[Fn][Observability] Status of OpenTelemetry metrics support (PIP-264/PIP-320)

[Dream95]

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• I searched in the issues and found nothing similar.

Motivation

Background

Per PIP-264 and PIP-320 , it looks like Pulsar Functions metrics are still not integrated with OpenTelemetry in practice.
Function Worker has PulsarWorkerOpenTelemetry creating a Meter, but Functions-related OTel metrics are not registered/emitted yet .

Question

Could someone clarify the current status of OpenTelemetry metrics for Pulsar Functions?

• If nobody is actively working on it, I’m happy to contribute.

Solution

No response

Alternatives

No response

Anything else?

No response

Are you willing to submit a PR?

• I'm willing to submit a PR!

[lhotari]

Could someone clarify the current status of OpenTelemetry metrics for Pulsar Functions?

• If nobody is actively working on it, I’m happy to contribute.

@Dream95 Contributions are definitely welcome in this area. We'd like to cover Pulsar Functions OTel support for Pulsar 5.0.0-M2.

[Dream95]

@lhotari I drafted a design for Functions OpenTelemetry metrics. It builds on the Function metrics section in PIP-264 and the Worker scaffolding from PIP-320. PulsarWorkerOpenTelemetry is already there, but no Function metrics are registered on it yet.

One question: PIP-264 treats Function metrics as sub-PIP work. Should this go in as a new sub-PIP, or can it continue under PIP-264 / PIP-320 as follow-up PRs without a separate document?