Using a Producer from the current trunk (a6691fb79), I'm unable to produce data to a 2.2 broker.
tl;dr;, I narrowed down the problem to https://github.com/apache/kafka/commit/a42f16f98 . My hypothesis is that some part of that commit broke backward compatibility with older brokers.
I'm using this Producer config:
- create a simple Producer to produce test data to a broker
- build against commmit a42f16f98
- start an older broker. (I was using 2.1, and someone else reproduced it with 2.2)
- run your producer and note that it doesn't produce data (seems to hang, I see it produce 2 records in 1 minute)
- build against the predecessor commit 65aea1f36
- run your producer and note that it DOES produce data (I see it produce 1M records every 15 second)
I've also confirmed that if I check out the current trunk (a6691fb79e2c55b3) and revert a42f16f98, I also observe that it produces as expected (1M every 15 seconds).