Add Service and Environment dimensions to EMF metrics

When both OTEL_AWS_APPLICATION_SIGNALS_ENABLED and
OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED are set to true,
EMF metrics will now include Service and Environment as dimensions:

- Service: extracted from service.name resource attribute,
  falls back to "UnknownService"
- Environment: extracted from deployment.environment resource
  attribute, falls back to "lambda:default"
- Dimensions are not added if user already set them (case-insensitive)

For Lambda, both env vars default to true via otel-instrument wrapper.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: syed-ahsan-ishtiaque

CHANGELOG.md

@@ -13,6 +13,11 @@ If your change does not need a CHANGELOG entry, add the "skip changelog" label t
 
 ## Unreleased
 
+### Enhancements
+
+- Add Service and Environment dimensions to EMF metrics when Application Signals is enabled
+  ([#299](https://github.com/aws-observability/aws-otel-js-instrumentation/pull/299))
+
 ## v0.8.0 - 2025-10-08
 
 ### Enhancements

aws-distro-opentelemetry-node-autoinstrumentation/src/exporter/aws/metrics/emf-exporter-base.ts

@@ -19,7 +19,8 @@ import {
   ResourceMetrics,
   SumMetricData,
 } from '@opentelemetry/sdk-metrics';
-import { Resource } from '@opentelemetry/resources';
+import { defaultServiceName, Resource } from '@opentelemetry/resources';
+import { SEMRESATTRS_DEPLOYMENT_ENVIRONMENT, SEMRESATTRS_SERVICE_NAME } from '@opentelemetry/semantic-conventions';
 import { ExportResult, ExportResultCode } from '@opentelemetry/core';
 import type { LogEvent } from '@aws-sdk/client-cloudwatch-logs';
 
@@ -188,6 +189,65 @@ export abstract class EMFExporterBase implements PushMetricExporter {
     return Object.keys(attributes);
   }
 
+  /**
+   * Check if Application Signals EMF export is enabled.
+   *
+   * Returns true only if BOTH:
+   * - OTEL_AWS_APPLICATION_SIGNALS_ENABLED is true
+   * - OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED is true
+   */
+  private static isApplicationSignalsEmfExportEnabled(): boolean {
+    const appSignalsEnabled = process.env['OTEL_AWS_APPLICATION_SIGNALS_ENABLED']?.toLowerCase() === 'true';
+    const emfExportEnabled = process.env['OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED']?.toLowerCase() === 'true';
+    return appSignalsEnabled && emfExportEnabled;
+  }
+
+  /**
+   * Check if dimension already exists (case-insensitive match).
+   */
+  private hasDimensionCaseInsensitive(dimensionNames: string[], dimensionToCheck: string): boolean {
+    const dimensionLower = dimensionToCheck.toLowerCase();
+    return dimensionNames.some(dim => dim.toLowerCase() === dimensionLower);
+  }
+
+  /**
+   * Add Service and Environment dimensions if Application Signals EMF export is enabled
+   * and the dimensions are not already present (case-insensitive check).
+   */
+  private addApplicationSignalsDimensions(dimensionNames: string[], emfLog: EMFLog, resource: Resource): void {
+    if (!EMFExporterBase.isApplicationSignalsEmfExportEnabled()) {
+      return;
+    }
+
+    // Add Service dimension if not already set by user
+    if (!this.hasDimensionCaseInsensitive(dimensionNames, 'Service')) {
+      let serviceName: string = 'UnknownService';
+      if (resource?.attributes) {
+        const serviceAttr = resource.attributes[SEMRESATTRS_SERVICE_NAME];
+        if (serviceAttr && serviceAttr !== defaultServiceName()) {
+          serviceName = String(serviceAttr);
+        }
+      }
+      dimensionNames.unshift('Service');
+      emfLog['Service'] = serviceName;
+    }
+
+    // Add Environment dimension if not already set by user
+    if (!this.hasDimensionCaseInsensitive(dimensionNames, 'Environment')) {
+      let environment: string = 'lambda:default';
+      if (resource?.attributes) {
+        const envAttr = resource.attributes[SEMRESATTRS_DEPLOYMENT_ENVIRONMENT];
+        if (envAttr) {
+          environment = String(envAttr);
+        }
+      }
+      // Insert after Service if present, otherwise at beginning
+      const insertIndex = dimensionNames.includes('Service') ? 1 : 0;
+      dimensionNames.splice(insertIndex, 0, 'Environment');
+      emfLog['Environment'] = environment;
+    }
+  }
+
   /**
    * Create a hashable key from attributes for grouping metrics.
    */
@@ -443,6 +503,9 @@ export abstract class EMFExporterBase implements PushMetricExporter {
 
     const dimensionNames = this.getDimensionNames(allAttributes);
 
