otelcol/exporter/kafka: key jaeger messages on traceid

[kjetijor]

Description: exporter/kafkaexporter: key jaeger spans by traceid, emulating jaeger-collector behavior. This allows for "grouping by traceid" for kafka consumers. For reference: jaeger kafka producer.

Link to tracking Issue: N/A

Testing: Updated tests, inspected resulting messages produced into kafka to match up with the expectation.

Documentation: Updated kafkaexporter documentation to reflect behavior

[linux-foundation-easycla]

The committers are authorized under a signed CLA.

• ✅ Kjetil Jørgensen (9057e0a)

[codecov]

Codecov Report

Merging #2855 (9057e0a) into main (c8bc12e) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #2855   +/-   ##
=======================================
  Coverage   92.04%   92.04%           
=======================================
  Files         278      278           
  Lines       15432    15434    +2     
=======================================
+ Hits        14204    14206    +2     
  Misses        845      845           
  Partials      383      383           

Impacted Files	Coverage Δ
exporter/kafkaexporter/marshaller.go	100.00% <ø> (ø)
exporter/kafkaexporter/jaeger_marshaller.go	86.36% <100.00%> (+0.64%)	⬆️
exporter/kafkaexporter/kafka_exporter.go	100.00% <100.00%> (ø)

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[bogdandrutu]

/cc @jpkrohling

[jpkrohling]

I might take a while to review this one, if any other Jaeger maintainers feel like they can review this one, I'll give my approval by proxy :-)

cc @albertteoh, @joe-elliott

[albertteoh]

lgtm

[bogdandrutu]

Is this a breaking change? Should we protect by a config flag?

[kjetijor]

@bogdandrutu

Is this a breaking change? Should we protect by a config flag?

I do not believe this to be a breaking change. While, this does affect placement of messages into kafka partitions, for all practical purposes we go from random to slightly less random.

[jpkrohling]

Approving based on the review from @albertteoh