feat: add composite propagator

packages/opentelemetry-core/src/context/propagation/composite.ts

@@ -0,0 +1,42 @@
+/*!
+ * Copyright 2019, 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 { Carrier, Context, HttpTextFormat } from '@opentelemetry/api';
+
+/** Combines multiple propagators into a single propagator. */
+export class CompositePropagator implements HttpTextFormat {
+  private _propagators: HttpTextFormat[];
+  constructor(...propagators: HttpTextFormat[]) {
+    this._propagators = propagators;
+  }
+
+  inject(context: Context, carrier: Carrier) {
+    for (const propagator of this._propagators) {
+      try {
+        propagator.inject(context, carrier);
+      } catch {}
+    }
+  }
+
+  extract(context: Context, carrier: Carrier): Context {
+    return this._propagators.reduce((ctx, propagator) => {
+      try {
+        return propagator.extract(ctx, carrier);
+      } catch {}
+      return ctx;
+    }, context);
+  }
+}

packages/opentelemetry-core/src/index.ts

@@ -21,6 +21,7 @@ export * from './common/types';
 export * from './version';
 export * from './context/context';
 export * from './context/propagation/B3Format';
+export * from './context/propagation/composite';
 export * from './context/propagation/HttpTraceContext';
 export * from './platform';
 export * from './trace/instrumentation/BasePlugin';

packages/opentelemetry-core/test/context/composite.test.ts

@@ -0,0 +1,164 @@
+/*!
+ * Copyright 2019, 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 { Context } from '@opentelemetry/scope-base';
+import * as assert from 'assert';
+import {
+  CompositePropagator,
+  HttpTraceContext,
+  randomSpanId,
+  randomTraceId,
+} from '../../src';
+import {
+  setExtractedSpanContext,
+  getExtractedSpanContext,
+} from '../../src/context/context';
+import {
+  B3Format,
+  X_B3_SPAN_ID,
+  X_B3_TRACE_ID,
+  X_B3_SAMPLED,
+} from '../../src/context/propagation/B3Format';
+import {
+  TRACE_PARENT_HEADER,
+  TRACE_STATE_HEADER,
+} from '../../src/context/propagation/HttpTraceContext';
+import { TraceState } from '../../src/trace/TraceState';
+import { HttpTextFormat, SpanContext } from '@opentelemetry/api';
+
+describe('Composite Propagator', () => {
+  let traceId: string;
+  let spanId: string;
+
+  beforeEach(() => {
+    traceId = randomTraceId();
+    spanId = randomSpanId();
+  });
+
+  describe('inject', () => {
+    let carrier: { [key: string]: unknown };
+    let spanContext: SpanContext;
+    let ctxWithSpanContext: Context;
+
+    beforeEach(() => {
+      carrier = {};
+      spanContext = {
+        spanId,
+        traceId,
+        traceFlags: 1,
+        traceState: new TraceState('foo=bar'),
+      };
+      ctxWithSpanContext = setExtractedSpanContext(
+        Context.ROOT_CONTEXT,
+        spanContext
+      );
+    });
+
+    it('should inject context using all configured propagators', () => {
+      const composite = new CompositePropagator(
+        new B3Format(),
+        new HttpTraceContext()
+      );
+      composite.inject(ctxWithSpanContext, carrier);
+
+      assert.strictEqual(carrier[X_B3_TRACE_ID], traceId);
+      assert.strictEqual(carrier[X_B3_SPAN_ID], spanId);
+      assert.strictEqual(carrier[X_B3_SAMPLED], 1);
+      assert.strictEqual(
+        carrier[TRACE_PARENT_HEADER],
+        `00-${traceId}-${spanId}-01`
+      );
+      assert.strictEqual(carrier[TRACE_STATE_HEADER], 'foo=bar');
+    });
+
+    it('should not throw', () => {
+      const composite = new CompositePropagator(
+        new ThrowingPropagator(),
+        new HttpTraceContext()
+      );
+      composite.inject(ctxWithSpanContext, carrier);
+
+      assert.strictEqual(
+        carrier[TRACE_PARENT_HEADER],
+        `00-${traceId}-${spanId}-01`
+      );
+    });
+  });
+
+  describe('extract', () => {
+    let carrier: { [key: string]: unknown };
+
+    beforeEach(() => {
+      carrier = {
+        [X_B3_TRACE_ID]: traceId,
+        [X_B3_SPAN_ID]: spanId,
+        [X_B3_SAMPLED]: 1,
+        [TRACE_PARENT_HEADER]: `00-${traceId}-${spanId}-01`,
+        [TRACE_STATE_HEADER]: 'foo=bar',
+      };
+    });
+
+    it('should extract context using all configured propagators', () => {
+      const composite = new CompositePropagator(
+        new B3Format(),
+        new HttpTraceContext()
+      );
+      const spanContext = getExtractedSpanContext(
+        composite.extract(Context.ROOT_CONTEXT, carrier)
+      );
+
+      if (!spanContext) {
+        throw new Error('no extracted context');
+      }
+
+      assert.strictEqual(spanContext.traceId, traceId);
+      assert.strictEqual(spanContext.spanId, spanId);
+      assert.strictEqual(spanContext.traceFlags, 1);
+      assert.strictEqual(spanContext.isRemote, true);
+      assert.strictEqual(spanContext.traceState!.get('foo'), 'bar');
+    });
+
+    it('should not throw', () => {
+      const composite = new CompositePropagator(
+        new ThrowingPropagator(),
+        new HttpTraceContext()
+      );
+      const spanContext = getExtractedSpanContext(
+        composite.extract(Context.ROOT_CONTEXT, carrier)
+      );
+
+      if (!spanContext) {
+        throw new Error('no extracted context');
+      }
+
+      assert.strictEqual(spanContext.traceId, traceId);
+      assert.strictEqual(spanContext.spanId, spanId);
+      assert.strictEqual(spanContext.traceFlags, 1);
+      assert.strictEqual(spanContext.isRemote, true);
+      assert.strictEqual(spanContext.traceState!.get('foo'), 'bar');
+    });
+  });
+});
+
+class ThrowingPropagator implements HttpTextFormat {
+  inject(context: Context, carrier: unknown) {
+    throw new Error('this propagator throws');
+  }
+
+  extract(context: Context, carrier: unknown): Context {
+    throw new Error('This propagator throws');
+  }
+}