feat(sdk-trace-base)!: drop ability to auto-instantiate propagators beyond defaults

CHANGELOG.md

@@ -52,6 +52,19 @@ For semantic convention package changes, see the [semconv CHANGELOG](packages/se
   * (user-facing): deprecated `AlwaysOffSampler` has moved to `@opentelemetry/sdk-trace-base`
   * (user-facing): deprecated `TraceIdRatioSampler` has moved to `@opentelemetry/sdk-trace-base`
   * (user-facing): deprecated `TraceIdRatioSampler` has moved to  `@opentelemetry/sdk-trace-base`
+* feat(sdk-trace-base)!: drop ability to instantiate propagators beyond defaults [#5355](https://github.com/open-telemetry/opentelemetry-js/pull/5355) @pichlermarc
+  * (user-facing): only a non-env-var based default is now used on `BasicTracerProvider#register()`.
+    * propagators can now not be configured via `OTEL_PROPAGATORS` or `window.OTEL_PROPAGATORS` anymore, please pass the propagator to `NodeTracerProvider#register()` instead.
+    * if not configured directly via code, `BasicTracerProvider#register()` will now fall back to defaults (`tracecontext` and `baggage`)
+* feat(sdk-trace-node)!: drop ability to instantiate propagators beyond defaults [#5355](https://github.com/open-telemetry/opentelemetry-js/pull/5355) @pichlermarc
+  * (user-facing): only a non-env-var based default is now used on `NodeTracerProvider#register()`.
+    * propagators can now not be configured via `OTEL_PROPAGATORS` anymore, please pass the propagator to `NodeTracerProvider#register()` instead.
+    * if not configured via code, `NodeTracerProvider#register()` will now fall back to the defaults (`tracecontext` and `baggage`)
+    * if autoconfiguration based on enviornment variables is needed, please use `NodeSDK` from `@opentelemetry/sdk-node`.
+* feat(sdk-trace-web)!: drop ability to instantiate propagators beyond defaults [#5355](https://github.com/open-telemetry/opentelemetry-js/pull/5355) @pichlermarc
+  * (user-facing): only a non-env-var based default is now used on `WebTracerProvider#register()`.
+    * propagators can now not be configured via `window.OTEL_PROPAGATORS` anymore, please pass the propagator to `WebTracerProvider#register()` instead.
+    * if not configured via code, `WebTracerProvider#register()` will now fall back to defaults (`tracecontext` and `baggage`)
 
 ### :rocket: (Enhancement)
 

experimental/CHANGELOG.md

@@ -34,6 +34,7 @@ All notable changes to experimental packages in this project will be documented
 * chore(instrumentation-grpc): remove unused findIndex() function [#5372](https://github.com/open-telemetry/opentelemetry-js/pull/5372) @cjihrig
 * refactor(otlp-exporter-base): remove unnecessary isNaN() checks [#5374](https://github.com/open-telemetry/opentelemetry-js/pull/5374) @cjihrig
 * refactor(exporter-prometheus): remove unnecessary isNaN() check [#5377](https://github.com/open-telemetry/opentelemetry-js/pull/5377) @cjihrig
+* refactor(sdk-node): move code to auto-instantiate propagators into utils [#5355](https://github.com/open-telemetry/opentelemetry-js/pull/5355) @pichlermarc
 
 ## 0.57.0
 

experimental/packages/opentelemetry-sdk-node/package.json

@@ -63,7 +63,9 @@
     "@opentelemetry/sdk-metrics": "1.30.0",
     "@opentelemetry/sdk-trace-base": "1.30.0",
     "@opentelemetry/sdk-trace-node": "1.30.0",
-    "@opentelemetry/semantic-conventions": "1.28.0"
+    "@opentelemetry/semantic-conventions": "1.28.0",
+    "@opentelemetry/propagator-jaeger": "1.30.0",
+    "@opentelemetry/propagator-b3": "1.30.0"
   },
   "peerDependencies": {
     "@opentelemetry/api": ">=1.3.0 <1.10.0"

experimental/packages/opentelemetry-sdk-node/src/sdk.ts

@@ -74,6 +74,7 @@ import {
   getResourceDetectorsFromEnv,
   getSpanProcessorsFromEnv,
   filterBlanksAndNulls,
+  getPropagatorFromEnv,
 } from './utils';
 
