From Kafka upgrade post-mortem:
https://etherpad.wikimedia.org/p/kafka_upgrade_2015-08_postmortem
Include:
- Check Apache Kafka JIRA for known issues...check bugs that affect version in JIRA:
https://archive.apache.org/dist/kafka/0.8.2.1/RELEASE_NOTES.html)
- Stress test to test functionally to see if Varnish-Kafka latency goes up