Clarify the situation with support for Prometheus PushGateway and the deprecated simpleclient

[breun]

Spring Boot 3.4's Prometheus documentation says:

The Prometheus Pushgateway only works with the deprecated Prometheus simpleclient for now, until the Prometheus 1.x client adds support for it.

The Prometheus 1.x client added PushGateway support in version 1.3.0, so the blocker mentioned above is gone. I think it would be good to update this documentation note to reflect that.

Also, I don't believe the PushGateway support in the Prometheus 1.x client gets auto-configured yet, so I think this still needs to be added in Spring Boot 3.4?

[wilkinsona]

We've added support in Spring Boot 3.5. That won't be back ported to 3.4 as we consider it to be a new feature and we don't back port new features to maintenance branches.

We can use this issue to clarify the documentation.

[breun]

@wilkinsona Thanks for your reply. I see the milestone has been set to 3.3.x, but I think this should be 3.4.x?

[wilkinsona]

It's applicable to 3.3.x as well because its documentation contains the same note.