1. Function
The PagerDuty incident management platform can receive messages from a wide variety of sources and process them further — for example by filtering, sending notifications or initiating escalations. Notifications from Checkmk can be easily forwarded to the platform via a so-called integration key.
2. Configuring PagerDuty
PagerDuty provides integrations for many popular tools, including Checkmk. All you need is an Integration Key, which you create under PagerDuty as follows:
Create a new service or open an existing one.
In the corresponding service create a new integration via the Integrations tab.
Assign any name and for the Integration Type choose Check_MK.
Copy the created Integration Key.
3. Configuration in Checkmk
You have already learned how to set up Checkmk notifications in general in the article about notifications.
As a reminder:
You can not only specify individual users and contact groups as recipients of the notifications. Instead, you can also define a ticket system or an event engine as the target of the notifications, for example. However, you must then take two factors into account when creating the notification rules:
Only a single user may be entered as a contact, i.e. neither a contact group nor an object contact, otherwise several notifications will be sent to the target system for each event.
If the first point is fulfilled, but this user is used in several notification rules that are of the same type (e.g. ServiceNow), then only the last rule applies in each case. It is therefore advisable to create a separate functional user for each of these notification rules.
In Checkmk the integration now requires only the specification of the integration key:
For the Notification Method choose PagerDuty.
Enter the copied key under Integration Key.

The filtering of the generated notifications can be implemented either in Checkmk, or in PagerDuty via the Event Rules. You can also optionally switch the PagerDuty connection to your own Checkmk user account. Simply create a standard user with a disabled login, and then create a personal notification rule.
For testing you can use the Fake check results and Custom notification commands and set a host covered by the rule to DOWN.