Fix propagation breaking for https.get (#657)

shamelful copy from the http plugin code, to fix the
`https.get` same as `http.get`.

Author: loneparadox

packages/opencensus-instrumentation-https/src/https.ts

@@ -59,11 +59,26 @@ export class HttpsPlugin extends HttpPlugin {
       this.getPatchHttpsOutgoingRequest()
     );
     if (semver.satisfies(this.version, '>=8.0.0')) {
-      shimmer.wrap(
-        this.moduleExports,
-        'get',
-        this.getPatchHttpsOutgoingRequest()
-      );
+      shimmer.wrap(this.moduleExports, 'get', () => {
+        // Re-implement http.get. This needs to be done (instead of using
+        // getPatchOutgoingRequestFunction to patch it) because we need to
+        // set the trace context header before the returned ClientRequest is
+        // ended. The Node.js docs state that the only differences between
+        // request and get are that (1) get defaults to the HTTP GET method and
+        // (2) the returned request object is ended immediately. The former is
+        // already true (at least in supported Node versions up to v9), so we
+        // simply follow the latter. Ref:
+        // https://nodejs.org/dist/latest/docs/api/http.html#http_http_get_options_callback
+        // https://github.com/googleapis/cloud-trace-nodejs/blob/master/src/plugins/plugin-http.ts#L198
+        return function getTrace(
+          options: https.RequestOptions | string,
+          callback: ((res: http.IncomingMessage) => void) | undefined
+        ) {
+          const req = https.request(options, callback);
+          req.end();
+          return req;
+        };
+      });
     }
 
     return this.moduleExports;

packages/opencensus-instrumentation-https/test/test-https.ts

@@ -20,6 +20,10 @@ import {
   Span,
   SpanEventListener,
   SpanKind,
+  HeaderGetter,
+  HeaderSetter,
+  Propagation,
+  SpanContext,
 } from '@opencensus/core';
 import * as assert from 'assert';
 import * as fs from 'fs';
@@ -57,6 +61,27 @@ function customAttributeFunction(
 
 type RequestFunction = typeof https.request | typeof https.get;
 
+class DummyPropagation implements Propagation {
+  extract(getter: HeaderGetter): SpanContext {
+    return {
+      traceId: 'dummy-trace-id',
+      spanId: 'dummy-span-id',
+    } as SpanContext;
+  }
+
+  inject(setter: HeaderSetter, spanContext: SpanContext): void {
+    setter.setHeader('x-dummy-trace-id', spanContext.traceId || 'undefined');
+    setter.setHeader('x-dummy-span-id', spanContext.spanId || 'undefined');
+  }
+
+  generate(): SpanContext {
+    return {
+      traceId: 'dummy-trace-id',
+      spanId: 'dummy-span-id',
+    } as SpanContext;
+  }
+}
+
 const httpRequest = {
   request: (options: {} | string) => {
     return httpRequest.make(options, https.request);
@@ -150,7 +175,11 @@ describe('HttpsPlugin', () => {
   const log = logger.logger();
   const tracer = new CoreTracer();
   const spanVerifier = new SpanVerifier();
-  tracer.start({ samplingRate: 1, logger: log });
+  tracer.start({
+    samplingRate: 1,
+    logger: log,
+    propagation: new DummyPropagation(),
+  });
 
   it('should return a plugin', () => {
     assert.ok(plugin instanceof HttpsPlugin);
@@ -369,6 +398,19 @@ describe('HttpsPlugin', () => {
         }
       });
     });
+
+    it('should create a rootSpan for GET requests and add propagation headers', async () => {
+      nock.enableNetConnect();
+      assert.strictEqual(spanVerifier.endedSpans.length, 0);
+      await httpRequest.get(`https://google.fr/`).then(result => {
+        assert.strictEqual(spanVerifier.endedSpans.length, 1);
+        assert.ok(spanVerifier.endedSpans[0].name.indexOf('GET /') >= 0);
+
+        const span = spanVerifier.endedSpans[0];
+        assertSpanAttributes(span, 301, 'GET', 'google.fr', '/');
+      });
+      nock.disableNetConnect();
+    });
   });
 
   /** Should intercept incoming requests */