I filed a GitHub issue: https://github.com/cloudfoundry/cf-registrar/issues/7

What is happening was that
- NATS receives route registration from CC and Traffic Controller
- UAA not sending route registration to NATS, so UAA's routes are missing from gorouter
- UAA's cf registrar stuck after following (instead of sending route registration messages):
Connected to NATS - varz registration
Announcing start up vcap.component.announce

bosh vms, bosh cck, and monit all saying that everything running.

Any suggestion on how to troubleshoot this? What are the possible reasons cf-registrar not sending route.register messages?

What version of cf-release? If it's recent, see the "Important" section of
the release notes about colocating the new route_registrar for v217 and
v218.

https://github.com/cloudfoundry/cf-release/releases/tag/v218

Amit