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feat(config): TracerProvider creation from declarative config#4985

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MikeGoldsmith wants to merge 10 commits intoopen-telemetry:mainfrom
MikeGoldsmith:mike/config-tracer-provider
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feat(config): TracerProvider creation from declarative config#4985
MikeGoldsmith wants to merge 10 commits intoopen-telemetry:mainfrom
MikeGoldsmith:mike/config-tracer-provider

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@MikeGoldsmith MikeGoldsmith commented Mar 16, 2026

Description

Implements create_tracer_provider() and configure_tracer_provider() for the declarative configuration pipeline, as part of the ongoing work tracked in the following PR:

Note

This PR is based on #4979 (Resource & Propagator creation) which must be merged first. The extra commits at the base of this branch will be dropped once that PR lands.

What's included

  • _tracer_provider.py: creates an SDK TracerProvider from declarative config
  • Supports all sampler types: always_on, always_off, trace_id_ratio_based, parent_based (with all 4 delegate samplers)
  • Supports BatchSpanProcessor and SimpleSpanProcessor
  • Supports OTLP HTTP, OTLP gRPC, and Console span exporters
  • Lazy imports for optional OTLP packages with a ConfigurationError if not installed
  • SpanLimits and sampler use OTel spec defaults for absent fields — no env-var leakage
  • configure_tracer_provider(None) is a no-op per spec/Java/JS behavior
  • 32 new tests covering all paths including env-var suppression

Env-var suppression

Python's TracerProvider reads OTEL_TRACES_SAMPLER when sampler=None, and SpanLimits reads OTEL_SPAN_*_LIMIT when fields are None. To match the spec's "what you see is what you get" semantics (and Java SDK behavior), we always pass explicit values — defaulting to spec defaults (e.g. ParentBased(root=ALWAYS_ON), 128 for count limits) rather than falling through to env vars.

Type of change

  • 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?

  • 32 unit tests in tests/_configuration/test_tracer_provider.py
  • Includes explicit tests that env vars (OTEL_TRACES_SAMPLER, OTEL_SPAN_ATTRIBUTE_COUNT_LIMIT) are not read when config is used

Does This PR Require a Contrib Repo Change?

  • Yes.
  • No.

Checklist:

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

Assisted-by: Claude Sonnet 4.6

Implements create_resource() and create_propagator()/configure_propagator()
for the declarative file configuration. Resource creation does not read
OTEL_RESOURCE_ATTRIBUTES or run any detectors (matches Java/JS SDK behavior).
Propagator configuration always calls set_global_textmap to override Python's
default tracecontext+baggage, setting a noop CompositePropagator when no
propagator is configured.

Assisted-by: Claude Sonnet 4.6
Assisted-by: Claude Sonnet 4.6
- _resource.py: refactor _coerce_attribute_value to dispatch table to
  avoid too-many-return-statements; fix short variable names k/v ->
  attr_key/attr_val; fix return type of _sdk_default_attributes to
  dict[str, str] to satisfy pyright
- _propagator.py: rename short variable names e -> exc, p -> propagator
- test_resource.py: move imports to top level; split TestCreateResource
  (25 methods) into three focused classes to satisfy too-many-public-methods
- test_propagator.py: add pylint disable for protected-access

Assisted-by: Claude Sonnet 4.6
- replace _sdk_default_attributes() with _DEFAULT_RESOURCE from resources module
- move _coerce_bool into dispatch tables for both scalar and array bool types,
  fixing a bug where bool_array with string values like "false" would coerce
  incorrectly via plain bool() (non-empty string -> True)
- add test for bool_array with string values to cover the bug

Assisted-by: Claude Sonnet 4.6
Implements create_tracer_provider() and configure_tracer_provider() for
the declarative configuration pipeline (tracking issue open-telemetry#3631 step 5).

Key behaviors:
- Never reads OTEL_TRACES_SAMPLER or OTEL_SPAN_*_LIMIT env vars; absent
  config fields use OTel spec defaults (matching Java SDK behavior)
- Default sampler is ParentBased(root=ALWAYS_ON) per the OTel spec
- SpanLimits absent fields use hardcoded defaults (128) not env vars
- configure_tracer_provider(None) is a no-op per spec/Java/JS behavior
- OTLP exporter fields pass None through so the exporter reads its own
  env vars for unspecified values
- Lazy imports for optional OTLP packages with ConfigurationError on missing
- Supports all 4 ParentBased delegate samplers

Assisted-by: Claude Sonnet 4.6
Assisted-by: Claude Sonnet 4.6
- add # noqa: PLC0415 to lazy OTLP imports (ruff also enforces this)
- move SDK imports to top-level (BatchSpanProcessor, etc.)
- convert test helper methods to @staticmethod to satisfy no-self-use
- add pylint: disable=protected-access for private member access in tests
- fix return type annotation on _create_span_processor

Assisted-by: Claude Sonnet 4.6
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