Allow for declarative exclusion of Telemetry spans being generated from HelidonTelemetryClientFilter

[jvissers]

Environment Details

• Helidon Version: 4.1.4
• Helidon MP
• OpenJDK 64-Bit Server VM (build 23+37-2369, mixed mode, sharing)
• OS: Ubuntu 24.04.1 LTS

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Feature Request

We have a number of Microprofile Healthchecks, that of which leverage the REST client to check prerequisites for OCI ObjectStorage access. Because of the HelidonTelemetryClientFilter this now generates spans that are unwanted, and result in a considerable amount of noise. We are raising this feature request to ask for a mechanism that allows us to declaratively specify some exclusion(s) criteria that avoids creating these unwanted spans.

Workaround

The workaround suggested, in our case where we use OTEL, is to create a custom SpanProcessor that would then pick up information from a (Helidon) context to shortcircuit the span. From the calling code (i.e., a Health check component) the idea would be then to set up that piece of information and make it available through runInContext, for the custom SpanProcessor to use.

[jvissers]

For completeness; the suggested workaround doesn't actually stop the noisy traces. That is something that currently we simply cannot control, as the trace/span is created from within the HelidonTelemetryClientFilter. So ultimately we should consider rewording this issue, to indicate that really we want to avoid noisy traces from ending up being emitted.