[OpenTelemetry] Model changes to allow OpenTelemetry context propagation by stankiewicz · Pull Request #36962 · apache/beam

stankiewicz · 2025-12-02T13:46:44Z

Changes:

dependencies definitions to otel
WindowedValue interface change to expose context for propagation - context is not read by user
changes are behind external_metadata experiment

Next PRs:

propagation to windmill sink
reading from windmill reader
enabling default otel implementation for dataflow runner (v1 with propagation, v2 no propagation yet)

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stankiewicz · 2025-12-02T13:47:06Z

R: @sjvanrossum

gemini-code-assist · 2025-12-02T13:47:13Z

Summary of Changes

Hello @stankiewicz, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request lays the foundational groundwork for integrating OpenTelemetry context propagation within Apache Beam. It involves updating OpenTelemetry dependencies, extending the internal data model (beam_fn_api.proto and WindowedValue interface) to carry trace context information, and implementing the necessary serialization/deserialization logic. These changes are part of an ongoing effort to enhance observability by enabling end-to-end distributed tracing across Beam pipelines, currently under an experimental flag.

Highlights

OpenTelemetry Dependency Updates: Updated and added several OpenTelemetry dependencies in BeamModulePlugin.groovy and various build.gradle files to support OpenTelemetry context propagation.
Protocol Buffer Extension for Trace Context: Modified beam_fn_api.proto to include traceparent and tracestate fields within the ElementMetadata message, enabling the serialization of W3C Trace Context.
WindowedValue Interface Enhancement: Extended the WindowedValue interface and its implementations to include a getContext() method, allowing the OpenTelemetry Context to be associated with and propagated alongside data elements.
OpenTelemetry Context Serialization: Introduced OpenTelemetryContextSerializer to handle the encoding and decoding of OpenTelemetry Context objects into and from the ElementMetadata of WindowedValue using the W3C Trace Context Propagator.
Experimental Feature: These changes are implemented behind an external_metadata experiment flag, indicating an incremental rollout and testing approach.

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github-actions · 2025-12-02T13:48:48Z

Stopping reviewer notifications for this pull request: review requested by someone other than the bot, ceding control. If you'd like to restart, comment assign set of reviewers

stankiewicz · 2025-12-02T15:15:24Z

/gemini review

gemini-code-assist

Code Review

The pull request effectively integrates OpenTelemetry context propagation into Apache Beam's core data structures and serialization mechanisms. This foundational change is well-implemented across various files, ensuring the Context is carried alongside WindowedValue elements. Key aspects include updating dependencies, extending the protocol buffer schema for traceparent and tracestate, modifying core WindowedValue interfaces and implementations to include the Context, and implementing robust serialization/deserialization logic via OpenTelemetryContextSerializer. The addition of a test case in WindowedValueTest.java validates the new functionality. The use of null for getContext() in specific overrides is consistent with the stated scope that the context is not yet consumed by users. Overall, this is a solid and necessary step towards comprehensive OpenTelemetry integration.

sdks/java/core/src/main/java/org/apache/beam/sdk/values/WindowedValues.java

...ud-platform-core/src/test/java/org/apache/beam/sdk/extensions/gcp/GcpCoreApiSurfaceTest.java

kennknowles · 2025-12-08T16:10:13Z

buildSrc/src/main/groovy/org/apache/beam/gradle/BeamModulePlugin.groovy

-        opentelemetry_api                           : "io.opentelemetry:opentelemetry-api", // google_cloud_platform_libraries_bom sets version
+        opentelemetry_api                           : "io.opentelemetry:opentelemetry-api:$opentelemetry_version",
        opentelemetry_bom                           : "io.opentelemetry:opentelemetry-bom-alpha:$opentelemetry_version-alpha", // alpha required by extensions
+        opentelemetry_context                       : "io.opentelemetry:opentelemetry-context:$opentelemetry_version",


Will this change conflict with the GCP BOM? @suztomo do you think this is fine? We might just need to check them together manually.

...e-cloud-dataflow-java/src/main/java/org/apache/beam/runners/dataflow/BatchViewOverrides.java

sdks/java/core/src/main/java/org/apache/beam/sdk/values/WindowedValues.java

kennknowles · 2025-12-08T16:25:58Z

sdks/java/core/src/main/java/org/apache/beam/sdk/values/WindowedValues.java

+    }
+
+    public static Context read(BeamFnApi.Elements.ElementMetadata from) {
+      return W3CTraceContextPropagator.getInstance().extract(Context.root(), from, GETTER);


OK... this way of doing things matches https://opentelemetry.io/docs/specs/otel/context/api-propagators/

But it does seem like a complicated way of doing the equivalent of

W3TraceContextPropagator.getInstance().setTracestate(elementMetadata.getTracestate()); W3TraceContextPropagator.getInstance().setTraceparent(elementMetadata.getTraceparent());

and

elementMetadataBuilder.setTracestate(W3TraceContextPropagator.getInstance().getTracestate()); elementMetadataBuilder.setTraceparent(W3TraceContextPropagator.getInstance().getTraceparent());

Other nit: did we not agree that the ElementMetadata object should be only implementation detail? This class and everything should be private since it is just for encoding/decoding utility. But potentially also you want to do the SETTER on an Builder and the GETTER on a WindowedValue. If it is implementation detail, hidden, then I don't care that much, but if it is public then we have to be careful about what classes we use.

