feat(configuration): add sampler parsing by MikeGoldsmith · Pull Request #6409 · open-telemetry/opentelemetry-js

MikeGoldsmith · 2026-02-13T15:11:21Z

Which problem is this PR solving?

RC3 spec requires sampler configuration via YAML files and environment variables. Currently missing:

Type models for probability/development and composite/development samplers
YAML sampler parsing in FileConfigFactory
Environment variable sampler parsing (OTEL_TRACES_SAMPLER, OTEL_TRACES_SAMPLER_ARG)

Note: jaeger_remote/development is not included as it is an SDK extension plugin (per the spec's isSdkExtensionPlugin: true annotation on the Sampler type) and is expected to be provided via a third-party extension rather than implemented natively. This is consistent with the Java SDK's approach.

Short description of the changes

Type Models (tracerProviderModel.ts):

Added ExperimentalProbabilitySampler interface (matching spec name)
Added ExperimentalComposableSampler, ExperimentalComposableRuleBasedSampler, ExperimentalComposableRuleBasedSamplerRule, ExperimentalComposableParentThresholdSampler, ExperimentalComposableProbabilitySampler interfaces
Extended Sampler union with probability/development and composite/development

YAML Parsing (FileConfigFactory.ts):

Added parseSampler() function supporting all sampler types
Added parseComposableSampler() helper for ExperimentalComposableSampler types
Recursive parsing for nested samplers (parent_based.root, rule-based rules, etc.)
Integrated into setTracerProvider()

Environment Variable Parsing (EnvironmentConfigFactory.ts):

Added setSampler() function (called from within setTracerProvider()) supporting:
- always_on, always_off, traceidratio
- parentbased_always_on, parentbased_always_off, parentbased_traceidratio
Parses OTEL_TRACES_SAMPLER_ARG for ratio values

Tests:

Env var sampler tests: always_on, always_off, traceidratio, parentbased_always_on, parentbased_always_off, parentbased_traceidratio, unknown sampler warning
YAML fixture tests: samplers.yaml (parent_based with probability/development), composite-sampler-array.yaml (rule_based with multiple rules), composite-sampler-rulebased-full.yaml (rule_based with attribute matching)

Type of change

New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Unit tests for env var sampler parsing (always_on, always_off, traceidratio, parentbased variants)
Integration tests for YAML sampler parsing (basic, composite rule_based)
Existing kitchen-sink.yaml includes complex sampler configurations

Checklist:

Followed the style guidelines of this project
Unit tests have been added
Documentation has been updated (CHANGELOG)

- Add type models: ProbabilitySampler, CompositeSampler, RuleBasedSampler - Implement YAML sampler parsing in FileConfigFactory.parseSampler() - Implement env var parsing (OTEL_TRACES_SAMPLER, OTEL_TRACES_SAMPLER_ARG) - Add tests for always_on, always_off, traceidratio, parentbased samplers - Support probability/development and composite/development sampler types Fixes open-telemetry#6290

codecov · 2026-02-13T15:14:43Z

Codecov Report

❌ Patch coverage is 95.04950% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 95.74%. Comparing base (2d361ec) to head (a1ba584).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...al/packages/configuration/src/FileConfigFactory.ts	93.05%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6409      +/-   ##
==========================================
- Coverage   95.74%   95.74%   -0.01%     
==========================================
  Files         364      364              
  Lines       11871    11972     +101     
  Branches     2789     2828      +39     
==========================================
+ Hits        11366    11462      +96     
- Misses        505      510       +5

Files with missing lines	Coverage Δ
...ages/configuration/src/EnvironmentConfigFactory.ts	`99.56% <100.00%> (+0.02%)`	⬆️
...es/configuration/src/models/tracerProviderModel.ts	`100.00% <ø> (ø)`
...al/packages/configuration/src/FileConfigFactory.ts	`97.12% <93.05%> (-0.43%)`	⬇️

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- Convert null values to undefined for always_on/always_off samplers - Ensures consistent behavior with existing defaults - YAML 'always_on:' (no value) → undefined, matching initializeDefaultTracerProviderConfiguration() Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

…o mike/parse-samplers

- Add probability sampler type (non-development) - Make CompositeSampler.samplers optional - Expand RuleBasedSamplerRule with full spec fields - Recursively parse samplers in rule_based rules - Update kitchen-sink test expectations

- Add unknown sampler type warning test - Add parentbased_always_off env var test - Add composite sampler with samplers array test - Add composite sampler with rule_based full features test - Coverage: EnvironmentConfigFactory 98.89%, FileConfigFactory 99.82%

…o mike/parse-samplers

MikeGoldsmith · 2026-03-02T14:28:07Z

Thank you for the review @maryliag and sorry for the delay getting back to you sooner. I'll work through your feedback and get back to you ASAP.

