Move alertmanager-proxy port to 9095

[paulfantom]

Needed to merge openshift/prometheus-operator#35 as we need to move alertmanager-proxy to not be on port 9094.

/cc @brancz @lilic @s-urbaniak

[s-urbaniak]

/lgtm

[openshift-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: paulfantom, s-urbaniak

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [paulfantom,s-urbaniak]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[brancz]

Would it be possible to instead of changing the port to just bind against the pod ip? Alertmanager binds against localhost iirc. I feel that would be a less breaking and less unexpected setup.

[s-urbaniak]

ping @paulfantom can you comment on #411 (comment)?

[brancz]

For context, we've had bugs opened for similar changes, and this one is rather extreme, as if someone integrated with the alertmanager endpoints (which we actively encourage), then we've just broken their alerting pipeline.

[paulfantom]

We can roll it back and even provide backwards compatibility by forcing alertmanager to advertise gossip not on port 9094 but on 6783 by using --cluster.listen-address alertmanager parameter. However this would need some changes in prometheus-operator, so maybe you are right and let's just bind against the pod ip.

I didn't want to have two different things on port with the same number as this might be confusing.