# Configuration: First Steps <a id="configuration"></a>

This chapter provides an introduction into best practices for your Icinga 2 configuration.
The configuration files which are automatically created when installing the Icinga 2 packages
are a good way to start with Icinga 2.

The [Language Reference](17-language-reference.md#language-reference) chapter explains details
on value types (string, number, dictionaries, etc.) and the general configuration syntax.

## Configuration Best Practice <a id="configuration-best-practice"></a>

If you are ready to configure additional hosts, services, notifications,
dependencies, etc., you should think about the requirements first and then
decide for a possible strategy.

There are many ways of creating Icinga 2 configuration objects:

* Manually with your preferred editor, for example vi(m), nano, notepad, etc.
* A configuration tool for Icinga 2 e.g. the [Icinga Director](https://github.com/Icinga/icingaweb2-module-director)
* Generated by a [configuration management tool](13-addons.md#configuration-tools) such as Puppet, Chef, Ansible, etc.
* A custom exporter script from your CMDB or inventory tool
* etc.

Find the best strategy for your own configuration and ask yourself the following questions:

* Do your hosts share a common group of services (for example linux hosts with disk, load, etc. checks)?
* Only a small set of users receives notifications and escalations for all hosts/services?

If you can at least answer one of these questions with yes, look for the
[apply rules](03-monitoring-basics.md#using-apply) logic instead of defining objects on a per
host and service basis.

* You are required to define specific configuration for each host/service?
* Does your configuration generation tool already know about the host-service-relationship?

Then you should look for the object specific configuration setting `host_name` etc. accordingly.

You decide on the "best" layout for configuration files and directories. Ensure that
the [icinga2.conf](04-configuration.md#icinga2-conf) configuration file includes them.

Consider these ideas:

* tree-based on locations, host groups, specific host attributes with sub levels of directories.
* flat `hosts.conf`, `services.conf`, etc. files for rule based configuration.
* generated configuration with one file per host and a global configuration for groups, users, etc.
* one big file generated from an external application (probably a bad idea for maintaining changes).
* your own.

In either way of choosing the right strategy you should additionally check the following:

* Are there any specific attributes describing the host/service you could set as `vars` custom variables?
You can later use them for applying assign/ignore rules, or export them into external interfaces.
* Put hosts into hostgroups, services into servicegroups and use these attributes for your apply rules.
* Use templates to store generic attributes for your objects and apply rules making your configuration more readable.
Details can be found in the [using templates](03-monitoring-basics.md#object-inheritance-using-templates) chapter.
* Apply rules may overlap. Keep a central place (for example, [services.conf](04-configuration.md#services-conf) or [notifications.conf](04-configuration.md#notifications-conf)) storing
the configuration instead of defining apply rules deep in your configuration tree.
* Every plugin used as check, notification or event command requires a `Command` definition.
Further details can be looked up in the [check commands](03-monitoring-basics.md#check-commands) chapter.

If you are planning to use a distributed monitoring setup with master, satellite and client installations
take the configuration location into account too. Everything configured on the master, synced to all other
nodes? Or any specific local configuration (e.g. health checks)?

There is a detailed chapter on [distributed monitoring scenarios](06-distributed-monitoring.md#distributed-monitoring-scenarios).
Please ensure to have read the [introduction](06-distributed-monitoring.md#distributed-monitoring) at first glance.

If you happen to have further questions, do not hesitate to join the
[community support channels](https://icinga.com/community/)
and ask community members for their experience and best practices.

## Your Configuration <a id="your-configuration"></a>

If you prefer to organize your own local object tree, you can also remove
`include_recursive "conf.d"` from your icinga2.conf file.

Create a new configuration directory, e.g. `objects.d` and include it
in your icinga2.conf file.

```
[root@icinga2-master1.localdomain /]# mkdir -p /etc/icinga2/objects.d

[root@icinga2-master1.localdomain /]# vim /etc/icinga2/icinga2.conf

/* Local object configuration on our master instance. */
include_recursive "objects.d"
```

This approach is used by the [Icinga 2 Puppet module](https://github.com/Icinga/puppet-icinga2).

