add resourceFactory option for traces (#938)

* add resource factory for traces

* update resource factory docs

docs/advanced-config.md

@@ -80,6 +80,8 @@ The following config options can be set by passing them as tracing arguments to
 
 - `tracing.tracerConfig`: A JS object that is merged into the default tracer config replacing any existing keys. It's passed to the tracer provider during initialization. This can be used to customize the tracer provider or tracer. Must satisfy [`TracerConfig` interface](https://github.com/open-telemetry/opentelemetry-js/blob/71ba83a0dc51118e08e3148c788b81fe711003e7/packages/opentelemetry-tracing/src/types.ts#L26)
 
+- `tracing.resourceFactory`: A function that is invoked with the default resource detected from the environment. Can be used to change the detected attributes or return a completely new resource.
+
 - `tracing.spanExporterFactory`: A function that accepts the tracing options. Returns a new instance of SpanExporter. When set, this function is used to create a new exporter and the returned exporter will be used in the pipeline.
 
 - `tracing.spanProcessorFactory`: Returns a SpanProcessor instance or an array of SpanProcessor instances. When set, this function is be used to create one or more span processors. The returned processors are added to the global tracer provider and configured to process all spans generated by any tracer provider by the global provider. The function creates a new span exporter and uses it with each processor it creates. It may call `options.spanExporterFactory(options)` to create a new exporter as configured by the user.

src/metrics/index.ts

@@ -39,9 +39,9 @@ import * as util from 'util';
 import { detect as detectResource } from '../resource';
 import { SemanticResourceAttributes } from '@opentelemetry/semantic-conventions';
 import { ConsoleMetricExporter } from './ConsoleMetricExporter';
+import type { ResourceFactory } from '../types';
 
 export type MetricReaderFactory = (options: MetricsOptions) => MetricReader[];
-export type ResourceFactory = (resource: Resource) => Resource;
 
 interface MetricsOptions {
   accessToken: string;

src/tracing/options.ts

@@ -35,7 +35,7 @@ import {
   getNonEmptyEnvVar,
 } from '../utils';
 import { NodeTracerConfig } from '@opentelemetry/sdk-trace-node';
-import { SemanticResourceAttributes } from '@opentelemetry/semantic-conventions';
+import { SEMRESATTRS_SERVICE_NAME } from '@opentelemetry/semantic-conventions';
 import { diag, Span, TextMapPropagator } from '@opentelemetry/api';
 import {
   CompositePropagator,
@@ -44,6 +44,7 @@ import {
 } from '@opentelemetry/core';
 import { SplunkBatchSpanProcessor } from './SplunkBatchSpanProcessor';
 import { Resource } from '@opentelemetry/resources';
+import type { ResourceFactory } from '../types';
 
 type SpanExporterFactory = (options: Options) => SpanExporter | SpanExporter[];
 
@@ -67,6 +68,7 @@ export interface Options {
   captureHttpRequestUriParams: string[] | CaptureHttpUriParameters;
   instrumentations: (Instrumentation | Instrumentation[])[];
   propagatorFactory: PropagatorFactory;
+  resourceFactory: ResourceFactory;
   serverTimingEnabled: boolean;
   spanExporterFactory: SpanExporterFactory;
   spanProcessorFactory: SpanProcessorFactory;
@@ -80,6 +82,7 @@ export const allowedTracingOptions = [
   'endpoint',
   'instrumentations',
   'propagatorFactory',
+  'resourceFactory',
   'serverTimingEnabled',
   'serviceName',
   'spanExporterFactory',
@@ -115,12 +118,15 @@ export function _setDefaultOptions(options: Partial<Options> = {}): Options {
 
   const extraTracerConfig = options.tracerConfig || {};
 