…o mike/parse-samplers

maryliag

thank you for the changes, just a small nit

Assisted-by: Claude Sonnet 4.6

…o mike/parse-samplers

…ILE env var Upstream main renamed OTEL_EXPERIMENTAL_CONFIG_FILE to OTEL_CONFIG_FILE in open-telemetry#6486, but the new sampler parsing tests still referenced the old name. Assisted-by: Claude Sonnet 4.6

…o mike/parse-samplers

MikeGoldsmith requested a review from a team as a code owner February 13, 2026 15:11

update changelog

09143b0

MikeGoldsmith and others added 6 commits February 13, 2026 16:33

Merge branch 'main' of github.com:open-telemetry/opentelemetry-js int…

785ca08

…o mike/parse-samplers

fix(configuration): enhance composite sampler parsing

48c5c8d

- Add probability sampler type (non-development) - Make CompositeSampler.samplers optional - Expand RuleBasedSamplerRule with full spec fields - Recursively parse samplers in rule_based rules - Update kitchen-sink test expectations

Merge branch 'main' of github.com:open-telemetry/opentelemetry-js int…

1ca6a09

…o mike/parse-samplers

run linter

11956e5

maryliag reviewed Mar 2, 2026

View reviewed changes

MikeGoldsmith added 2 commits March 2, 2026 16:00

address review feedback on sampler parsing

5ba3faf

Merge branch 'main' of github.com:open-telemetry/opentelemetry-js int…

8e7708d

…o mike/parse-samplers

maryliag reviewed Mar 3, 2026

View reviewed changes

Comment thread experimental/packages/configuration/src/FileConfigFactory.ts

Comment thread experimental/packages/configuration/src/FileConfigFactory.ts

maryliag approved these changes Mar 3, 2026

View reviewed changes

merge upstream/main into mike/parse-samplers

f8e2b32

Assisted-by: Claude Sonnet 4.6

trentm reviewed Mar 9, 2026

View reviewed changes

Comment thread experimental/CHANGELOG.md Outdated

MikeGoldsmith added 2 commits March 10, 2026 08:40

move changelog entry to unreleased

7943dc1

Merge branch 'main' of github.com:open-telemetry/opentelemetry-js int…

a629374

…o mike/parse-samplers

trentm added this pull request to the merge queue Mar 10, 2026

github-merge-queue Bot removed this pull request from the merge queue due to failed status checks Mar 10, 2026

MikeGoldsmith added 3 commits March 10, 2026 17:04

Merge branch 'main' of github.com:open-telemetry/opentelemetry-js int…

236c4c3

…o mike/parse-samplers

fix(configuration): update sampler tests to use renamed OTEL_CONFIG_F…

acb6fc3

…ILE env var Upstream main renamed OTEL_EXPERIMENTAL_CONFIG_FILE to OTEL_CONFIG_FILE in open-telemetry#6486, but the new sampler parsing tests still referenced the old name. Assisted-by: Claude Sonnet 4.6

Merge branch 'main' of github.com:open-telemetry/opentelemetry-js int…

a1ba584

…o mike/parse-samplers

maryliag added this pull request to the merge queue Mar 13, 2026

Merged via the queue into open-telemetry:main with commit 425bbfe Mar 13, 2026
27 checks passed

MikeGoldsmith deleted the mike/parse-samplers branch March 16, 2026 18:07

otelbot-js Bot mentioned this pull request Mar 20, 2026

chore: prepare next release #6510

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feat(configuration): add sampler parsing#6409

feat(configuration): add sampler parsing#6409
maryliag merged 16 commits intoopen-telemetry:mainfrom
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MikeGoldsmith commented Feb 13, 2026 •

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MikeGoldsmith commented Mar 2, 2026

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MikeGoldsmith commented Feb 13, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Which problem is this PR solving?

Short description of the changes

Type of change

How Has This Been Tested?

Checklist:

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MikeGoldsmith commented Mar 2, 2026

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MikeGoldsmith commented Feb 13, 2026 •

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