VOL-2098 Support for Kafka liveness testing

* Adds liveness channel to sarama_client and kafka_interadapter proxy.
The liveness channel will push true or false to the channel on
each successful or failed Kafka publish.

* Adds support to make a "liveness publish attempt", which publishes
an empty message on a _liveness channel.

* Adds ServiceStatusNotReady to Probe

* Suppresses multiple Probe.UpdateStatus of the same status

* Adds the ability to attach a Probe to the grpc server, so that
when the probe returns NotReady, the Server responds to requests
with UNAVAILABLE.

Change-Id: I996c719570a50f2f6f397887d10d489608269c3f
10 files changed
tree: 4adea62f69c7e6f03a5cc53a112f16057a53b38e
  1. .gitignore
  2. .gitreview
  3. Makefile
  4. VERSION
  5. go.mod
  6. go.sum
  7. pkg/
  8. vendor/