icinga2/doc/3.02-commands.md

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## Commands
Icinga 2 uses three different command object types to specify how
checks should be performed, notifications should be sent and
events should be handled.
> **Note**
>
> Define the `$plugindir$` macro in your global `IcingaMacros` variable
> (located in `/etc/icinga2/conf.d/macros.conf` by default) and use
> it in all your command object definitions.
> Put your plugins and scripts into the directory defined by the `$plugindir$` macro
> and make sure they are executable by the Icinga 2 user.
### Environment Macros
If your plugins require environment macros instead of command arguments you have
to define all macros in the `export_macros` attribute as list.
export_macros = [
"HOSTNAME",
"SERVICEDESC",
"SERVICESTATE"
]
> **Note**
>
> Use templates to define global `export_macros` attributes for the three
> command types and let each command object inherit the attribute.
### Check Commands
`CheckCommand` objects define the command line how a check is called.
> **Note**
>
> `CheckCommand` objects require the ITL template `plugin-check-command`
> to support native plugin based check methods.
Unless you have done so already, download your check plugin and put it
into the `$plugindir$` directory. The following example uses the
`check_disk` plugin shipped with the Nagios Plugins package.
The plugin path and all command arguments are made a list of
double-quoted string arguments for proper shell escaping.
Call the `check_disk` plugin with the `--help` parameter to see
all available options. Our example defines warning (`-w`) and
critical (`-c`) thresholds for the disk usage. Without any
partition defined (`-p`) it will check all local partitions.
Define the default check command macros `wfree` and `cfree` (freely
definable naming schema) and their default threshold values. You can
then use these macros in the command line.
> **Note**
>
> The default macros can be overridden by the macros defined in
> the service using the check command `disk`. The macros can also
> be inherited from a parent template using additive inheritance (`+=`).
object CheckCommand "disk" inherits "plugin-check-command" {
command = [
"$plugindir$/check_disk",
"-w", "$wfree$%",
"-c", "$cfree$%"
],
macros += {
wfree = 20,
cfree = 10,
}
}
The host `localhost` with the service `disk` checks all disks with modified
macros (warning thresholds at `10%`, critical thresholds at `5%` free disk
space).
object Host "localhost" inherits "generic-host" {
services["disk"] = {
templates = [ "generic-service" ],
check_command = "disk",
macros += {
wfree = 10,
cfree = 5
}
},
macros = {
address = "127.0.0.1",
address6 = "::1",
},
}
### Notification Commands
`NotificationCommand` objects define how notifications are delivered to external
interfaces (E-Mail, XMPP, IRC, Twitter, etc).
> **Note**
>
> `NotificationCommand` objects require the ITL template `plugin-notification-command`
> to support native plugin-based notifications.
Below is an example using runtime macros from Icinga 2 (such as `$SERVICEOUTPUT$` for
the current check output) sending an email to the user(s) associated with the
notification itself (`email` macro attribute provided as `$USERMACRO$`).
If you require default macro definitions, you can add a macro dictionary as shown for the
`CheckCommand` object.
object NotificationCommand "mail-service-notification" inherits "plugin-notification-command" {
command = [ (IcingaSysconfDir + "/icinga2/scripts/mail-notification.sh") ],
export_macros = [
"NOTIFICATIONTYPE",
"SERVICEDESC",
"HOSTALIAS",
"HOSTADDRESS",
"SERVICESTATE",
"LONGDATETIME",
"SERVICEOUTPUT",
"NOTIFICATIONAUTHORNAME",
"NOTIFICATIONCOMMENT",
"HOSTDISPLAYNAME",
"SERVICEDISPLAYNAME",
"USEREMAIL"
]
}
The command attribute in the `mail-service-notification` command refers to the following
shell script. The macros specified in the `export_macros` array are exported
as environment variables and can be used in the notification script:
#!/usr/bin/env bash
template=$(cat <<TEMPLATE
***** Icinga *****
Notification Type: $NOTIFICATIONTYPE
Service: $SERVICEDESC
Host: $HOSTALIAS
Address: $HOSTADDRESS
State: $SERVICESTATE
Date/Time: $LONGDATETIME
Additional Info: $SERVICEOUTPUT
Comment: [$NOTIFICATIONAUTHORNAME] $NOTIFICATIONCOMMENT
TEMPLATE
)
/usr/bin/printf "%b" $template | mail -s "$NOTIFICATIONTYPE - $HOSTDISPLAYNAME - $SERVICEDISPLAYNAME is $SERVICESTATE" $USEREMAIL
> **Best Practice**
>
> While it's possible to specify the entire notification command right
> in the NotificationCommand object it is generally advisable to create a
> shell script in the `/etc/icinga2/scripts` directory and have the
> NotificationCommand object refer to that.
### Event Commands
Unlike notifications event commands are called on every service state change
if defined. Therefore the `EventCommand` object should define a command line
evaluating the current service state and other service runtime attributes
available through runtime macros. Runtime macros such as `$SERVICESTATETYPE$`
and `$SERVICESTATE$` will be processed by Icinga 2 helping on fine-granular
events being triggered.
Common use case scenarios are a failing HTTP check requiring an immediate
restart via event command, or a an application is locked and requires
a restart on detection.
> **Note**
>
> `EventCommand` objects require the ITL template `plugin-event-command`
> to support native plugin based checks.
The example below is fictive and not necessarily meant for production use.
When the event command is triggered on a service state change, it will
send a check result using the `process_check_result` script forcibly
changing the service state back to `OK` (`-r 0`) providing some debug
information in the check output (`-o`).
object EventCommand "plugin-event-process-check-result" inherits "plugin-event-command" {
command = [
"$plugindir$/process_check_result",
"-H",
"$HOSTNAME$",
"-S",
"$SERVICEDESC$",
"-c",
"/var/run/icinga2/cmd/icinga2.cmd",
"-r",
"0",
"-o",
"Event Handler triggered in state '$SERVICESTATE$' with output '$SERVICEOUTPUT$'."
]
}