If you plan to setup a distributed setup with HA clusters and clients, please refer to [this chapter](#06-distributed-monitoring.md#distributed-monitoring-top-down)
for examples with `zones.d` as configuration directory.

## Configuration Overview <a id="configuring-icinga2-overview"></a>

### icinga2.conf <a id="icinga2-conf"></a>

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](17-language-reference.md#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](10-icinga-template-library.md#icinga-template-library) provides a set of common templates
and [CheckCommand](03-monitoring-basics.md#check-commands) definitions.

```
/**
* 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>
include <plugins-contrib>
include <manubulon>

/**
* This includes the Icinga 2 Windows plugins. These command definitions
* are required on a master node when a client is used as command endpoint.
*/
include <windows-plugins>

/**
* This includes the NSClient++ check commands. These command definitions
* are required on a master node when a client is used as command endpoint.
*/
include <nscp>

/**
* 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](11-cli-commands.md#enable-features) for more details.

```
/**
* 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](04-configuration.md#conf-d) directory. This
directive makes sure that all of your own configuration files are included.

### constants.conf <a id="constants-conf"></a>

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](02-installation.md#setting-up-check-plugins) are installed.
This constant is used by a number of
[built-in check command definitions](10-icinga-template-library.md#icinga-template-library).
* 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.

### zones.conf <a id="zones-conf"></a>

This file can be used to specify the required [Zone](09-object-types.md#objecttype-zone)
and [Endpoint](09-object-types.md#objecttype-endpoint) configuration object for
[distributed monitoring](06-distributed-monitoring.md#distributed-monitoring).

By default the `NodeName` and `ZoneName` [constants](04-configuration.md#constants-conf) will be used.

It also contains several [global zones](06-distributed-monitoring.md#distributed-monitoring-global-zone-config-sync)
for distributed monitoring environments.

Please ensure to modify this configuration with real names i.e. use the FQDN
mentioned in [this chapter](06-distributed-monitoring.md#distributed-monitoring-conventions)
for your `Zone` and `Endpoint` object names.

### The conf.d Directory <a id="conf-d"></a>

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](04-configuration.md#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](04-configuration.md#icinga2-conf) file.

> **Note**
>
> You can remove the include directive in [icinga2.conf](04-configuration.md#icinga2-conf)
> 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](04-configuration.md#configuration-best-practice).

Available configuration files which are installed by default:

* [hosts.conf](04-configuration.md#hosts-conf)
* [services.conf](04-configuration.md#services-conf)
* [users.conf](04-configuration.md#users-conf)
* [notifications.conf](04-configuration.md#notifications-conf)
* [commands.conf](04-configuration.md#commands-conf)
* [groups.conf](04-configuration.md#groups-conf)
* [templates.conf](04-configuration.md#templates-conf)
* [downtimes.conf](04-configuration.md#downtimes-conf)
* [timeperiods.conf](04-configuration.md#timeperiods-conf)
* [api-users.conf](04-configuration.md#api-users-conf)
* [app.conf](04-configuration.md#app-conf)

#### hosts.conf <a id="hosts-conf"></a>

The `hosts.conf` file contains an example host based on your
`NodeName` setting in [constants.conf](04-configuration.md#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 variables which are available
for check and notification commands. Most of the [Plugin Check Commands](10-icinga-template-library.md#icinga-template-library)
in the Icinga Template Library require an `address` attribute.

The custom variable `os` is evaluated by the `linux-servers` group in
[groups.conf](04-configuration.md#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](04-configuration.md#services-conf).
* define disks (all, specific `/`) and their attributes for the `disk`
service apply rule defined in [services.conf](04-configuration.md#services-conf).
* define notification types (`mail`) and set the groups attribute. This
will be used by notification apply rules in [notifications.conf](04-configuration.md#notifications-conf).

If you've installed [Icinga Web 2](02-installation.md#setting-up-icingaweb2), you can
uncomment the http vhost attributes and reload Icinga 2. The apply
rules in [services.conf](04-configuration.md#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 variable `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](04-configuration.md#services-conf) applied.

