[Feature Request] Support Alertmanager Webhooks in Cron Monitors

[lforst]

Discussed in getsentry/sentry-javascript#14909

^{Originally posted by alex-souslik-hs January 6, 2025}
Alertmanager sends POST HTTP requests with a specific JSON format as webhooks. This is incompatible with Sentry's monitor upsert API. Supporting those webhooks can allow using Sentry to monitor Alertmanager based pipelines via heartbeats, similarly to other Cron Monitor solutions.

[getsantry]

Routing to @getsentry/product-owners-crons for triage ⏲️

[evanpurkhiser]

I don't think we're going to support an alternative API format any time in the near future. What would probably work here for users who want to use Alertmanager webhooks is to have some light-weight proxy service to translate the webhooks into the cron check-in format.

[Dhouti]

A fix for this does not necessarily mean supporting an alternative format.

Example of a not-so-elegant generic solution via query params: ?ignore-post-body=true

If using query parameters with a curl like request ?status=ok&environment=example the checkin works as expected as a POST request with no data in the body.

Having the ability to ignore the POST body entirely would make this feature request possible.

This issue really isn't the responsibility of Sentry in my opinion, but you are also the path to getting this functional the fastest without customers having to implement a one-off proxy. Would be great to have a workaround here regardless, the proxy is not ideal.