feat: implement W3C Correlation Context propagator

Signed-off-by: Ruben Vargas <ruben.vp8510@gmail.com>

packages/opentelemetry-core/src/distribute-context/distribute-context.ts

@@ -0,0 +1,37 @@
+/*!
+ * Copyright 2020, 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 { DistributedContext } from '@opentelemetry/api';
+import { Context } from '@opentelemetry/scope-base';
+
+const DISTRIBUTE_CONTEXTS = Context.createKey(
+ 'OpenTelemetry Distributed Contexts Key'
+);
+
+export function getDistributedContext(
+ context: Context
+): DistributedContext | undefined {
+ return (
+ (context.getValue(DISTRIBUTE_CONTEXTS) as DistributedContext) || undefined
+ );
+}
+
+export function setDistributedContext(
+ context: Context,
+ distributedContext: DistributedContext
+): Context {
+ return context.setValue(DISTRIBUTE_CONTEXTS, distributedContext);
+}

packages/opentelemetry-core/src/distribute-context/propagation/HttpTraceContext.ts

@@ -0,0 +1,74 @@
+/*!
+ * Copyright 2020, 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,
+ DistributedContext,
+} from '@opentelemetry/api';
+
+import {
+ getDistributedContext,
+ setDistributedContext,
+} from '../distribute-context';
+
+export const CORRELATION_CONTEXT_HEADER = 'Correlation-Context';
+
+/**
+ * Propagates {@link DistributedContext} through Context format propagation.
+ *
+ * Based on the Correlation Context specification:
+ * https://w3c.github.io/correlation-context/
+ */
+export class HttpTraceContext implements HttpTextFormat {
+ inject(context: Context, carrier: Carrier) {
+ const distContext = getDistributedContext(context);
+ if (distContext) {
+ const headerValue = Object.keys(distContext)
+ .map(
+ (key: string) =>
+ `${encodeURIComponent(key)}=${encodeURIComponent(
+ distContext[key].value
+ )}`
+ )
+ .join(',');
+ if (headerValue.length > 0) {
+ carrier[CORRELATION_CONTEXT_HEADER] = headerValue;
+ }
+ }
+ }
+
+ extract(context: Context, carrier: Carrier): Context {
+ const headerValue: string = carrier[CORRELATION_CONTEXT_HEADER] as string;
+ const distributedContext: DistributedContext = {};
+ if (headerValue.length > 0) {
+ headerValue.split(',').forEach(entry => {
+ const valueProps = entry.split(';');
+ if (valueProps.length > 0) {
+ const keyPair = valueProps[0].split('=');
+ const key = decodeURIComponent(keyPair[0].trim());
+ let value = decodeURIComponent(keyPair[1].trim());
+ if (valueProps.length > 1) {
+ value = value + ';' + valueProps.join(';');
+ }
+ distributedContext[key] = { value };
+ }
+ });
+ }
+ return setDistributedContext(context, distributedContext);
+ }
+}