From 19bd6c379d9f2b5bc0c19043eede467f162775cd Mon Sep 17 00:00:00 2001
From: Naseem <naseem@transit.app>
Date: Tue, 28 Apr 2020 13:32:23 -0400
Subject: [PATCH] feat: 2 level merge of user supplied and default plugin
 configs

Signed-off-by: Naseem <naseem@transit.app>
---
 .../src/NodeTracerProvider.ts                 | 24 ++++++++++++++++---
 .../test/NodeTracerProvider.test.ts           |  5 +++-
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/packages/opentelemetry-node/src/NodeTracerProvider.ts b/packages/opentelemetry-node/src/NodeTracerProvider.ts
index 29eb6edad04..c58e7e962b9 100644
--- a/packages/opentelemetry-node/src/NodeTracerProvider.ts
+++ b/packages/opentelemetry-node/src/NodeTracerProvider.ts
@@ -20,7 +20,7 @@ import {
   SDKRegistrationConfig,
 } from '@opentelemetry/tracing';
 import { DEFAULT_INSTRUMENTATION_PLUGINS, NodeTracerConfig } from './config';
-import { PluginLoader } from './instrumentation/PluginLoader';
+import { PluginLoader, Plugins } from './instrumentation/PluginLoader';
 
 /**
  * Register this TracerProvider for use with the OpenTelemetry API.
@@ -40,10 +40,28 @@ export class NodeTracerProvider extends BasicTracerProvider {
 
     this._pluginLoader = new PluginLoader(this, this.logger);
 
-    // Shallow-merge default plugins with user supplied config
+    /**
+     * For user supplied config of plugin(s) that are loaded by default,
+     * merge the user supplied and default configs of said plugin(s)
+     */
+    let mergedUserSuppliedPlugins: Plugins = {};
+
+    for (const plugin in config.plugins) {
+      if (DEFAULT_INSTRUMENTATION_PLUGINS.hasOwnProperty(plugin)) {
+        mergedUserSuppliedPlugins[plugin] = {
+          ...DEFAULT_INSTRUMENTATION_PLUGINS[plugin],
+          ...config.plugins[plugin],
+        };
+      } else {
+        // TODO: enable non-default but user-configured plugins unless
+        // explicitly disabled
+        mergedUserSuppliedPlugins[plugin] = config.plugins[plugin];
+      }
+    }
+
     this._pluginLoader.load({
       ...DEFAULT_INSTRUMENTATION_PLUGINS,
-      ...config.plugins,
+      ...mergedUserSuppliedPlugins,
     });
   }
 
diff --git a/packages/opentelemetry-node/test/NodeTracerProvider.test.ts b/packages/opentelemetry-node/test/NodeTracerProvider.test.ts
index 397b423e12f..cacda25131a 100644
--- a/packages/opentelemetry-node/test/NodeTracerProvider.test.ts
+++ b/packages/opentelemetry-node/test/NodeTracerProvider.test.ts
@@ -80,7 +80,7 @@ describe('NodeTracerProvider', () => {
       assert.ok(provider instanceof NodeTracerProvider);
     });
 
-    it('should load user configured and default plugins that have been shallowly merged', () => {
+    it('should load a merge of user configured and default plugins', () => {
       provider = new NodeTracerProvider({
         logger: new NoopLogger(),
         plugins: {
@@ -95,6 +95,9 @@ describe('NodeTracerProvider', () => {
             ignoreMethods: [],
             ignoreUrls: [],
           },
+          http: {
+            path: '@opentelemetry/plugin-http-module',
+          },
         },
       });
       const pluginLoader = provider['_pluginLoader'];