EventGate will replace EventBus. EventBus does handles DC failovers by prefixing topics in its datacenter with the datacenter name. E.g. in eqiad, mediawiki.revision-create becomes eqiad.mediawiki.revision-create. Topics are replicated between main Kafka clusters, eqiad -> codfw, and codfw -> eqiad.

Since EventBus is managed by puppet, we can easily configure it there with the datacenter name as the topic prefix. EventGate will be deployed via Helm & Kubernetes. We need a way to configure EventGate with current datacenter.

@fselles suggested labels and the k8s DownwardAPI, which would work if we can render the service-runner config.yaml template with values provided by it.