feat: Extract resource name from unary requests for tracing

[blakeli0]

This PR updates the gapic-generator-java and GAPIC core telemetry layer to extract destination resource names from request payloads via google.api.resource_reference.

Changes:

• Generator Logic: AbstractTransportServiceStubClassComposer was updated to securely parse resource_reference annotations and emit .setResourceNameExtractor(...) logic onto stub settings upon compilation. Added safeguard logic for repeated fields.
• Unary Trace Injection: Engineered GrpcCallSettings, HttpJsonCallSettings, and TracedUnaryCallable to securely intercept requests right before initiating the trace, cloning and stamping the resource value to the active Observability map.
• ApiTracerContext: Added destinationResourceId to ApiTracerContext to propagate upstream context.
• Showcase: Updated existing showcase tests to use IdentityClient instead of EchoClient. Because EchoClient does not have any message that is configured with resource_reference.

This is a first PR for implementing Destination resource names. There will be a follow up PR that extract resource names based on heuristics if resource names are not explicitly configured.

[gemini-code-assist]

Summary of Changes

Hello, 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 significantly enhances the telemetry capabilities within the GAPIC client libraries by introducing automatic extraction of destination resource names from unary request payloads. The changes span the code generation layer, the core GAX library's tracing context, and the underlying callable implementations for both gRPC and HTTP/JSON transports. This ensures that critical resource identification is consistently captured and propagated for improved observability without requiring manual configuration.

Highlights

• Telemetry Enhancement: The gapic-generator-java and GAPIC core telemetry layer now natively extract destination resource names from request payloads using google.api.resource_reference annotations.
• Generator Logic Update: AbstractTransportServiceStubClassComposer was updated to parse resource_reference annotations and emit .setResourceNameExtractor(...) logic onto stub settings during compilation, including safeguards for repeated fields.
• ApiTracerContext Extension: The ApiTracerContext now includes serviceName, urlDomain, urlTemplate, and specifically destinationResourceName to propagate upstream context for improved tracing.
• Core Telemetry Consolidation: Scattered GoldenSignalMetricsTracer variants have been deprecated, standardizing on a uniform metrics tag caching implementation that accepts ApiTracerContext.
• Unary Trace Injection: GrpcCallSettings, HttpJsonCallSettings, and TracedUnaryCallable were engineered to intercept requests before tracing, cloning and stamping the resource value to the active Observability map.
• Bazel Bzlmod Adoption: New MODULE.bazel and MODULE.bazel.lock files were added, indicating a migration towards Bazel's Bzlmod for external dependency management.
• Golden File Regeneration: Integration goldens and unit test goldens were regenerated to reflect the new telemetry logic and resource name extraction.

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[gemini-code-assist]

Code Review

This pull request introduces a new client resource name extractor mechanism across the GAX (Google API eXtensions) libraries to enhance tracing and observability. The changes involve defining a ClientResourceNameExtractor interface, integrating a destinationResourceName field into ApiTracerContext for attribute propagation, and modifying GrpcCallSettings and HttpJsonCallSettings to incorporate this extractor. The TracedUnaryCallable now utilizes this extractor to populate the resource name in the ApiTracerContext. The gapic-generator-java has been updated to automatically generate the necessary code for creating and setting these extractors in gRPC and HTTP JSON client stub classes, based on resource reference annotations in proto files. This is validated through new test cases and updates to numerous golden files across various client libraries, ensuring consistent resource name extraction for tracing purposes. Minor Bazel build system updates are also included.

[diegomarquezp]

Thanks for the PR!

[diegomarquezp]

Can we add an assertion to the ITOtelTracing test to confirm the resource name attribute is being collected in the client?

[blakeli0]

Done. I changed the EchoClient to IdentityClient because EchoClient does not have any message that is configured with resource_reference. The changes in GrpcEchoStub is due to mixins.

[diegomarquezp]

Thank you.

[diegomarquezp]

LGTM. I'll wait for @lqiu96.

[lqiu96]

Generator Logic: AbstractTransportServiceStubClassComposer was updated to securely parse resource_reference annotations and emit .setResourceNameExtractor(...) logic onto stub settings upon compilation. Added safeguard logic for repeated fields.

Two general questions:

1. IIUC, this essentially parses the resource_reference from the request to get the path. I believe it gets the first path from the resource. What if a resource has multiple patterns and a method has multiple additional_bindings? It may be possible that the resource_reference doesn't actually point to the right spot. Granted, I think there are very few (if any at all) where this would occur, but do we want to consider this case (or possibly as a later fix)?
2. Does this impact streaming calls? If so, do we care for now or is the current behavior acceptable?

[sonarqubecloud]

Quality Gate failed for 'gapic-generator-java-root'

Failed conditions
8.2% Duplication on New Code (required ≤ 3%)

See analysis details on SonarQube Cloud

[blakeli0]

I believe it gets the first path from the resource

It gets the first field that has resource_reference, and extracts its value during runtime.

What if a resource has multiple patterns and a method has multiple additional_bindings?

As long as a field is configured with resource_reference, we will use its value regardless of the patterns.

It may be possible that the resource_reference doesn't actually point to the right spot

I think we have validations during generation time to validate the resources are valid?

Does this impact streaming calls? If so, do we care for now or is the current behavior acceptable?

The generation applies to all calls so it does affect streaming calls. The extraction is only done for UnaryCalls currently. It will be done for other streaming calls in the future.

[sonarqubecloud]

Quality Gate failed for 'java_showcase_integration_tests'

Failed conditions
48.7% Coverage on New Code (required ≥ 80%)
10.4% Duplication on New Code (required ≤ 3%)

See analysis details on SonarQube Cloud

[lqiu96]

Taking a step back to make sure that we are on the same page. IIUC, what is is doing is something like this:

RPC

  // Deletes a user, their profile, and all of their authored messages.
  rpc DeleteUser(DeleteUserRequest) returns (google.protobuf.Empty) {
    option (google.api.http) = {
      delete: "/v1beta1/{name=users/*}"
    };
    option (google.api.method_signature) = "name";
  }

Request

message DeleteUserRequest {
  // The resource name of the user to delete.
  string name = 1 [
    (google.api.resource_reference).type = "showcase.googleapis.com/User",
    (google.api.field_behavior) = REQUIRED
  ];
}

It will extract the the resourceId as name = users/user1234 at put that as the Otel attribute. I think this makes sense.

If the resource has multiple patterns, it just extracts the value. So the value inside the request matches with any of the possible additional_bindings and that is fine (if it doesn't match with any then the server would throw an error anyways, same behavior it does it there is only one pattern anways).

Ok, I think that makes sense. LGTM.

[lqiu96]

If possible, maybe a small showcase test in a follow up PR?

[blakeli0]

If possible, maybe a small showcase test in a follow up PR?

ITOtelTracing has been updated already.