+    // Add Application Signals dimensions (Service and Environment) if enabled
+    this.addApplicationSignalsDimensions(dimensionNames, emfLog, resource);
+
     // Add attribute values to the root of the EMF log
     for (const [name, value] of Object.entries(allAttributes)) {
       emfLog[name] = value?.toString() ?? 'undefined';

aws-distro-opentelemetry-node-autoinstrumentation/test/exporter/aws/metrics/aws-cloudwatch-emf-exporter.test.ts

@@ -829,4 +829,255 @@ describe('TestAWSCloudWatchEMFExporter', () => {
     expect(mockSendLogEvent.calledOnce).toBeTruthy();
     expect(mockSendLogEvent.calledWith(logEvent)).toBeTruthy();
   });
+
+  describe('Application Signals EMF Dimensions', () => {
+    let savedAppSignalsEnabled: string | undefined;
+    let savedEmfExportEnabled: string | undefined;
+
+    beforeEach(() => {
+      // Save original env vars
+      savedAppSignalsEnabled = process.env['OTEL_AWS_APPLICATION_SIGNALS_ENABLED'];
+      savedEmfExportEnabled = process.env['OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED'];
+    });
+
+    afterEach(() => {
+      // Restore original env vars
+      if (savedAppSignalsEnabled === undefined) {
+        delete process.env['OTEL_AWS_APPLICATION_SIGNALS_ENABLED'];
+      } else {
+        process.env['OTEL_AWS_APPLICATION_SIGNALS_ENABLED'] = savedAppSignalsEnabled;
+      }
+      if (savedEmfExportEnabled === undefined) {
+        delete process.env['OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED'];
+      } else {
+        process.env['OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED'] = savedEmfExportEnabled;
+      }
+    });
+
+    it('TestDimensionsNotAddedWhenFeatureDisabled', () => {
+      /* Test that Service/Environment dimensions are NOT added when feature is disabled. */
+      delete process.env['OTEL_AWS_APPLICATION_SIGNALS_ENABLED'];
+      delete process.env['OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED'];
+
+      const gaugeRecord: MetricRecord = {
+        ...exporter['createMetricRecord']('test_metric', 'Count', 'Test', Date.now(), { env: 'test' }),
+        value: 50.0,
+      };
+
+      const resource = new Resource({ 'service.name': 'my-service' });
+      const result = exporter['createEmfLog']([gaugeRecord], resource, 1234567890);
+
+      // Should NOT have Service or Environment dimensions
+      expect(result).not.toHaveProperty('Service');
+      expect(result).not.toHaveProperty('Environment');
+      const cwMetrics = result._aws.CloudWatchMetrics[0];
+      expect(cwMetrics.Dimensions![0]).not.toContain('Service');
+      expect(cwMetrics.Dimensions![0]).not.toContain('Environment');
+    });
+
+    it('TestDimensionsAddedWhenBothEnvVarsEnabled', () => {
+      /* Test that Service/Environment dimensions ARE added when both env vars are enabled. */
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_ENABLED'] = 'true';
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED'] = 'true';
+
+      const gaugeRecord: MetricRecord = {
+        ...exporter['createMetricRecord']('test_metric', 'Count', 'Test', Date.now(), { env: 'test' }),
+        value: 50.0,
+      };
+
+      const resource = new Resource({ 'service.name': 'my-service', 'deployment.environment': 'production' });
+      const result = exporter['createEmfLog']([gaugeRecord], resource, 1234567890);
+
+      // Should have Service and Environment dimensions
+      expect(result).toHaveProperty('Service', 'my-service');
+      expect(result).toHaveProperty('Environment', 'production');
+      const cwMetrics = result._aws.CloudWatchMetrics[0];
+      expect(cwMetrics.Dimensions![0]).toContain('Service');
+      expect(cwMetrics.Dimensions![0]).toContain('Environment');
+      // Service should be first, Environment second
+      expect(cwMetrics.Dimensions![0][0]).toEqual('Service');
+      expect(cwMetrics.Dimensions![0][1]).toEqual('Environment');
+    });
+
+    it('TestDimensionsNotAddedWhenOnlyAppSignalsEnabled', () => {
+      /* Test that dimensions are NOT added when only APPLICATION_SIGNALS_ENABLED is set. */
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_ENABLED'] = 'true';
+      delete process.env['OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED'];
+
+      const gaugeRecord: MetricRecord = {
+        ...exporter['createMetricRecord']('test_metric', 'Count', 'Test', Date.now(), { env: 'test' }),
