prefer your own way of deploying Icinga 2 configuration.

Further details on configuration best practice and how to build your own strategy is described in this chapter.

Available configuration files which are installed by default:

hosts.conf

The hosts.conf file contains an example host based on your NodeName setting in constants.conf. You can use global constants for your object names instead of string values.

The import keyword is used to import the generic-host template which takes care of setting up the host check command to hostalive. If you require a different check command, you can override it in the object definition.

The vars attribute can be used to define custom attributes which are available for check and notification commands. Most of the Plugin Check Commands in the Icinga Template Library require an address attribute.

The custom attribute os is evaluated by the linux-servers group in groups.conf making the local host a member.

The example host will show you how to

define http vhost attributes for the http service apply rule defined in services.conf.
define disks (all, specific /) and their attributes for the disk service apply rule defined in services.conf.
define notification types (mail) and set the groups attribute. This will be used by notification apply rules in notifications.conf.

If you've installed Icinga Web 2 you can uncomment the http vhost attributes and relaod Icinga 2. The apply rules in services.conf will automatically generate a new service checking the /icingaweb2 URI using the http check.

/*
 * Host definitions with object attributes
 * used for apply rules for Service, Notification,
 * Dependency and ScheduledDowntime objects.
 *
 * Tip: Use `icinga2 object list --type Host` to
 * list all host objects after running
 * configuration validation (`icinga2 daemon -C`).
 */

/*
 * This is an example host based on your
 * local host's FQDN. Specify the NodeName
 * constant in `constants.conf` or use your
 * own description, e.g. "db-host-1".
 */

object Host NodeName {
  /* Import the default host template defined in `templates.conf`. */
  import "generic-host"

  /* Specify the address attributes for checks e.g. `ssh` or `http`. */
  address = "127.0.0.1"
  address6 = "::1"

  /* Set custom attribute `os` for hostgroup assignment in `groups.conf`. */
  vars.os = "Linux"

  /* Define http vhost attributes for service apply rules in `services.conf`. */
  vars.http_vhosts["http"] = {
    http_uri = "/"
  }
  /* Uncomment if you've sucessfully installed Icinga Web 2. */
  //vars.http_vhosts["Icinga Web 2"] = {
  //  http_uri = "/icingaweb2"
  //}

  /* Define disks and attributes for service apply rules in `services.conf`. */
  vars.disks["disk"] = {
    /* No parameters. */
  }
  vars.disks["disk /"] = {
    disk_partitions = "/"
  }

  /* Define notification mail attributes for notification apply rules in `notifications.conf`. */
  vars.notification["mail"] = {
    /* The UserGroup `icingaadmins` is defined in `users.conf`. */
    groups = [ "icingaadmins" ]
  }
}

This is only the host object definition. Now we'll need to make sure that this host and your additional hosts are getting services applied.

Tip

If you don't understand all the attributes and how to use apply rules don't worry - the monitoring basics chapter will explain that in detail.

services.conf

These service apply rules will show you how to monitor the local host, but also allow you to re-use or modify them for your own requirements.

You should define all your service apply rules in services.conf or any other central location keeping them organized.

By default, the local host will be monitored by the following services

Service(s)	Applied on host(s)
`load`, `procs`, `swap`, `users`, `icinga`	The `NodeName` host only
`ping4`, `ping6`	All hosts with `address` resp. `address6` attribute
`ssh`	All hosts with `address` and `vars.os` set to `Linux`
`http`, optional: `Icinga Web 2`	All hosts with custom attribute `http_vhosts` defined as dictionary
`disk`, `disk /`	All hosts with custom attribute `disks` defined as dictionary

The Debian packages also include an additional apt service check applied to the local host.

The command object icinga for the embedded health check is provided by the Icinga Template Library (ITL) while http_ip, ssh, load, processes, users and disk are all provided by the Plugin Check Commands which we enabled earlier by including the itl and plugins configuration file.