Yes, but I don't want to reimplement W3CTraceContextPropagator to have getTraceState /getTraceParent methods.

On nits - ValueInSingleWindow is not implementing WindowedValue interface now. Once it will, I can improve that.
Setter has builder already.

sdks/java/core/src/main/java/org/apache/beam/sdk/values/WindowedValues.java

buildSrc/src/main/groovy/org/apache/beam/gradle/BeamModulePlugin.groovy

sdks/java/core/src/main/java/org/apache/beam/sdk/values/WindowedValues.java

sdks/java/core/src/main/java/org/apache/beam/sdk/values/ValueInSingleWindow.java

sdks/java/core/src/main/java/org/apache/beam/sdk/values/WindowedValue.java

sdks/java/core/src/main/java/org/apache/beam/sdk/values/WindowedValues.java

github-actions · 2026-02-27T12:48:16Z

This pull request has been marked as stale due to 60 days of inactivity. It will be closed in 1 week if no further activity occurs. If you think that’s incorrect or this pull request requires a review, please simply write any comment. If closed, you can revive the PR at any time and @mention a reviewer or discuss it on the dev@beam.apache.org list. Thank you for your contributions.

stankiewicz · 2026-03-02T11:59:07Z

need to resolve conflicts and it will be ready soon.

stankiewicz · 2026-03-02T15:04:38Z

Run Java_IOs_Direct PreCommit

stankiewicz · 2026-03-02T15:05:15Z

Run Java PreCommit

sdks/java/core/src/main/java/org/apache/beam/sdk/values/WindowedValue.java

stankiewicz · 2026-03-11T12:02:36Z

Run Java PreCommit

sjvanrossum

Minor feedback, LGTM overall.

buildSrc/src/main/groovy/org/apache/beam/gradle/BeamModulePlugin.groovy

sjvanrossum · 2026-03-11T13:20:55Z

buildSrc/src/main/groovy/org/apache/beam/gradle/BeamModulePlugin.groovy

+        opentelemetry_api                           : "io.opentelemetry:opentelemetry-api:$opentelemetry_sdk_version",
+        opentelemetry_bom                           : "io.opentelemetry:opentelemetry-bom-alpha:$opentelemetry_sdk_version-alpha", // alpha required by extensions
+        opentelemetry_context                       : "io.opentelemetry:opentelemetry-context:$opentelemetry_sdk_version",
+        opentelemetry_gcp_auth                      : "io.opentelemetry.contrib:opentelemetry-gcp-auth-extension:$opentelemetry_contrib_version-alpha",
+        opentelemetry_sdk                           : "io.opentelemetry:opentelemetry-sdk:$opentelemetry_sdk_version",
+        opentelemetry_exporter_otlp                 : "io.opentelemetry:opentelemetry-exporter-otlp:$opentelemetry_sdk_version",
+        opentelemetry_extension_autoconfigure       : "io.opentelemetry:opentelemetry-sdk-extension-autoconfigure:$opentelemetry_sdk_version",


GCP BOM sets OpenTelemetry SDK version iirc:

Suggested change

opentelemetry_api : "io.opentelemetry:opentelemetry-api:$opentelemetry_sdk_version",

opentelemetry_bom : "io.opentelemetry:opentelemetry-bom-alpha:$opentelemetry_sdk_version-alpha", // alpha required by extensions

opentelemetry_context : "io.opentelemetry:opentelemetry-context:$opentelemetry_sdk_version",

opentelemetry_gcp_auth : "io.opentelemetry.contrib:opentelemetry-gcp-auth-extension:$opentelemetry_contrib_version-alpha",

opentelemetry_sdk : "io.opentelemetry:opentelemetry-sdk:$opentelemetry_sdk_version",

opentelemetry_exporter_otlp : "io.opentelemetry:opentelemetry-exporter-otlp:$opentelemetry_sdk_version",

opentelemetry_extension_autoconfigure : "io.opentelemetry:opentelemetry-sdk-extension-autoconfigure:$opentelemetry_sdk_version",

opentelemetry_api : "io.opentelemetry:opentelemetry-api", // google_cloud_platform_libraries_bom sets version