+        value: 50.0,
+      };
+
+      const resource = new Resource({ 'service.name': 'my-service' });
+      const result = exporter['createEmfLog']([gaugeRecord], resource, 1234567890);
+
+      expect(result).not.toHaveProperty('Service');
+      expect(result).not.toHaveProperty('Environment');
+    });
+
+    it('TestDimensionsNotAddedWhenOnlyEmfExportEnabled', () => {
+      /* Test that dimensions are NOT added when only EMF_EXPORT_ENABLED is set. */
+      delete process.env['OTEL_AWS_APPLICATION_SIGNALS_ENABLED'];
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED'] = 'true';
+
+      const gaugeRecord: MetricRecord = {
+        ...exporter['createMetricRecord']('test_metric', 'Count', 'Test', Date.now(), { env: 'test' }),
+        value: 50.0,
+      };
+
+      const resource = new Resource({ 'service.name': 'my-service' });
+      const result = exporter['createEmfLog']([gaugeRecord], resource, 1234567890);
+
+      expect(result).not.toHaveProperty('Service');
+      expect(result).not.toHaveProperty('Environment');
+    });
+
+    it('TestServiceDimensionNotOverwrittenCaseInsensitive', () => {
+      /* Test that user-set Service dimension (any case) is NOT overwritten. */
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_ENABLED'] = 'true';
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED'] = 'true';
+
+      // User sets 'service' (lowercase) as an attribute
+      const gaugeRecord: MetricRecord = {
+        ...exporter['createMetricRecord']('test_metric', 'Count', 'Test', Date.now(), { service: 'user-service' }),
+        value: 50.0,
+      };
+
+      const resource = new Resource({ 'service.name': 'resource-service' });
+      const result = exporter['createEmfLog']([gaugeRecord], resource, 1234567890);
+
+      // Should NOT add 'Service' dimension since 'service' already exists
+      expect(result).not.toHaveProperty('Service');
+      expect(result).toHaveProperty('service', 'user-service');
+      // Environment should still be added
+      expect(result).toHaveProperty('Environment', 'lambda:default');
+    });
+
+    it('TestEnvironmentDimensionNotOverwrittenCaseInsensitive', () => {
+      /* Test that user-set Environment dimension (any case) is NOT overwritten. */
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_ENABLED'] = 'true';
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED'] = 'true';
+
+      // User sets 'ENVIRONMENT' (uppercase) as an attribute
+      const gaugeRecord: MetricRecord = {
+        ...exporter['createMetricRecord']('test_metric', 'Count', 'Test', Date.now(), { ENVIRONMENT: 'user-env' }),
+        value: 50.0,
+      };
+
+      const resource = new Resource({ 'service.name': 'my-service', 'deployment.environment': 'production' });
+      const result = exporter['createEmfLog']([gaugeRecord], resource, 1234567890);
+
+      // Should NOT add 'Environment' dimension since 'ENVIRONMENT' already exists
+      expect(result).not.toHaveProperty('Environment');
+      expect(result).toHaveProperty('ENVIRONMENT', 'user-env');
+      // Service should still be added
+      expect(result).toHaveProperty('Service', 'my-service');
+    });
+
+    it('TestServiceFallbackToUnknownService', () => {
+      /* Test that Service falls back to UnknownService when resource has no service.name. */
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_ENABLED'] = 'true';
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED'] = 'true';
+
+      const gaugeRecord: MetricRecord = {
+        ...exporter['createMetricRecord']('test_metric', 'Count', 'Test', Date.now(), { env: 'test' }),
+        value: 50.0,
+      };
+
+      // Resource without service.name
+      const resource = new Resource({});
+      const result = exporter['createEmfLog']([gaugeRecord], resource, 1234567890);
+
+      expect(result).toHaveProperty('Service', 'UnknownService');
+    });
+
+    it('TestServiceFallbackWhenUnknownServicePattern', () => {
+      /* Test that Service falls back to UnknownService when resource has OTel default service name. */
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_ENABLED'] = 'true';
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED'] = 'true';
+
+      const gaugeRecord: MetricRecord = {
+        ...exporter['createMetricRecord']('test_metric', 'Count', 'Test', Date.now(), { env: 'test' }),