Example load service apply rule:

apply Service "load" {
  import "generic-service"

  check_command = "load"

  /* Used by the ScheduledDowntime apply rule in `downtimes.conf`. */
  vars.backup_downtime = "02:00-03:00"

  assign where host.name == NodeName
}

The apply keyword can be used to create new objects which are associated with another group of objects. You can import existing templates, define (custom) attributes.

The custom attribe backup_downtime is defined to a specific timerange string. This variable value will be used for applying a ScheduledDowntime object to these services in downtimes.conf.

In this example the assign where condition is a boolean expression which is evaluated for all objects of type Host and a new service with name "load" is created for each matching host. Expression operators may be used in assign where conditions.

Multiple assign where condition can be combined with AND using the && operator as shown in the ssh example:

apply Service "ssh" {
  import "generic-service"

  check_command = "ssh"

  assign where host.address && host.vars.os == "Linux"
}

In this example, the service ssh is applied to all hosts having the address attribute defined AND having the custom attribute os set to the string Linux. You can modify this condition to match multiple expressions by combinding AND and OR using && and || operators, for example assign where host.address && (vars.os == "Linux" || vars.os == "Windows").

A more advanced example is shown by the http and disk service apply rules. While one apply rule for ssh will only create a service for matching hosts, you can go one step further: Generate apply rules based on array items or dictionary key-value pairs.

The idea is simple: Your host in hosts.conf defines the disks dictionary as custom attribute in vars.

Remember the example from hosts.conf:

...

  /* Define disks and attributes for service apply rules in `services.conf`. */
  vars.disks["disk"] = {
    /* No parameters. */
  }
  vars.disks["disk /"] = {
    disk_partition = "/"
  }
...

This dictionary contains multiple service names we want to monitor. disk should just check all available disks, while disk / will pass an additional parameter disk_partition to the check command.

You'll recognize that the naming is important - that's the very same name as it is passed from a service to a check command argument. Read about services and passing check commands in this chapter.

Using apply Service for omits the service name, it will take the key stored in the disk variable in key => config as new service object name.

The for keyword expects a loop definition, for example key => value in dictionary as known from Perl and other scripting languages.

Once defined like this, the apply rule defined below will do the following:

only match hosts with host.vars.disks defined through the assign where condition
loop through all entries in the host.vars.disks dictionary. That's disk and disk / as keys.
call apply on each, and set the service object name from the provided key
inside apply, the generic-service template is imported
defining the disk check command requiring command arguments like disk_partition
adding the config dictionary items to vars. Simply said, there's now vars.disk_partition defined for the generated service

Configuration example:

apply Service for (disk => config in host.vars.disks) {
  import "generic-service"

  check_command = "disk"

  vars += config
}

A similar example is used for the http services. That way you can make your host the information provider for all apply rules. Define them once, and only manage your hosts.

Look into notifications.conf how this technique is used for applying notifications to hosts and services using their type and user attributes.

Don't forget to install the check plugins required by the hosts and services and their check commands.

Further details on the monitoring configuration can be found in the monitoring basics chapter.

users.conf

Defines the icingaadmin User and the icingaadmins UserGroup. The latter is used in hosts.conf for defining a custom host attribute later used in notifications.conf for notification apply rules.

object User "icingaadmin" {
  import "generic-user"

  display_name = "Icinga 2 Admin"
  groups = [ "icingaadmins" ]

  email = "icinga@localhost"
}

object UserGroup "icingaadmins" {
  display_name = "Icinga 2 Admin Group"
}

notifications.conf

Notifications for check alerts are an integral part or your Icinga 2 monitoring stack.

The examples in this file define two notification apply rules for hosts and services. Both apply rules match on the same condition: They are only applied if the nested dictionary attribute notification.mail is set.

Please note that the to keyword is important in notification apply rules defining whether these notifications are applies to hosts or services. The import keyword imports the specific mail templates defined in templates.conf.

