[processor/tailsampling] Include componentID as prefix in metrics 'policy'

[EOjeah]

Description:
Fixing a bug - This change includes the componentID as a dot prefix to the metrics policy dimension when generating metrics for the processor. The change ensures that similarly named policy's in the tail sampling processor that belong to different components also has a unique value in the policy field for the metrics.

Also includes minor refactor change to rename telemetry to telemetryBuilder where applicable (return type == NewTelemetryBuilder)

Resolves: #34099

Link to tracking Issue:

Testing:
Ran the collector locally with make run with the configuration below which uses the tail sampling processor and has metrics exposed in prometheus format. Sending sample zipkin spans to the receiver

receivers:
  zipkin:

processors:
  tail_sampling:
    policies:
      [
          {
            name: test-policy-1,
            type: always_sample
          }
      ]

  tail_sampling/custom_name:
    policies:
      [
          {
            name: test-policy-1,
            type: always_sample
          }
      ]

exporters:
  debug:

service:
  telemetry:
    logs:
    metrics:
  pipelines:
    traces:
      receivers: [zipkin]
      processors: [tail_sampling, tail_sampling/custom_name]
      exporters: [debug]

Curling the metrics endpoint shows the policy name is unique for both tail sampling processors

otelcol_processor_tail_sampling_sampling_decision_latency_bucket{policy="custom_name.test-policy-1",service_instance_id="X",service_name="otelcontribcol",service_version="0.105.0-dev",le="5000"} 1

otelcol_processor_tail_sampling_sampling_decision_latency_bucket{policy="test-policy-1",service_instance_id="X",service_name="otelcontribcol",service_version="0.105.0-dev",le="5000"} 1

Tasks

• Confirm prefix separator as .
• Update change log entry

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.

[EOjeah]

Not urgent but tagging @jpkrohling (currently on holiday) just so it's not closed due to inactivity

[jpkrohling]

There seems to be a lot of unrelated changes in this PR, like the renaming of telemetry to telemetryBuilder. The actual change is quite small and localized, and reviewing it would have been otherwise straightforward.

I have not seen new tests exercising the new code path: can you please add a new test?

[EOjeah]

Reverted the change that renamed telemetry to telemetryBuilder.

In order to receive the processor settings, which contains the component.ID in the newTracesProcessor function, the newTracesProcessor function had to be updated to accept the processor.Settings and not just the processor.Settings.TelemetrySettings

A few of the existing tests use the function and provided the TelemetrySettings, updated them to provide the processor Settings instead

Settings

// Settings is passed to Create* functions in Factory.
type Settings struct {
  // ID returns the ID of the component that will be created.
  ID component.ID

  component.TelemetrySettings

  // BuildInfo can be used by components for informational purposes
  BuildInfo component.BuildInfo
}

Included a test that verifies the policy value in the metrics generated includes the ID as a dot . prefix

[jpkrohling]

The actual change LGTM, just not sure about the reason for renaming the telemetry settings.

[jpkrohling]

Is there a good reason for renaming component.TelemetrySettings from settings to telemetrySettings?

[EOjeah]

It was only to differentiate between the new argument processor.Settings (settings) from initial argument which was processor.Settings.TelemetrySettings (telemetrySettings)

Do i change it to below instead?

func newTracesProcessor(ctx context.Context, processorSettings processor.Settings, ...) (processor.Traces, error) {
  settings := processorSettings.TelemetrySettings
  telemetry, err := metadata.NewTelemetryBuilder(settings)
  if err != nil {
    return nil, err
  }
  ...
}

[jpkrohling]

No, it's okay. This is small enough to not be a problem.

[EOjeah]

added the changelog entry so re-request approval