-  let resource = detectResource();
+  const envResource = detectResource();
+
+  const resourceFactory = options.resourceFactory || ((r: Resource) => r);
+  let resource = resourceFactory(envResource);
 
   const serviceName =
     options.serviceName ||
     getNonEmptyEnvVar('OTEL_SERVICE_NAME') ||
-    resource.attributes[SemanticResourceAttributes.SERVICE_NAME];
+    resource.attributes[SEMRESATTRS_SERVICE_NAME];
 
   if (!serviceName) {
     diag.warn(
@@ -132,8 +138,7 @@ export function _setDefaultOptions(options: Partial<Options> = {}): Options {
 
   resource = resource.merge(
     new Resource({
-      [SemanticResourceAttributes.SERVICE_NAME]:
-        serviceName || defaultServiceName(),
+      [SEMRESATTRS_SERVICE_NAME]: serviceName || defaultServiceName(),
     })
   );
 
@@ -172,16 +177,15 @@ export function _setDefaultOptions(options: Partial<Options> = {}): Options {
   return {
     realm: options.realm,
     endpoint: options.endpoint,
-    serviceName: String(
-      resource.attributes[SemanticResourceAttributes.SERVICE_NAME]
-    ),
+    serviceName: String(resource.attributes[SEMRESATTRS_SERVICE_NAME]),
     accessToken: options.accessToken,
     serverTimingEnabled: options.serverTimingEnabled,
     instrumentations: options.instrumentations,
     tracerConfig: tracerConfig,
     spanExporterFactory: options.spanExporterFactory,
     spanProcessorFactory: options.spanProcessorFactory,
     propagatorFactory: options.propagatorFactory,
+    resourceFactory,
     captureHttpRequestUriParams: options.captureHttpRequestUriParams,
   };
 }

src/types.ts

@@ -14,8 +14,12 @@
  * limitations under the License.
  */
 
+import type { Resource } from '@opentelemetry/resources';
+
 export type LogLevel = 'none' | 'verbose' | 'debug' | 'info' | 'warn' | 'error';
 
+export type ResourceFactory = (resource: Resource) => Resource;
+
 export type EnvVarKey =
   | 'OTEL_ATTRIBUTE_VALUE_LENGTH_LIMIT'
   | 'OTEL_BSP_SCHEDULE_DELAY'

test/options.test.ts

@@ -217,18 +217,21 @@ describe('options', () => {
     const testInstrumentation = new TestInstrumentation('inst', '1.0', {});
     const idGenerator = new TestIdGenerator();
 
+    const resourceFactory = (resource: Resource) => {
+      return resource;
+    };
+
     const options = _setDefaultOptions({
       realm: 'rlm',
       endpoint: 'custom-endpoint',
       serviceName: 'custom-service-name',
       accessToken: 'custom-access-token',
       instrumentations: [testInstrumentation],
       tracerConfig: {
-        resource: new Resource({
-          attr1: 'value',
-        }),
+        resource: new Resource({ attr1: 'value1' }),
         idGenerator: idGenerator,
       },
+      resourceFactory,
       spanExporterFactory: testSpanExporterFactory,
       spanProcessorFactory: testSpanProcessorFactory,
       propagatorFactory: testPropagatorFactory,
@@ -242,8 +245,9 @@ describe('options', () => {
       accessToken: 'custom-access-token',
       serverTimingEnabled: true,
       instrumentations: [testInstrumentation],
+      resourceFactory,
       tracerConfig: {
-        resource: new Resource({ attr1: 'value' }),
+        resource: new Resource({ attr1: 'value1' }),
         idGenerator: idGenerator,
       },
       spanExporterFactory: testSpanExporterFactory,
@@ -259,6 +263,22 @@ describe('options', () => {
     );
   });
 
+  it('is possible to provide additional resource attributes', () => {
+    const options = _setDefaultOptions({
+      resourceFactory: (resource) => {
+        return resource.merge(
+          new Resource({ 'splunk.distro.version': 'v9001', abc: 42 })
+        );
+      },
+    });
+
+    assert.strictEqual(
+      options.tracerConfig.resource?.attributes['splunk.distro.version'],
+      'v9001'
+    );
+    assert.strictEqual(options.tracerConfig.resource?.attributes['abc'], 42);
+  });
+
   describe('OTEL_TRACES_EXPORTER', () => {
     it('accepts a single key', () => {
       process.env.OTEL_TRACES_EXPORTER = 'console';