Dead Man Switch
The Dead Man Switch (DMS) handler will trigger an alert if an external service has not "checked in" in some time.
More precisely, a separate HTTP server is spawned on which external service can send GET requests to "check in". These services would usually check in after performing some task successfully (like a backup process, for instance) to let Defcon know the task finished successfully. If a check in is missed, this would indicate the task has failed, triggering an alert.
Attributes
| Attribute | Type | Example | Description |
|---|---|---|---|
kind | string | "deadmanswitch" | - |
stale_after | string | "1h" | The duration after which to create an outage if no check in happened |
Configuration
The DMS_ENABLE can be used to disable the HTTP server used to receive checkins. Additionally, its listening address (127.0.0.1:8080 by default) can be configured through DMS_LISTEN.
To check in, a service needs to perform a GET request at http://${LISTEN_ADDRESS}/checkin/<check_id>.