Add Kafka msgpack support

[zerosoul13]

Hello,

When I tried to integrate carbon-relay-ng through Kafka I found that the format produced by carbon-relay-ng is not compatible with go-carbon.

This commit adds support for msgpack format so that, if we (the users) decide to use carbon-relay-ng and Kafka, it works out of the box with go-carbon.

Related issues:

• Does carbon-relay-ng support pure kafka? grafana/carbon-relay-ng#281 (comment)
• kafka messagepack serialisation support #288
• kafkaMdm sending streams in strange encoding format to Kafka grafana/carbon-relay-ng#484

[deniszh]

That's great addition, thanks, @zerosoul13 !
Could you please update vendor directory using go mod vendor ? Thanks!

[deniszh]

Great, it's green now. It's simple enough to merge, but I would wait for day, maybe someone else want to review.

[bom-d-van]

hi @zerosoul13 , it seems the new protocol isn't handled in Kafka.worker?

[zerosoul13]

hi @zerosoul13 , it seems the new protocol isn't handled in Kafka.worker?

The missing line has been added.

[deniszh]

LGTM. What do you think, @bom-d-van ?

@zerosoul13 - as far as I understand you didn't test it in prod, but you had similar patch implemented, as you discussed in #288 (comment) ?

[zerosoul13]

@deniszh I tested this patch on a test environment. I was able to consume from a specific Kafka partition without any issues

[bom-d-van]

hi yeah, it lgtm as well. thanks for the addition.