Support Jaeger tracing backends

[haubenr]

At the moment knative only supports tracing to Zipkin backends. It would be good to have more options, e.g. supporting Jaeger tracing backends as well (natively, without the need of external converters etc.)

/area API /kind feature

Expected Behavior

knative support Jaeger tracing backends.

Actual Behavior

knative only supports tracing to Zipkin backends.

Steps to Reproduce the Problem

n/a

Additional Info

This issue is a follow-up to these issues that have been closed due to inactivity:

https://github.com/knative/pkg/issues/1076 https://github.com/knative/pkg/issues/1077

[knative-prow[bot]]

@haubenr: The label(s) area/tracing cannot be applied, because the repository doesn't have them.

In response to [this](https://github.com/knative/pkg/issues/2561): >At the moment knative only supports tracing to Zipkin backends. It would be good to have more options, e.g. supporting Jaeger tracing backends as well (natively, without the need of external converters etc.) > >/area tracing >/kind feature > >## Expected Behavior > >knative support Jaeger tracing backends. > >## Actual Behavior > >knative only supports tracing to Zipkin backends. > >## Steps to Reproduce the Problem > >n/a > >## Additional Info > >This issue is a follow-up to these issues that have been closed due to inactivity: > >https://github.com/knative/pkg/issues/1076 >https://github.com/knative/pkg/issues/1077 > Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes/test-infra](https://github.com/kubernetes/test-infra/issues/new?title=Prow%20issue:) repository.

[dprotaso]

I think I'd like to support jaeger by exporting Otel traces. Jaeger as of 1.35 can directly receive them.

We do need an OpenCensus => OTel exporter - which seems to have existed before but was removed

I prodded the issue here to see if it's unblocked & possible to add back a tracing bridge

https://github.com/open-telemetry/opentelemetry-go/issues/2808

edit looks like the tracing bridge still exists

https://github.com/open-telemetry/opentelemetry-go/tree/main/bridge/opencensus

[dprotaso]

Note: we want to eventually swap to OTel instead of OpenCensus https://github.com/knative/pkg/issues/855

[haubenr]

Sure, sounds like the right move.

[github-actions[bot]]

This issue is stale because it has been open for 90 days with no activity. It will automatically close after 30 more days of inactivity. Reopen the issue with /reopen. Mark the issue as fresh by adding the comment /remove-lifecycle stale.

[knative-prow-robot]

This issue or pull request is stale because it has been open for 90 days with no activity.

This bot triages issues and PRs according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
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You can:

• Mark this issue or PR as fresh with /remove-lifecycle rotten
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/lifecycle stale

[dprotaso]

/lifecycle frozen