 /** This class represents everything needed to register a fully configured OpenTelemetry Node.js SDK */
@@ -376,7 +377,9 @@ export class NodeSDK {
           this._tracerProviderConfig?.contextManager ??
           // _tracerProviderConfig may be undefined if trace-specific settings are not provided - fall back to raw config
           this._configuration?.contextManager,
-        propagator: this._tracerProviderConfig?.textMapPropagator,
+        propagator:
+          this._tracerProviderConfig?.textMapPropagator ??
+          getPropagatorFromEnv(),
       });
     }
 

experimental/packages/opentelemetry-sdk-node/src/utils.ts

@@ -14,8 +14,13 @@
  * limitations under the License.
  */
 
-import { diag } from '@opentelemetry/api';
-import { getEnv, getEnvWithoutDefaults } from '@opentelemetry/core';
+import { diag, TextMapPropagator } from '@opentelemetry/api';
+import {
+  CompositePropagator,
+  getEnv,
+  getEnvWithoutDefaults,
+  W3CTraceContextPropagator,
+} from '@opentelemetry/core';
 import { OTLPTraceExporter as OTLPProtoTraceExporter } from '@opentelemetry/exporter-trace-otlp-proto';
 import { OTLPTraceExporter as OTLPHttpTraceExporter } from '@opentelemetry/exporter-trace-otlp-http';
 import { OTLPTraceExporter as OTLPGrpcTraceExporter } from '@opentelemetry/exporter-trace-otlp-grpc';
@@ -35,6 +40,8 @@ import {
   SpanExporter,
   SpanProcessor,
 } from '@opentelemetry/sdk-trace-base';
+import { B3InjectEncoding, B3Propagator } from '@opentelemetry/propagator-b3';
+import { JaegerPropagator } from '@opentelemetry/propagator-jaeger';
 
 const RESOURCE_DETECTOR_ENVIRONMENT = 'env';
 const RESOURCE_DETECTOR_HOST = 'host';
@@ -180,3 +187,66 @@ export function getSpanProcessorsFromEnv(): SpanProcessor[] {
 
   return processors;
 }
+
+/**
+ * Get a propagator as defined by environment variables
+ */
+export function getPropagatorFromEnv(): TextMapPropagator | null | undefined {
+  // Empty and undefined MUST be treated equal.
+  if (
+    process.env.OTEL_PROPAGATORS === undefined ||
+    process.env.OTEL_PROPAGATORS?.trim() === ''
+  ) {
+    // return undefined to fall back to default
+    return undefined;
+  }
+
+  // Implementation note: this only contains specification required propagators that are actually hosted in this repo.
+  // Any other propagators (like aws, aws-lambda, should go into `@opentelemetry/auto-configuration-propagators` instead).
+  const propagatorsFactory = new Map<string, () => TextMapPropagator>([
+    ['tracecontext', () => new W3CTraceContextPropagator()],
+    ['baggage', () => new W3CTraceContextPropagator()],
+    ['b3', () => new B3Propagator()],
+    [
+      'b3multi',
+      () => new B3Propagator({ injectEncoding: B3InjectEncoding.MULTI_HEADER }),
+    ],
+    ['jaeger', () => new JaegerPropagator()],
+  ]);
+
+  // Values MUST be deduplicated in order to register a Propagator only once.
+  const uniquePropagatorNames = Array.from(new Set(getEnv().OTEL_PROPAGATORS));
+
+  const propagators = uniquePropagatorNames.map(name => {
+    const propagator = propagatorsFactory.get(name)?.();
+    if (!propagator) {
+      diag.warn(
+        `Propagator "${name}" requested through environment variable is unavailable.`
+      );
+      return undefined;
+    }
+
+    return propagator;
+  });
+
+  const validPropagators = propagators.reduce<TextMapPropagator[]>(
+    (list, item) => {
+      if (item) {
+        list.push(item);
+      }
+      return list;
+    },
+    []
+  );
+
+  if (validPropagators.length === 0) {
+    // null to signal that the default should **not** be used in its place.
+    return null;
+  } else if (uniquePropagatorNames.length === 1) {
+    return validPropagators[0];
+  } else {
+    return new CompositePropagator({
+      propagators: validPropagators,
+    });
+  }
+}

