feat: use DD_SERVICE for inferred spans when integration service names are removed (#814)

When DD_TRACE_REMOVE_INTEGRATION_SERVICE_NAMES_ENABLED=true and DD_SERVICE is
set, inferred (synthetic) event-source spans use the base service name instead
of the AWS resource/instance representation. This gives users a single setting
to consolidate every trigger span onto the function's service, rather than one
DD_SERVICE_MAPPING entry per trigger type per function.

An explicit DD_SERVICE_MAPPING entry still takes precedence, and default
behavior is unchanged, so existing integration snapshots are unaffected.

Mirrors the resolution order in datadog-lambda-python.

Author: zarirhamza

src/trace/span-inferrer.spec.ts

@@ -325,6 +325,89 @@ describe("SpanInferrer", () => {
     });
   });
 
+  describe("when DD_TRACE_REMOVE_INTEGRATION_SERVICE_NAMES_ENABLED is set to 'true'", () => {
+    beforeEach(() => {
+      process.env.DD_TRACE_REMOVE_INTEGRATION_SERVICE_NAMES_ENABLED = "true";
+    });
+
+    it("uses DD_SERVICE for SNS events", () => {
+      const inferrer = new SpanInferrer(mockWrapper as unknown as TracerWrapper);
+      inferrer.createInferredSpan(snsEvent, {} as any, {} as SpanContext);
+      expect(getStartSpanServiceTag(1)).toBe("mock-lambda-service");
+    });
+
+    it("uses DD_SERVICE for SQS events", () => {
+      const inferrer = new SpanInferrer(mockWrapper as unknown as TracerWrapper);
+      inferrer.createInferredSpan(sqsEvent, {} as any, {} as SpanContext);
+      expect(getStartSpanServiceTag(1)).toBe("mock-lambda-service");
+    });
+
+    it("uses DD_SERVICE for DDB events", () => {
+      const inferrer = new SpanInferrer(mockWrapper as unknown as TracerWrapper);
+      inferrer.createInferredSpan(ddbEvent, {} as any, {} as SpanContext);
+      expect(getStartSpanServiceTag(1)).toBe("mock-lambda-service");
+    });
+
+    it("uses DD_SERVICE for Kinesis events", () => {
+      const inferrer = new SpanInferrer(mockWrapper as unknown as TracerWrapper);
+      inferrer.createInferredSpan(kinesisEvent, {} as any, {} as SpanContext);
+      expect(getStartSpanServiceTag(1)).toBe("mock-lambda-service");
+    });
+
+    it("uses DD_SERVICE for EventBridge events", () => {
+      const inferrer = new SpanInferrer(mockWrapper as unknown as TracerWrapper);
+      inferrer.createInferredSpan(eventBridgeEvent, {} as any, {} as SpanContext);
+      expect(getStartSpanServiceTag(1)).toBe("mock-lambda-service");
+    });
+
+    it("uses DD_SERVICE for API Gateway events", () => {
+      const inferrer = new SpanInferrer(mockWrapper as unknown as TracerWrapper);
+      inferrer.createInferredSpan(apiGatewayV1, {} as any, {} as SpanContext);
+      expect(getStartSpanServiceTag(1)).toBe("mock-lambda-service");
+    });
+
+    it("uses DD_SERVICE for Lambda Function URL events", () => {
+      const inferrer = new SpanInferrer(mockWrapper as unknown as TracerWrapper);
+      inferrer.createInferredSpan(functionUrlEvent, {} as any, {} as SpanContext);
+      expect(getStartSpanServiceTag(1)).toBe("mock-lambda-service");
+    });
+
+    it("uses DD_SERVICE for S3 events", () => {
+      const inferrer = new SpanInferrer(mockWrapper as unknown as TracerWrapper);
+      inferrer.createInferredSpan(s3Event, {} as any, {} as SpanContext);
+      expect(getStartSpanServiceTag(1)).toBe("mock-lambda-service");
+    });
+
+    it("lets an explicit DD_SERVICE_MAPPING entry win over DD_SERVICE", () => {
+      process.env.DD_SERVICE_MAPPING = "lambda_sqs:remapped-queue-service";
+      const inferrer = new SpanInferrer(mockWrapper as unknown as TracerWrapper);
+      inferrer.createInferredSpan(sqsEvent, {} as any, {} as SpanContext);
+      expect(getStartSpanServiceTag(1)).toBe("remapped-queue-service");
+    });
+
+    it("falls back to the AWS resource name when DD_SERVICE is unset", () => {
+      delete process.env[DD_SERVICE_ENV_VAR];
+      const inferrer = new SpanInferrer(mockWrapper as unknown as TracerWrapper);
+      inferrer.createInferredSpan(sqsEvent, {} as any, {} as SpanContext);
+      expect(getStartSpanServiceTag(1)).toBe("MyQueue");
+    });
+
+    it("takes precedence over DD_TRACE_AWS_SERVICE_REPRESENTATION_ENABLED=false", () => {
+      process.env.DD_TRACE_AWS_SERVICE_REPRESENTATION_ENABLED = "false";
+      const inferrer = new SpanInferrer(mockWrapper as unknown as TracerWrapper);
+      inferrer.createInferredSpan(sqsEvent, {} as any, {} as SpanContext);
+      expect(getStartSpanServiceTag(1)).toBe("mock-lambda-service");
+    });
+  });
+
+  describe("when DD_TRACE_REMOVE_INTEGRATION_SERVICE_NAMES_ENABLED is not set", () => {
+    it("leaves the AWS resource name in place", () => {
+      const inferrer = new SpanInferrer(mockWrapper as unknown as TracerWrapper);
+      inferrer.createInferredSpan(sqsEvent, {} as any, {} as SpanContext);
+      expect(getStartSpanServiceTag(1)).toBe("MyQueue");
+    });
+  });
+
   it("extracts service name from event when service mapping has incorrect delimiters", () => {
     process.env.DD_SERVICE_MAPPING = "key1-value1,key2=value2";
     const inferrer = new SpanInferrer(mockWrapper as unknown as TracerWrapper);

src/trace/span-inferrer.ts

@@ -88,6 +88,14 @@ export class SpanInferrer {
       return mappedService;
     }
 
+    // When integration service names are removed, inferred (synthetic) spans use
+    // the base service name (DD_SERVICE) instead of the AWS resource/instance
+    // representation.
+    const ddService = process.env[DD_SERVICE_ENV_VAR]?.trim();
+    if (SpanInferrer.removeIntegrationServiceNamesEnabled() && ddService) {
+      return ddService;
+    }
+
     if (
       process.env.DD_TRACE_AWS_SERVICE_REPRESENTATION_ENABLED === "false" ||
       process.env.DD_TRACE_AWS_SERVICE_REPRESENTATION_ENABLED === "0"
@@ -98,6 +106,11 @@ export class SpanInferrer {
     return extractedKey?.trim() ? extractedKey : fallback;
   }
 
+  private static removeIntegrationServiceNamesEnabled(): boolean {
+    const value = process.env.DD_TRACE_REMOVE_INTEGRATION_SERVICE_NAMES_ENABLED;
+    return value === "true" || value === "1";
+  }
+
   createInferredSpanForApiGateway(
     event: any,
     context: Context | undefined,