opentelemetry_bom : "io.opentelemetry:opentelemetry-bom-alpha:$opentelemetry_sdk_version-alpha", // alpha required by extensions

opentelemetry_context : "io.opentelemetry:opentelemetry-context", // google_cloud_platform_libraries_bom sets version

opentelemetry_gcp_auth : "io.opentelemetry.contrib:opentelemetry-gcp-auth-extension:$opentelemetry_contrib_version-alpha",

opentelemetry_sdk : "io.opentelemetry:opentelemetry-sdk", // google_cloud_platform_libraries_bom sets version

opentelemetry_exporter_otlp : "io.opentelemetry:opentelemetry-exporter-otlp", // google_cloud_platform_libraries_bom sets version

opentelemetry_extension_autoconfigure : "io.opentelemetry:opentelemetry-sdk-extension-autoconfigure", // google_cloud_platform_libraries_bom sets version

sjvanrossum · 2026-03-11T13:31:12Z

sdks/java/core/src/main/java/org/apache/beam/sdk/values/ValueInSingleWindow.java

      BoundedWindow window = windowCoder.decode(inStream);
      PaneInfo paneInfo = PaneInfo.PaneInfoCoder.INSTANCE.decode(inStream);
      CausedByDrain causedByDrain = CausedByDrain.NORMAL;
+      io.opentelemetry.context.@Nullable Context openTelemetryContext = null;


Suggested change

io.opentelemetry.context.@Nullable Context openTelemetryContext = null;

@Nullable io.opentelemetry.context.Context openTelemetryContext = null;

it's valid place for this annotation. It looks strange.

As long as Spotless approves it's fine with me, but it seemed unconventional.
Fun party trick though, I didn't know this was syntactically allowed until I saw it pop up in this PR. 😄

It looks even weirder when it is an inner class (OuterClass.@Nullable InnerClass). Not only is it conventional, it is required. (there is no other valid syntax for this)

sdks/java/core/src/main/java/org/apache/beam/sdk/values/WindowedValues.java

buildSrc/src/main/groovy/org/apache/beam/gradle/BeamModulePlugin.groovy

kennknowles · 2026-03-24T15:09:32Z

sdks/java/core/src/main/java/org/apache/beam/sdk/values/OpenTelemetryContextPropagator.java

+
+class OpenTelemetryContextPropagator {
+
+  private static final TextMapSetter<BeamFnApi.Elements.ElementMetadata.Builder> SETTER =


I feel like errorprone is going to tell you to make this a static method and use a method reference.

it doesn't because TextMapSetter is custom interface. I will keep it as is, as Getter is not a lambda.

kennknowles · 2026-03-24T15:09:41Z

sdks/java/core/src/main/java/org/apache/beam/sdk/values/OpenTelemetryContextPropagator.java

+        }
+      };
+
+  private static final TextMapGetter<BeamFnApi.Elements.ElementMetadata> GETTER =


sdks/java/container/license_scripts/dep_urls_java.yaml

sdks/java/core/src/main/java/org/apache/beam/sdk/values/ValueInSingleWindow.java

kennknowles · 2026-03-24T15:11:46Z

sdks/java/core/src/main/java/org/apache/beam/sdk/values/ValueInSingleWindow.java

      BoundedWindow window = windowCoder.decode(inStream);
      PaneInfo paneInfo = PaneInfo.PaneInfoCoder.INSTANCE.decode(inStream);
      CausedByDrain causedByDrain = CausedByDrain.NORMAL;
+      io.opentelemetry.context.@Nullable Context openTelemetryContext = null;


It looks even weirder when it is an inner class (OuterClass.@Nullable InnerClass). Not only is it conventional, it is required. (there is no other valid syntax for this)

sdks/java/core/src/main/java/org/apache/beam/sdk/values/WindowedValue.java

spotless. rename fields, cleanup groovy spotless

stankiewicz · 2026-03-25T15:47:57Z

Run Java PreCommit

stankiewicz · 2026-03-25T15:48:13Z

Run Java_GCP_IO_Direct PreCommit

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stankiewicz changed the title ~~[OpenTelemetry] Model changes to allow OpenTelemtry context propagation~~ [OpenTelemetry] Model changes to allow OpenTelemetry context propagation Mar 12, 2026

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bump opentelemetry version

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Model changes to allow OpenTelemetry context propagation

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	io.opentelemetry.context.@Nullable Context openTelemetryContext = null;
	@Nullable io.opentelemetry.context.Context openTelemetryContext = null;


		class OpenTelemetryContextPropagator {

		private static final TextMapSetter<BeamFnApi.Elements.ElementMetadata.Builder> SETTER =

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stankiewicz commented Dec 2, 2025 •

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