> **Tip**
>
> If you don't understand all the attributes and how to use [apply rules](17-language-reference.md#apply),
> don't worry -- the [monitoring basics](03-monitoring-basics.md#monitoring-basics) chapter will explain
> that in detail.

#### services.conf <a id="services-conf"></a>

These service [apply rules](17-language-reference.md#apply) 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 variable `http_vhosts` defined as dictionary.
`disk`, `disk /`                            | All hosts with custom variable `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)](10-icinga-template-library.md#icinga-template-library) while `http_ip`, `ssh`, `load`, `processes`,
`users` and `disk` are all provided by the [Plugin Check Commands](10-icinga-template-library.md#icinga-template-library)
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 variable `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](04-configuration.md#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](17-language-reference.md#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 variable `os` set to the string
`Linux`.
You can modify this condition to match multiple expressions by combining `AND`
and `OR` using `&&` and `||` [operators](17-language-reference.md#expression-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](04-configuration.md#hosts-conf) defines the
`disks` dictionary as custom variable in `vars`.

Remember the example from [hosts.conf](04-configuration.md#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](03-monitoring-basics.md#command-passing-parameters).

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](10-icinga-template-library.md#plugin-check-command-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](04-configuration.md#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](02-installation.md#setting-up-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](03-monitoring-basics.md#monitoring-basics) chapter.

#### users.conf <a id="users-conf"></a>

Defines the `icingaadmin` User and the `icingaadmins` UserGroup. The latter is used in
[hosts.conf](04-configuration.md#hosts-conf) for defining a custom host attribute later used in
[notifications.conf](04-configuration.md#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 <a id="notifications-conf"></a>

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](03-monitoring-basics.md#using-apply-notifications)
defining whether these notifications are applies to hosts or services.
The `import` keyword imports the specific mail templates defined in [templates.conf](04-configuration.md#templates-conf).

The `interval` attribute is not explicitly set -- it [defaults to 30 minutes](09-object-types.md#objecttype-notification).

By setting the `user_groups` to the value provided by the
respective [host.vars.notification.mail](04-configuration.md#hosts-conf) attribute we'll
implicitely use the `icingaadmins` UserGroup defined in [users.conf](04-configuration.md#users-conf).

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

  user_groups = host.vars.notification.mail.groups
  users = host.vars.notification.mail.users

  assign where host.vars.notification.mail
}

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

  user_groups = host.vars.notification.mail.groups
  users = host.vars.notification.mail.users

  assign where host.vars.notification.mail
}
```

More details on defining notifications and their additional attributes such as
filters can be read in [this chapter](03-monitoring-basics.md#alert-notifications).

#### commands.conf <a id="commands-conf"></a>

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](04-configuration.md#templates-conf).

You can freely customize these notification commands, and adapt them for your needs.
Read more on that topic [here](03-monitoring-basics.md#notification-commands).

#### groups.conf <a id="groups-conf"></a>

The example host defined in [hosts.conf](hosts-conf) already has the
custom variable `os` set to `Linux` and is therefore automatically
a member of the host group `linux-servers`.

This is done by using the [group assign](17-language-reference.md#group-assign) expressions similar
to previously seen [apply rules](03-monitoring-basics.md#using-apply).

```
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](18-library-reference.md#global-functions-match) 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 <a id="templates-conf"></a>

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](10-icinga-template-library.md#icinga-template-library).

```
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](09-object-types.md#objecttype-notification).


#### downtimes.conf <a id="downtimes-conf"></a>

The `load` service apply rule defined in [services.conf](04-configuration.md#services-conf) defines
the `backup_downtime` custom variable.

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

Learn more about downtimes in [this chapter](08-advanced-topics.md#downtimes).

```
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 <a id="timeperiods-conf"></a>

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.


#### api-users.conf <a id="api-users-conf"></a>

Provides the default [ApiUser](09-object-types.md#objecttype-apiuser) object
named "root" for the [API authentication](12-icinga2-api.md#icinga2-api-authentication).

#### app.conf <a id="app-conf"></a>

Provides the default [IcingaApplication](09-object-types.md#objecttype-icingaapplication)
object named "app" for additional settings such as disabling notifications
globally, etc.
