feat: support context propagation in bluebird

src/config.ts

@@ -254,6 +254,7 @@ export const defaultConfig = {
   maximumLabelValueSize: 512,
   plugins: {
     // enable all by default
+    'bluebird': path.join(pluginDirectory, 'plugin-bluebird.js'),
     'connect': path.join(pluginDirectory, 'plugin-connect.js'),
     'express': path.join(pluginDirectory, 'plugin-express.js'),
     'generic-pool': path.join(pluginDirectory, 'plugin-generic-pool.js'),

src/plugins/plugin-bluebird.ts

@@ -0,0 +1,30 @@
+import * as shimmer from 'shimmer';
+
+import {PluginTypes} from '..';
+
+import {bluebird_3} from './types';
+
+type BluebirdModule = typeof bluebird_3&{prototype: {_then: Function;}};
+
+const plugin: PluginTypes.Plugin = [{
+  // Bluebird is a class.
+  // tslint:disable-next-line:variable-name
+  patch: (Bluebird, tracer) => {
+    // any is a type arg; args are type checked when read directly, otherwise
+    // passed through to a function with the same type signature.
+    // tslint:disable:no-any
+    const wrapIfFunction = (fn: any) =>
+        typeof fn === 'function' ? tracer.wrap(fn) : fn;
+    shimmer.wrap(Bluebird.prototype, '_then', (thenFn: Function) => {
+      // Inherit context from the call site of .then().
+      return function<T>(this: bluebird_3<T>, ...args: any[]) {
+        return thenFn.apply(this, [
+          wrapIfFunction(args[0]), wrapIfFunction(args[1]), ...args.slice(2)
+        ]);
+      };
+    });
+    // tslint:enable:no-any
+  }
+} as PluginTypes.Monkeypatch<BluebirdModule>];
+
+export = plugin;

tsconfig.json

@@ -9,6 +9,7 @@
   "include": [
     "src/*.ts",
     "src/cls/*.ts",
+    "src/plugins/plugin-bluebird.ts",
     "src/plugins/plugin-connect.ts",
     "src/plugins/plugin-express.ts",
     "src/plugins/plugin-grpc.ts",