+        value: 50.0,
+      };
+
+      // Resource with OTel default service name pattern
+      const { defaultServiceName } = require('@opentelemetry/resources');
+      const resource = new Resource({ 'service.name': defaultServiceName() });
+      const result = exporter['createEmfLog']([gaugeRecord], resource, 1234567890);
+
+      expect(result).toHaveProperty('Service', 'UnknownService');
+    });
+
+    it('TestEnvironmentFallbackToLambdaDefault', () => {
+      /* Test that Environment falls back to lambda:default when not set in resource. */
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_ENABLED'] = 'true';
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED'] = 'true';
+
+      const gaugeRecord: MetricRecord = {
+        ...exporter['createMetricRecord']('test_metric', 'Count', 'Test', Date.now(), { env: 'test' }),
+        value: 50.0,
+      };
+
+      // Resource without deployment.environment
+      const resource = new Resource({ 'service.name': 'my-service' });
+      const result = exporter['createEmfLog']([gaugeRecord], resource, 1234567890);
+
+      expect(result).toHaveProperty('Environment', 'lambda:default');
+    });
+
+    it('TestEnvironmentExtractedFromResource', () => {
+      /* Test that Environment is extracted from deployment.environment resource attribute. */
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_ENABLED'] = 'true';
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED'] = 'true';
+
+      const gaugeRecord: MetricRecord = {
+        ...exporter['createMetricRecord']('test_metric', 'Count', 'Test', Date.now(), { env: 'test' }),
+        value: 50.0,
+      };
+
+      const resource = new Resource({ 'service.name': 'my-service', 'deployment.environment': 'staging' });
+      const result = exporter['createEmfLog']([gaugeRecord], resource, 1234567890);
+
+      expect(result).toHaveProperty('Environment', 'staging');
+    });
+
+    it('TestDimensionOrderServiceThenEnvironment', () => {
+      /* Test that Service comes before Environment in dimensions array. */
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_ENABLED'] = 'true';
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED'] = 'true';
+
+      const gaugeRecord: MetricRecord = {
+        ...exporter['createMetricRecord']('test_metric', 'Count', 'Test', Date.now(), { existing_dim: 'value' }),
+        value: 50.0,
+      };
+
+      const resource = new Resource({ 'service.name': 'my-service', 'deployment.environment': 'prod' });
+      const result = exporter['createEmfLog']([gaugeRecord], resource, 1234567890);
+
+      const cwMetrics = result._aws.CloudWatchMetrics[0];
+      // Dimensions should be: ['Service', 'Environment', 'existing_dim']
+      expect(cwMetrics.Dimensions![0][0]).toEqual('Service');
+      expect(cwMetrics.Dimensions![0][1]).toEqual('Environment');
+      expect(cwMetrics.Dimensions![0][2]).toEqual('existing_dim');
+    });
+
+    it('TestEnvVarsCaseInsensitive', () => {
+      /* Test that env var values are case-insensitive (TRUE, True, true all work). */
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_ENABLED'] = 'TRUE';
+      process.env['OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED'] = 'True';
+
+      const gaugeRecord: MetricRecord = {
+        ...exporter['createMetricRecord']('test_metric', 'Count', 'Test', Date.now(), { env: 'test' }),
+        value: 50.0,
+      };
+
+      const resource = new Resource({ 'service.name': 'my-service' });
+      const result = exporter['createEmfLog']([gaugeRecord], resource, 1234567890);
+
+      expect(result).toHaveProperty('Service', 'my-service');
+      expect(result).toHaveProperty('Environment', 'lambda:default');
+    });
+  });
 });

lambda-layer/packages/layer/scripts/otel-instrument

@@ -76,6 +76,11 @@ if [ -z "${OTEL_AWS_APPLICATION_SIGNALS_ENABLED}" ]; then
     export OTEL_AWS_APPLICATION_SIGNALS_ENABLED="true";
 fi
 
+# - Set Application Signals EMF export configuration (adds Service and Environment dimensions)
+if [ -z "${OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED}" ]; then
+    export OTEL_AWS_APPLICATION_SIGNALS_EMF_EXPORT_ENABLED="true";
+fi
+
 # - Disable otel metrics export by default
 if [ -z "${OTEL_METRICS_EXPORTER}" ]; then
     export OTEL_METRICS_EXPORTER="none";