enhancement(codecs): add influx line protocol serializer

[elohmeier]

Summary

Extracted the Influx Line Protocol serialization code into the codecs module and added support for the http/websocket sinks to use it. This enables neat features like being able to use the Grafana Live feature. E.g. with the Vector config below I was able to stream the Vector metrics into Grafana.

To test this you can start a Grafana instance via docker run --rm -p 3000:3000 --name=grafana grafana/grafana and then on http://localhost:3000/org/serviceaccounts create a service account (I just gave it admin access) and then create a token for the Bearer authentication. You can then query metrics from the integrated -- Grafana -- data source (see the screenshot below).

The functionality in Grafana to query this data is currently quite limited but I think this might still be useful for quickly plotting and exploring data e.g. during development of a Vector configuration file.

Vector configuration

sources:
  vector_metrics:
    type: internal_metrics
sinks:
  grafana:
    type: websocket
    inputs:
      - vector_metrics
    uri: ws://127.0.0.1:3000/api/live/push/vector
    encoding:
      codec: influxdb
    auth:
      strategy: bearer
      token: glsa_...

How did you test this PR?

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the no-changelog label to this PR.

References

Notes

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[pront]

Hi @elohmeier, can you fix the merge conflicts with origin/master?

[elohmeier]

Hi @pront, thanks for your review! I'm not sure what to split out into a chore PR here, as this extracts and extends the line protocol encoding logic from the sink into a standalone codec in lib/codecs. I've therefore removed the generated docs on purpose to make it clearer to review and split the change into two commits. Also rebased.