PingSource tracing doesn't work anymore

[daisy-ycguo]

Describe the bug

After doing configuration accord to the document, no tracing is reported from PingSource.

Expected behavior PingSource should report tracing which should be viewed from zipkin.

To Reproduce

1. Set up pingsource following the guidance
2. Set up tracing following the guidance
3. Set up zipkin according to the guidance
4. Go to the web interface of zipkin, and we will not find any tracing of pingsource

Knative release version the main branch

Additional context I did a debug and located the cause. The issue is caused by both SetupDynamicPublishing in knative-dev/pkg/tracing/setup.go and SetupTracing in eventing/pkg/adapter/v2/configurator_configmap.go.

SetupDynamicPublishing should call oct.ApplyConfig(cfg) at the first time. Since it doesn't call ApplyConfig(cfg), the tracing configuration only takes effect when configmap config-tracing is updated.

SetupTracing should pass the an empty string as service name other than pingsource.knative-eventing. If passing pingsource.knative-eventing as the service name, an error "host lookup failure: lookup pingsource.knative-eventing on 10.96.0.10:53: no such host" will be reported because there is no service related to PingSource.

After I fixed the issue of SetupTracing in my dev environment and made an update of config-tracing, I could see traces of pingsource from zipkin web UI.

I'm going to create an issue in "knative-dev/pkg" to track the issue of SetupDynamicPublishing. I think the paramters of SetupDynamicPublishing might need to be changed. After that, we can fix the issue of SetupTracing in eventing. SetupDynamicPublishing is called in several places in eventing which might be affected.

[liuchangyan]

I have a PR to fix host lookup failure: lookup pingsource.knative-eventing on 10.96.0.10:53: no such host this bug: https://github.com/knative/eventing/pull/6459