Export traces for eventshub in failed tests

[mgencur]

Changes

• Introduce a new implementation of Emitter that will gather traces for all events in the given namespace when the test fails
• Provide tracing.WithGatherer(t) that can be registered with the Environment when traces are supposed to be gathered
• Export Spans from eventshub on the "sender" side automatically (no need to enable it by flags), similar to the "receiver" side. We export all the relevant information for the event: its Context and also the data.
• Collect traces for the whole namespace when a test fails. This is done during env.Finish() phase of the Environment.
• Instruction in readme on how to inspect/visualize traces

Example log from a failed test that shows gathering the traces:

logger.go:130: 2022-08-01T14:21:43.919+0200	DEBUG	milestone/emitter_log.go:73	ReceiverReadiness Test Finished	{"test": "TestEventsHubReceiverReadiness", "namespace": "test-remowtqp"}
    logger.go:130: 2022-08-01T14:21:43.919+0200	DEBUG	feature/feature.go:78	Feature state: {"name":"ReceiverReadiness","steps":[{"name":"Pre cache sender image","states":"Any","levels":"All","timing":"Setup"},{"name":"Deploy sink","states":"Any","levels":"All","timing":"Setup"},{"name":"Send event","states":"Any","levels":"All","timing":"Requirement"},{"name":"Event received","states":"Stable","levels":"MUST","timing":"Assert"}],"state":null,"refs":null}	{"test": "TestEventsHubReceiverReadiness"}
    logger.go:130: 2022-08-01T14:21:43.919+0200	INFO	milestone/emitter_tracing.go:104	Fetching traces for namespace test-remowtqp	{"test": "TestEventsHubReceiverReadiness"}
2022/08/01 14:21:44 Env variable ARTIFACTS not set. Using artifacts instead.
    logger.go:130: 2022-08-01T14:21:44.348+0200	INFO	milestone/emitter_tracing.go:119	Exporting trace into artifacts/traces/test-remowtqp.json	{"test": "TestEventsHubReceiverReadiness"}
    logger.go:130: 2022-08-01T14:21:44.355+0200	DEBUG	milestone/emitter_log.go:116	Finished: Failed	{"test": "TestEventsHubReceiverReadiness", "namespace": "test-remowtqp"}

This feature requires knative/pkg#2475 to be implemented because the eventshub sender Pod is shutdown immediately after the last event is sent. It means some traces might not be exported to Zipkin in time. The workaround for now is to send at least 2 events with a couple of seconds delay and adjust the test to count with extra events. I have a solution for this issue locally and will be sending a PR to knative/pkg shortly.

/kind enhancement

Fixes #367

Release Note

Docs

[knative-prow]

@mgencur: The label(s) kind/<kind> cannot be applied, because the repository doesn't have them.

In response to this:

Fixes #367

Changes

• Introduce a new implementation of Emitter that will gather traces for all events in the given namespace when the test fails
• Provide tracing.WithGatherer(t) that can be registered with the Environment when traces are supposed to be gathered
• Export Spans from eventshub on the "sender" side automatically (no need to enable it by flags), similar to the "receiver" side. We export all the relevant information for the event: its Context and also the data.
• Collect traces for the whole namespace when a test fails. This is done during env.Finish() phase of the Environment.
• Instruction in readme on how to inspect/visualize traces

This feature requires knative/pkg#2475 to be implemented because the eventshub sender Pod is shutdown immediately after the last event is sent. It means some traces might not be exported to Zipkin in time. The workaround for now is to send at least 2 events with a couple of seconds delay and adjust the test to count with extra events. I have a solution for this issue locally and will be sending a PR to knative/pkg shortly.

/kind

Fixes #

Release Note

Docs

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[pierDipi]

Thanks!

/lgtm
/approve

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: mgencur, pierDipi

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[pierDipi]

It is stuck at

Pending — Not mergeable. Job Unit Test (discovery, knative-sandbox) has not succeeded.

we need something like this for this repository as well: knative/test-infra#3463