opentelemetry-sdk: Implement tracer configurator #4861

xrmx · 2025-12-17T11:40:32Z

Description

Implement part of the tracing SDK spec to configure the tracers https://opentelemetry.io/docs/specs/otel/trace/sdk/#configuration

At the moment this adds helper in order to enable or disable a tracer after it has been created.

The spec in is development so attributes, helpers and classes are prefixed with underscore.

TODO:

hook into sdk configuration
add an example rule based configurator so that we can express the tracer filter by name there

Type of change

Please delete options that are not relevant.

Bug fix (non-breaking change which fixes an issue)
New feature (non-breaking change which adds functionality)
Breaking change (fix or feature that would cause existing functionality to not work as expected)
This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

tox

Does This PR Require a Contrib Repo Change?

Yes. - Link to PR:
No.

Checklist:

Followed the style guidelines of this project
Changelogs have been updated
Unit tests have been added
Documentation has been updated

aabmass · 2025-12-18T17:21:24Z

opentelemetry-sdk/src/opentelemetry/sdk/trace/__init__.py

        id_generator: Optional[IdGenerator] = None,
        span_limits: Optional[SpanLimits] = None,
+        *,
+        _tracer_configurator: Optional[_TracerConfiguratorT] = None,


This was the java thing I was mentioning: https://github.com/open-telemetry/opentelemetry-java/tree/main/api/incubator

I agree it might be overkill for this feature though.

Yeah, I'm not sure how this maps into Python. The implementation I've added here with adding a new kwarg prefixed with the underscore is more or less the same it would be the concrete implementation when using overload to provide the one with only stable parameters.

xrmx · 2025-12-19T13:19:36Z

opentelemetry-sdk/src/opentelemetry/sdk/trace/__init__.py



+_TracerConfiguratorT = Callable[[InstrumentationScope], _TracerConfig]
+_TracerConfiguratorRulesPredicateT = Callable[


I guess a callable is not very declarative config friendly

Changed the interface to something that matches the config schema
https://github.com/open-telemetry/opentelemetry-configuration/blob/e4d2fdb07539ada5d1d5ab929f71a45705792fa3/schema/tracer_provider.yaml#L20

xrmx · 2025-12-24T16:52:28Z

opentelemetry-sdk/src/opentelemetry/sdk/_configuration/__init__.py

    return environ.get(OTEL_PYTHON_ID_GENERATOR, _DEFAULT_ID_GENERATOR)


+def _get_tracer_configurator() -> str | None:


I've added the configuration via env var to match what we are doing with the others TraceProvider parameters, since this is in development I can drop it. For my use case I can just use _OTelSDKConfigurator._configure.

jack-berg · 2025-12-31T17:26:15Z

opentelemetry-sdk/src/opentelemetry/sdk/trace/__init__.py

        set_status_on_exception: bool = True,
    ) -> trace_api.Span:
+        if not self._is_enabled:
+            return INVALID_SPAN


The key behavior of tracer configurator is:

If a Tracer is disabled, it MUST behave equivalently to a No-op Tracer.".

(from the spec)

Where the behavior of a noop tracer is:

However, there is one important exception to this general rule, and that is related to propagation of a SpanContext: The API MUST return a non-recording Span with the SpanContext in the parent Context (whether explicitly given or implicit current). If the Span in the parent Context is already non-recording, it SHOULD be returned directly without instantiating a new Span. If the parent Context contains no Span, an empty non-recording Span MUST be returned instead (i.e., having a SpanContext with all-zero Span and Trace IDs, empty Tracestate, and unsampled TraceFlags). This means that a SpanContext that has been provided by a configured Propagator will be propagated through to any child span and ultimately also Inject, but that no new SpanContexts will be created.

Does INVALID_SPAN here follow this behavior? In the java implementation, we use the noop tracer when a tracer is disabled, which returns a non-recording span to propagator the span context here.

The NoOpTracer in Python has the very same behavior of returning INVALID_SPAN, that is a NonRecordingSpan:

INVALID_SPAN = NonRecordingSpan(INVALID_SPAN_CONTEXT)

That may not match what the spec says though. Thanks for the review.

