GROUP-103 Auto-delete Consumer Queues After Shutdown

[makmn1]

Description of Changes

In a recent update, Group Sync instances were assigned a unique consumer queue to the group event exchange on RabbitMQ. This was configured through Spring Cloud Stream. The issue with this is those queues aren't deleted after the application is shutdown. Since those queues are unique to the instance that create them, they then accumulate messages until the memory limit has been exceeded.

The following configuration change has been added:

spring:
  cloud:
    stream:
      rabbit:
        bindings:
          processedEvents-in-0:
            consumer:
              anonymous-group-prefix: ${spring.application.name}

This change adds configuration specific to using the RabbitMQ binder to create an anonymous queue, which according to the Spring RabbitMQ docs:

anonymousGroupPrefix
When the binding has no group property, an anonymous, auto-delete queue is bound to the destination exchange. The default naming stragegy for such queues results in a queue named anonymous.<base64 representation of a UUID>. Set this property to change the prefix to something other than the default.
Default: anonymous..

This also meant having to remove the group property for the consumer queue in the Spring Cloud Stream configuration:

spring:
  cloud:
    stream:
      bindings:
          destination: group-event-results
          group: ${spring.application.name}-${random.value} # This line removed

Once this change goes into place, the pods will be restarted. Their old queues will be deleted manually via the RabbitMQ Admin dashboard in production, which isn't too bad since there are only two.