The cluster name can be configured by setting the `DISCOURSE_CLUSTER_NAME` environment variable. If set, you can then call /srv/status with a `?cluster=` parameter. If the cluster does not match, an error will be returned. This is useful if you need a load balancer to be able to verify the identity, as well as the presence, of an application container.
This can cause unbound CPU usage in some cases, and excessive logging in other cases. This commit moves redis readonly information into the local process, but maintains the DistributedCache for postgres readonly state.