The interval attribute is not explicitly set - it defaults to 30 minutes.

By setting the user_groups to the value provided by the respective host.vars.notification.mail attribute we'll implicitely use theicingaadmins UserGroup defined in users.conf.

apply Notification "mail-icingaadmin" to Host {
  import "mail-host-notification"

  user_groups = host.vars.notification.mail.groups

  assign where host.vars.notification.mail
}

apply Notification "mail-icingaadmin" to Service {
  import "mail-service-notification"

  user_groups = host.vars.notification.mail.groups

  assign where host.vars.notification.mail
}

More details on defining notifications and their additional attributes such as filters can be read in this chapter.

commands.conf

This is the place where your own command configuration can be defined. By default only the notification commands used by the notification templates defined in templates.conf.

You can freely customize these notification commands, and adapt them for your needs. Read more on that topic here.

groups.conf

The example host defined in hosts.conf already has the custom attribute os set to Linux and is therefore automatically a member of the host group linux-servers.

This is done by using the group assign expressions similar to previously seen apply rules.

object HostGroup "linux-servers" {
  display_name = "Linux Servers"

  assign where host.vars.os == "Linux"
}

object HostGroup "windows-servers" {
  display_name = "Windows Servers"

  assign where host.vars.os == "Windows"
}

Service groups can be grouped together by similar pattern matches. The match() function expects a wildcard match string and the attribute string to match with.

object ServiceGroup "ping" {
  display_name = "Ping Checks"

  assign where match("ping*", service.name)
}

object ServiceGroup "http" {
  display_name = "HTTP Checks"

  assign where match("http*", service.check_command)
}

object ServiceGroup "disk" {
  display_name = "Disk Checks"

  assign where match("disk*", service.check_command)
}

templates.conf

Most of the example configuration objects use generic global templates by default:

template Host "generic-host" {
  max_check_attempts = 5
  check_interval = 1m
  retry_interval = 30s

  check_command = "hostalive"
}

template Service "generic-service" {
  max_check_attempts = 3
  check_interval = 1m
  retry_interval = 30s
}

The hostalive check command is part of the Plugin Check Commands.

template Notification "mail-host-notification" {
  command = "mail-host-notification"

  states = [ Up, Down ]
  types = [ Problem, Acknowledgement, Recovery, Custom,
            FlappingStart, FlappingEnd,
            DowntimeStart, DowntimeEnd, DowntimeRemoved ]

  period = "24x7"
}

template Notification "mail-service-notification" {
  command = "mail-service-notification"

  states = [ OK, Warning, Critical, Unknown ]
  types = [ Problem, Acknowledgement, Recovery, Custom,
            FlappingStart, FlappingEnd,
            DowntimeStart, DowntimeEnd, DowntimeRemoved ]

  period = "24x7"
}

More details on Notification object attributes can be found here.

downtimes.conf

The load service apply rule defined in services.conf defines the backup_downtime custom attribute.

The ScheduledDowntime apply rule uses this attribute to define the default value for the time ranges required for recurring downtime slots.

apply ScheduledDowntime "backup-downtime" to Service {
  author = "icingaadmin"
  comment = "Scheduled downtime for backup"

  ranges = {
    monday = service.vars.backup_downtime
    tuesday = service.vars.backup_downtime
    wednesday = service.vars.backup_downtime
    thursday = service.vars.backup_downtime
    friday = service.vars.backup_downtime
    saturday = service.vars.backup_downtime
    sunday = service.vars.backup_downtime
  }

  assign where service.vars.backup_downtime != ""
}

timeperiods.conf

This file contains the default timeperiod definitions for 24x7, 9to5 and never. Timeperiod objects are referenced by *period objects such as hosts, services or notifications.

satellite.conf

Includes default templates and dependencies for monitoring remote clients using service discovery and config generation on the master. Can be ignored/removed on setups not using this features.