1. Proposed title of this feature request

Alertmanager does not use the proxy environment variables

2. What is the nature and description of the request?

Only the Alertmanager proxy sidecar container has the proxy environment variables. We can reach our endpoint from that container but not from the Alertmanager container itself.

3. Why does the customer need this? (List the business requirements here)

We would like to sent our Alertmanager alerts to a webhook receiver which is a Rocket.Chat instance that is accessed via an internet address.

We are using the "proxy_url" setting in the alertmanager.yaml (https://prometheus.io/docs/alerting/latest/configuration/#http_config) as a workaround for now. But we don't like that we have to do redundant proxy configuration while the cluster already has all the information.

In parallel we also created a GitHub issue in the operator repository:

https://github.com/openshift/cluster-monitoring-operator/issues/1074

4. List any affected packages or components.

Alertmanager