experimental/packages/opentelemetry-sdk-node/test/sdk.test.ts

@@ -414,6 +414,21 @@ describe('Node SDK', () => {
       assert.equal(actualContextManager, expectedContextManager);
       await sdk.shutdown();
     });
+
+    it('should register propagators as defined in OTEL_PROPAGATORS if trace SDK is configured', async () => {
+      process.env.OTEL_PROPAGATORS = 'b3';
+      const sdk = new NodeSDK({
+        traceExporter: new ConsoleSpanExporter(),
+        autoDetectResources: false,
+      });
+
+      sdk.start();
+
+      assert.deepStrictEqual(propagation.fields(), ['b3']);
+
+      await sdk.shutdown();
+      delete process.env.OTEL_PROPAGATORS;
+    });
   });
 
   async function waitForNumberOfMetrics(

experimental/packages/opentelemetry-sdk-node/test/utils.test.ts

@@ -0,0 +1,102 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { getPropagatorFromEnv } from '../src/utils';
+import * as assert from 'assert';
+import * as sinon from 'sinon';
+import { diag } from '@opentelemetry/api';
+
+describe('getPropagatorFromEnv', function () {
+  afterEach(() => {
+    delete process.env.OTEL_PROPAGATORS;
+    sinon.restore();
+  });
+
+  describe('should default to undefined', function () {
+    it('when not defined', function () {
+      delete process.env.OTEL_PROPAGATORS;
+
+      const propagator = getPropagatorFromEnv();
+
+      assert.deepStrictEqual(propagator, undefined);
+    });
+
+    it('on empty string', function () {
+      (process.env as any).OTEL_PROPAGATORS = '';
+
+      const propagator = getPropagatorFromEnv();
+
+      assert.deepStrictEqual(propagator, undefined);
+    });
+
+    it('on space-only string', function () {
+      (process.env as any).OTEL_PROPAGATORS = '   ';
+
+      const propagator = getPropagatorFromEnv();
+
+      assert.deepStrictEqual(propagator, undefined);
+    });
+  });
+
+  it('should return the selected propagator when one is in the list', () => {
+    process.env.OTEL_PROPAGATORS = 'tracecontext';
+    assert.deepStrictEqual(getPropagatorFromEnv()?.fields(), [
+      'traceparent',
+      'tracestate',
+    ]);
+  });
+
+  it('should return the selected propagators when multiple are in the list', () => {
+    process.env.OTEL_PROPAGATORS = 'tracecontext,baggage,b3,b3multi,jaeger';
+    assert.deepStrictEqual(getPropagatorFromEnv()?.fields(), [
+      'traceparent',
+      'tracestate',
+      'b3',
+      'x-b3-traceid',
+      'x-b3-spanid',
+      'x-b3-flags',
+      'x-b3-sampled',
+      'x-b3-parentspanid',
+      'uber-trace-id',
+    ]);
+  });
+
+  it('should return null and warn if propagators are unknown', () => {
+    const warnStub = sinon.stub(diag, 'warn');
+
+    process.env.OTEL_PROPAGATORS = 'my, unknown, propagators';
+    assert.deepStrictEqual(getPropagatorFromEnv(), null);
+    sinon.assert.calledWithExactly(
+      warnStub,
+      'Propagator "my" requested through environment variable is unavailable.'
+    );
+    sinon.assert.calledWithExactly(
+      warnStub,
+      'Propagator "unknown" requested through environment variable is unavailable.'
+    );
+    sinon.assert.calledWithExactly(
+      warnStub,
+      'Propagator "propagators" requested through environment variable is unavailable.'
+    );
+    sinon.assert.calledThrice(warnStub);
+  });
+
+  it('should return null if only "none" is selected', () => {
+    process.env.OTEL_PROPAGATORS = 'none';
+
+    assert.deepStrictEqual(getPropagatorFromEnv(), null);
+  });
+});

experimental/packages/opentelemetry-sdk-node/tsconfig.json

@@ -24,6 +24,12 @@
     {
       "path": "../../../packages/opentelemetry-exporter-zipkin"
     },
+    {
+      "path": "../../../packages/opentelemetry-propagator-b3"
+    },
+    {
+      "path": "../../../packages/opentelemetry-propagator-jaeger"
+    },
     {
       "path": "../../../packages/opentelemetry-resources"
     },