Feature: HTTP Config Additional Headers

[therealgambo]

As slightly touched on in prometheus/prometheus#4314 having the ability to provide custom headers for webhooks would solve any bespoke integration with 3rd party API's that do not conform to strict authorization formats.

[brian-brazil]

The alertmanager webhook is intended to be used by something specifically designed to accept a webhook, not to be able to talk to arbitrary http-based protocols. If you need this you should write a webhook receiver that speaks the protocol that you need.

This code is also used in several other places, allowing headers to be added would be problematic for them.

[therealgambo]

We're not actively adding new receivers, we recommend implementing custom notification integrations via the webhook receiver.

Boldly noted in the documentation, or is this no longer the case? I'm not going to put in the work for it to be blindly disregarded.

Also, if that isn't the case, can we re-open prometheus/alertmanager#444 for review and merge?

[brian-brazil]

That's still the case.

I don't see how that makes a difference for that PR. The reasons for rejecting it remain valid.

[simonpasquier]

Closing it as the original issue was because OpsGenie didn't support standard HTTP authorization headers. This is no longer true, see prometheus/alertmanager#444 (comment).