Resource auto detection logging

packages/opentelemetry-resources/src/platform/node/detect-resources.ts

@@ -17,25 +17,63 @@
 import { Resource } from '../../Resource';
 import { envDetector, awsEc2Detector, gcpDetector } from './detectors';
 import { Detector } from '../../types';
+import { ResourceDetectionConfig } from '../../config';
+import { Logger } from '@opentelemetry/api';
+import * as util from 'util';
 
 const DETECTORS: Array<Detector> = [envDetector, awsEc2Detector, gcpDetector];
 
 /**
  * Runs all resource detectors and returns the results merged into a single
  * Resource.
+ *
+ * @param config Configuration object for resource detection
  */
-export const detectResources = async (): Promise<Resource> => {
+export const detectResources = async (
+  config: ResourceDetectionConfig = {}
+): Promise<Resource> => {
   const resources: Array<Resource> = await Promise.all(
     DETECTORS.map(d => {
       try {
-        return d.detect();
+        return d.detect(config);
       } catch {
         return Resource.empty();
       }
     })
   );
+  logResources(config.logger, resources);
   return resources.reduce(
     (acc, resource) => acc.merge(resource),
     Resource.createTelemetrySDKResource()
   );
 };
+
+/**
+ * Writes debug information about the detected resources to the logger defined in the resource detection config, if one is provided.
+ *
+ * @param logger The logger to write the debug information to.
+ * @param resources The array of resources that should be logged. Empty entried will be ignored.
+ */
+const logResources = (
+  logger: Logger | undefined,
+  resources: Array<Resource>
+) => {
+  if (logger) {
+    resources.forEach((resource, index) => {
+      // Only print populated resources
+      if (Object.keys(resource.labels).length > 0) {
+        const resourceDebugString = util.inspect(resource.labels, {
+          depth: 2,
+          breakLength: Infinity,
+          sorted: true,
+          compact: false,
+        });
+        const detectorName = DETECTORS[index].constructor
+          ? DETECTORS[index].constructor.name
+          : 'Unknown detector';
+        logger.debug(`${detectorName} found resource.`);
+        logger.debug(resourceDebugString);
+      }
+    });
+  }
+};

packages/opentelemetry-resources/src/platform/node/detectors/AwsEc2Detector.ts

@@ -18,6 +18,7 @@ import * as http from 'http';
 import { Resource } from '../../../Resource';
 import { CLOUD_RESOURCE, HOST_RESOURCE } from '../../../constants';
 import { Detector } from '../../../types';
+import { ResourceDetectionConfig } from '../../../config';
 
 /**
  * The AwsEc2Detector can be used to detect if a process is running in AWS EC2
@@ -39,7 +40,7 @@ class AwsEc2Detector implements Detector {
    * empty {@link Resource} if the connection or parsing of the identity
    * document fails.
    */
-  async detect(): Promise<Resource> {
+  async detect(config: ResourceDetectionConfig = {}): Promise<Resource> {
     try {
       const {
         accountId,

packages/opentelemetry-resources/src/platform/node/detectors/EnvDetector.ts

@@ -16,6 +16,7 @@
 
 import { Resource } from '../../../Resource';
 import { Detector, ResourceLabels } from '../../../types';
+import { ResourceDetectionConfig } from '../../../config';
 
 /**
  * EnvDetector can be used to detect the presence of and create a Resource
@@ -46,7 +47,7 @@ class EnvDetector implements Detector {
    * OTEL_RESOURCE_LABELS environment variable. Note this is an async function
    * to conform to the Detector interface.
    */
-  async detect(): Promise<Resource> {
+  async detect(config: ResourceDetectionConfig = {}): Promise<Resource> {
     try {
       const labelString = process.env.OTEL_RESOURCE_LABELS;
       if (!labelString) return Resource.empty();

packages/opentelemetry-resources/src/platform/node/detectors/GcpDetector.ts

@@ -24,14 +24,15 @@ import {
   K8S_RESOURCE,
   CONTAINER_RESOURCE,
 } from '../../../constants';
+import { ResourceDetectionConfig } from '../../../config';
 
 /**
  * The GcpDetector can be used to detect if a process is running in the Google
  * Cloud Platofrm and return a {@link Resource} populated with metadata about
  * the instance. Returns an empty Resource if detection fails.
  */
 class GcpDetector implements Detector {
-  async detect(): Promise<Resource> {
+  async detect(config: ResourceDetectionConfig = {}): Promise<Resource> {
     if (!(await gcpMetadata.isAvailable())) return Resource.empty();
 
     const [projectId, instanceId, zoneId, clusterName] = await Promise.all([

packages/opentelemetry-resources/src/types.ts

@@ -15,6 +15,7 @@
  */
 
 import { Resource } from './Resource';
+import { ResourceDetectionConfig } from './config';
 
 /** Interface for Resource labels  */
 export interface ResourceLabels {
@@ -26,5 +27,5 @@ export interface ResourceLabels {
  * a detector returns a Promise containing a Resource.
  */
 export interface Detector {
-  detect(): Promise<Resource>;
+  detect(config?: ResourceDetectionConfig): Promise<Resource>;
 }

packages/opentelemetry-resources/test/detect-resources.test.ts

@@ -16,6 +16,7 @@
 
 import * as nock from 'nock';
 import * as sinon from 'sinon';
+import * as assert from 'assert';
 import { URL } from 'url';
 import { Resource, detectResources } from '../src';
 import { awsEc2Detector } from '../src/platform/node/detectors';
@@ -162,4 +163,26 @@ describe('detectResources', async () => {
       stub.restore();
     });
   });
+
+  describe('with a debug logger', () => {
+    it('prints detected resources to the logger', async () => {
+      // This test depends on the env detector to be functioning as intended
+      const mockedLoggerMethod = sinon.fake();
+      await detectResources({
+        logger: {
+          debug: mockedLoggerMethod,
+          info: sinon.fake(),
+          warn: sinon.fake(),
+          error: sinon.fake(),
+        },
+      });
+
+      assert.deepStrictEqual(mockedLoggerMethod.getCall(0).args, [
+        'EnvDetector found resource.',
+      ]);
+      assert.deepStrictEqual(mockedLoggerMethod.getCall(1).args, [
+        "{\n  'service.instance.id': '627cc493',\n  'service.name': 'my-service',\n  'service.namespace': 'default',\n  'service.version': '0.0.1'\n}",
+      ]);
+    });
+  });
 });