feat(config): sampler plugin loading via entry points for declarative config#5095
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MikeGoldsmith wants to merge 8 commits intoopen-telemetry:mainfrom
Open
feat(config): sampler plugin loading via entry points for declarative config#5095MikeGoldsmith wants to merge 8 commits intoopen-telemetry:mainfrom
MikeGoldsmith wants to merge 8 commits intoopen-telemetry:mainfrom
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Extracts a generic `load_entry_point(group, name)` helper into `_common` so that resource detector, exporter, propagator, and sampler plugin loading in declarative file config can all use the same entry point lookup pattern rather than duplicating it. Refactors `_propagator.py` to use the new util, removing its inline entry point lookup. Assisted-by: Claude Sonnet 4.6
Assisted-by: Claude Sonnet 4.6
Extends _create_sampler() to accept raw dicts (from the YAML path) in
addition to typed dataclasses (from the direct API path). Unknown sampler
names fall back to load_entry_point("opentelemetry_sampler", name),
matching the spec's PluginComponentProvider mechanism and Java SDK
behaviour.
_create_parent_based_sampler() gets the same dict-path treatment so
custom samplers can be used as delegate samplers inside parent_based.
Assisted-by: Claude Sonnet 4.6
Sampler and ParentBasedSampler are changed from @DataClass to TypeAlias = dict[str, Any] in models.py. The generated dataclass representation dropped unknown keys, making plugin sampler names unrecoverable before reaching the factory. The dict type preserves the raw YAML key, which is the plugin name. _create_sampler() now has a single code path: extract the single key as the sampler name, look it up in _SAMPLER_REGISTRY (always_on, always_off, trace_id_ratio_based, parent_based), and fall back to load_entry_point("opentelemetry_sampler", name) for unknown names. This matches the spec's PluginComponentProvider mechanism. Assisted-by: Claude Sonnet 4.6
This was referenced Apr 20, 2026
Python dataclasses don't enforce types at runtime, so factory functions can accept raw dicts without changing the generated models. This keeps models.py identical to the codegen output. Assisted-by: Claude Opus 4.6 (1M context)
Use typed SamplerConfig and ParentBasedSamplerConfig with additional_properties from the @_additional_properties decorator instead of raw dict iteration. Known sampler types are checked via typed fields. Unknown plugin names from additional_properties are loaded via the opentelemetry_sampler entry point group. Assisted-by: Claude Opus 4.6
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Description
Extends sampler support in declarative file configuration to handle custom (plugin) samplers, matching the spec's PluginComponentProvider mechanism.
Depends on #5131 (
additional_propertiessupport for generated models).Solution
_create_sampler()checks typed fields on theSamplerdataclass for known types (always_on,always_off,trace_id_ratio_based,parent_based), then falls back toadditional_propertiesfor unknown plugin names loaded viaload_entry_point("opentelemetry_sampler", name)._create_parent_based_sampler()uses typedParentBasedSamplerfields for delegate samplers.Custom sampler example
Closes #5071