Is the point here that the INVALID_SPAN from a disabled tracer will break trace propagation/parenting for any spans created under the disabled tracer's span?

Yes. Well, that's what I assume without looking deeply at the python code.

Suppose you have a trace:

-> (root) span A, from scope A
|-> span B, from scope B
|-> span C, from scope C

If I disable scope B, then I should see:

-> (root) span A, from scope A
|-> span C, from scope C

But unless I'm misunderstanding, in python the behavior is something like:

-> (root) span A, from scope A
-> span C, from scope C

Where span C's parent is an invalid span, and so results in a broken trace.

Please correct me if I'm misunderstanding.

Updated the NoOpTracer and the not enabled sdk tracer to not return an invalid span but a NonRecordingSpan with the proper context. Could use more tests I think.

Missed the part of reusing the very same NonRecordingSpan, updated and added more tests.

opentelemetry-api/src/opentelemetry/trace/__init__.py

Implement part of the tracing SDK spec to configure the tracers https://opentelemetry.io/docs/specs/otel/trace/sdk/#configuration At the moment this adds helper in order to enable or disable a tracer after it has been created. The spec in is development so attributes, helpers and classes are prefixed with underscore. TODO: hook into sdk configuration

…eclarative config schema

herin049 · 2026-01-21T19:43:34Z

opentelemetry-sdk/src/opentelemetry/sdk/trace/__init__.py

+]
+
+
+def _tracer_name_matches_glob(


Given that we'll want to add configurations for meters and loggers maybe we can make this more general and move it somewhere else to just be:

def _scope_name_matches_glob( glob_pattern: str, ) -> _InstrumentationScopePredicateT: def inner(scope: InstrumentationScope) -> bool: return fnmatch.fnmatch(scope.name, glob_pattern) return inner

xrmx requested a review from a team as a code owner December 17, 2025 11:40

aabmass reviewed Dec 18, 2025

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xrmx commented Dec 19, 2025

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xrmx added this to @xrmx's Python PR digest Dec 24, 2025

xrmx moved this to Ready for review in @xrmx's Python PR digest Dec 24, 2025

xrmx commented Dec 24, 2025

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jack-berg reviewed Dec 31, 2025

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aabmass mentioned this pull request Jan 9, 2026

[Feat]: Support disabling A2A OTEL Instrumentation a2aproject/a2a-python#604

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xrmx requested review from aabmass and jack-berg January 16, 2026 10:52

herin049 approved these changes Jan 19, 2026

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mariojonke reviewed Jan 21, 2026

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opentelemetry-api/src/opentelemetry/trace/__init__.py Outdated Show resolved Hide resolved

xrmx added 14 commits January 22, 2026 11:07

Please lint

6b2d695

Add rule based tracer configurator

2622c0c

Assume rule based tracer configurator in helpers

82f2d05

Fix lint

f2d8841

Add changelog

a17f947

hook into auto-instrumentation

5998b32

Don't return invalid spans from NoOpTracer

456a2ff

Adapt after nooptracer behaviour change

c80b2d8

Please lint

b86b322

Rework _RuleBasedTracerConfigurator interface to match the one from d…

774abd2

…eclarative config schema

More correct nooptracer and more test coverage

3a51dee

Ignore typechecking in validation test

6bf38a7

Handle invalid span context more gracefully

9726fec

xrmx force-pushed the experimental-tracer-configurator branch from b0e8ccb to 9726fec Compare January 22, 2026 10:08

Return invalid span in case span context is invalid

4714f5e

herin049 reviewed Jan 22, 2026

View reviewed changes



		_TracerConfiguratorT = Callable[[InstrumentationScope], _TracerConfig]
		_TracerConfiguratorRulesPredicateT = Callable[

		return environ.get(OTEL_PYTHON_ID_GENERATOR, _DEFAULT_ID_GENERATOR)


		def _get_tracer_configurator() -> str \| None:

opentelemetry-sdk: Implement tracer configurator #4861

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xrmx commented Dec 17, 2025 •

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