How To Use the Icinga2 Executor with String Interpolation¶
This advanced How To is intended to help you configure, use and test the Icinga2 Executor in combination with the String Interpolation feature, creating a passive check-only monitoring service result with dynamic generation of the check’s resulting content. The general approach however can be used to dynamically execute Icinga 2 actions (or any other action) based on the content of the event.
Step #1: Prerequisites¶
Tornado:
For testing purposes we will manually send an event to Tornado via the shell. In a production environment, Tornado can accept events from any collector and even via an HTTP POST request with a JSON payload.
Make sure that the username and password are properly set to your dedicated Tornado user in Icinga 2:
/neteye/shared/tornado/conf/icinga2_client_executor.toml
Icinga Director / Icinga 2:
Create a host called host.example.com* with no particular requirements
Create a service template with the following properties:
Check command: dummy
Execute active checks: No
Accept passive checks: Yes
Create a service* called my_dummy on the host host.example.com that imports the previously created service template
Deploy this configuration to Icinga 2
Step #2: Service and Rule Configuration¶
Below is an example of an event that we will use throughout this How To, including sending it to Tornado. For now, keep it handy as you read the next section, since the rules we will configure are based on this specific format:
{
"type": "dummy_passive_check",
"created_ms": 1000,
"payload": {
"hostname": "host.example.com",
"service": "my_dummy",
"exit_status": "2",
"measured": {
"result1": "0.1",
"result2": "98"
}
}
}
Now let’s configure a rule with the following WHERE constraints:
It matches events of type dummy_passive_check
It requires the service name to be my_dummy
It contains the critical exit_code 2
We can achieve this by creating the following rule in
/neteye/shared/tornado/conf/rules.d/, in a file called
900_icinga2_my_checkresult_crit.json:
{
"description": "Set the critical status for my_dummy checks in Icinga 2",
"continue": true,
"active": true,
"constraint": {
"WHERE": {
"type": "AND",
"operators": [
{
"type": "equal",
"first": "${event.type}",
"second": "dummy_passive_check"
},
{
"type": "equal",
"first": "${event.payload.service}",
"second": "my_dummy"
},
{
"type": "equal",
"first": "${event.payload.exit_status}",
"second": "2"
}
]
},
"WITH": {}
},
"actions": []
}
In addition, we want our rule to trigger an Icinga 2 action with a passive check result that:
Applies to the my_dummy service of the host in ${event.payload.hostname}
Sets the exit_status to critical* (=2)
Adds a human readable plugin_output
Adds a machine readable performance_data field with two simple static thresholds:
result1 perfdata: contains imaginary millisecond duration, with 300ms warn and 500ms crit threshold
result2 perfdata: contains imaginary percentages, with 80% warn and 95% crit
Now let’s add these desired actions to the rule above to create this final version:
{
"description": "Set the critical status for my_dummy checks in Icinga 2",
"continue": true,
"active": true,
"constraint": {
"WHERE": {
"type": "AND",
"operators": [
{
"type": "equal",
"first": "${event.type}",
"second": "dummy_passive_check"
},
{
"type": "equal",
"first": "${event.payload.service}",
"second": "my_dummy"
},
{
"type": "equal",
"first": "${event.payload.exit_status}",
"second": "2"
}
]
},
"WITH": {}
},
"actions": [
{
"id": "icinga2",
"payload": {
"icinga2_action_name": "process-check-result",
"icinga2_action_payload": {
"exit_status": "${event.payload.exit_status}",
"plugin_output": "CRITICAL - Result1 is ${event.payload.measured.result1}ms Result2 is ${event.payload.measured.result2}%",
"performance_data": "result_1=${event.payload.measured.result1}ms;300.0;500.0;0.0 result_2=${event.payload.measured.result2}%;80;95;0",
"filter": "host.name==\"${event.payload.hostname}\" && service.name==\"${event.payload.service}\"",
"type": "Service"
}
}
}
]
}
Remember that whenever you create a new rule or edit an existing one, you will need to restart the Tornado service. It is also helpful to run a check to make sure there are no syntactic errors in your new rule:
# tornado --config-dir=/neteye/shared/tornado/conf check
# systemctl restart tornado.service
If you performed all the above steps correctly, you should notice that whenever an event matches the rule, the body of the generated action will no longer contain any of the original placeholders ${event.payload.*}. In fact, they are replaced by the actual values extracted from the event. If one or more placeholders cannot be resolved, the entire action will fail.
Step #3: Send the Event and Set the Status¶
Open a browser and verify that you have deployed the required configuration to Icinga 2. This can be done by navigating to the Overview > Services > host.example.com: my_dummy service (note that this link will not work if you have not followed all the steps above). You should see that it is still in the Pending state as no active checks have been executed.
We can now use the tornado-send-event helper command to send the JSON content of a file to the Tornado API. So now create a file called payload.json with the following content in your home directory:
{
"type": "dummy_passive_check",
"created_ms": 1000,
"payload": {
"hostname": "host.example.com",
"service": "my_dummy",
"exit_status": "2",
"measured": {
"result1": "0.1",
"result2": "98"
}
}
}
Send it to Tornado using the following command:
# tornado-send-event ~/payload.json
This should trigger our rule and produce a response similar to the following:
{
"event": {
"type": "dummy_passive_check",
"created_ms": 1000,
"payload": {
"service": "my_dummy",
"measured": {
"result1": "0.1",
"result2": "98"
},
"exit_status": "2",
"hostname": "host.example.com"
}
},
"result": {
"type": "Rules",
"rules": {
"rules": {
[...omitted...]
"icinga2_my_checkresult_crit": {
"rule_name": "icinga2_my_checkresult_crit",
"status": "Matched",
"actions": [
{
"id": "icinga2",
"payload": {
"icinga2_action_name": "process-check-result",
"icinga2_action_payload": {
"exit_status": "2",
"filter": "host.name==\"host.example.com\" && service.name==\"my_dummy\"",
"performance_data": "result_1=0.1ms;300.0;500.0;0.0 result_2=98%;80;95;0",
"plugin_output": "CRITICAL - Result1 is 0.1ms Result2 is 98%",
"type": "Service"
}
}
}
},
"message": null
],
[...omitted...]
"extracted_vars": {}
}
}
}
Now open your browser and check the service in Icinga 2 again. You’ll see that it has NOT changed yet. This behavior is intentional: in order to avoid triggering actions accidentally, the tornado-send-event command executes no actions by default. We can tell tornado to actually execute the actions by passing the -f flag to the script as follows:
tornado-send-event ~/payload.json -f
Checking the Service once again should now show that it has turned red and its state has become soft critical. Depending on your configuration, after a few additional executions it will end up in the hard critical state.
As you may notice, if we change the exit_code in the event payload to anything other than 2, the rule will no longer match since we filter out everything that is not a critical event. Adding another rule that filters only on OK states (exit_code == 0), and then sets the service state to an OK state, is left as an exercise to the reader.
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