feat: added env variable to require only specific libraries

refs open-telemetry#3655 - added process.env.OTEL_REQUIRE_ONLY for e.g. b2b usages - useful when you only want to use specific otel instrumentations
kirrg001 · Mar 10, 2023 · fd1e12c · fd1e12c
1 parent ecb5ebe
commit fd1e12c
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -8,6 +8,7 @@ For experimental package changes, see the [experimental CHANGELOG](experimental/
 ## Unreleased
 
 * feat: collect host id for non-cloud environments [#3575](https://github.com/open-telemetry/opentelemetry-js/pull/3575) @mwear
+* feat: added env variable to require only specific libraries [#3666](https://github.com/open-telemetry/opentelemetry-js/pull/3666) @kirrg001
 
 ### :boom: Breaking Change
 

diff --git a/...l/packages/opentelemetry-instrumentation/src/platform/node/RequireInTheMiddleSingleton.ts b/...l/packages/opentelemetry-instrumentation/src/platform/node/RequireInTheMiddleSingleton.ts
@@ -51,6 +51,7 @@ const isMocha = [
  * on the performance of instrumentation hooks being applied.
  */
 export class RequireInTheMiddleSingleton {
+  private hook?: RequireInTheMiddle.Hooked;
   private _moduleNameTrie: ModuleNameTrie = new ModuleNameTrie();
   private static _instance?: RequireInTheMiddleSingleton;
 
@@ -59,9 +60,15 @@ export class RequireInTheMiddleSingleton {
   }
 
   private _initialize() {
-    RequireInTheMiddle(
-      // Intercept all `require` calls; we will filter the matching ones below
-      null,
+    // A list of strings separated by comma e.g. fastify,fs
+    const modules = process.env.OTEL_REQUIRE_ONLY
+      ? process.env.OTEL_REQUIRE_ONLY.split(',').map(i => i.trim())
+      : null;
+
+    this.hook = RequireInTheMiddle(
+      // Intercept all `require` calls; we will filter the matching ones below.
+      // Alternatively you can set an env variable to only listen for specific libs.
+      modules,
       { internals: true },
       (exports, name, basedir) => {
         // For internal files on Windows, `name` will use backslash as the path separator
@@ -84,6 +91,15 @@ export class RequireInTheMiddleSingleton {
     );
   }
 
+  /**
+   * Deregister require-in-the-middle hook.
+   * @returns
+   */
+  unhook() {
+    if (!this.hook) return;
+    this.hook.unhook();
+  }
+
   /**
    * Register a hook with `require-in-the-middle`
    *

diff --git a/...ntal/packages/opentelemetry-instrumentation/test/node/RequireInTheMiddleSingleton.test.ts b/...ntal/packages/opentelemetry-instrumentation/test/node/RequireInTheMiddleSingleton.test.ts
@@ -20,8 +20,6 @@ import * as path from 'path';
 import * as RequireInTheMiddle from 'require-in-the-middle';
 import { RequireInTheMiddleSingleton } from '../../src/platform/node/RequireInTheMiddleSingleton';
 
-const requireInTheMiddleSingleton = RequireInTheMiddleSingleton.getInstance();
-
 type AugmentedExports = {
   __ritmOnRequires?: string[];
 };
@@ -34,15 +32,25 @@ const makeOnRequiresStub = (label: string): sinon.SinonStub =>
   }) as RequireInTheMiddle.OnRequireFn);
 
 describe('RequireInTheMiddleSingleton', () => {
-  describe('register', () => {
-    const onRequireFsStub = makeOnRequiresStub('fs');
-    const onRequireFsPromisesStub = makeOnRequiresStub('fs-promises');
-    const onRequireCodecovStub = makeOnRequiresStub('codecov');
-    const onRequireCodecovLibStub = makeOnRequiresStub('codecov-lib');
-    const onRequireCpxStub = makeOnRequiresStub('cpx');
-    const onRequireCpxLibStub = makeOnRequiresStub('cpx-lib');
+  describe('default', () => {
+    let requireInTheMiddleSingleton: RequireInTheMiddleSingleton;
+    let onRequireFsStub: sinon.SinonStub;
+    let onRequireFsPromisesStub: sinon.SinonStub;
+    let onRequireCodecovStub: sinon.SinonStub;
+    let onRequireCodecovLibStub: sinon.SinonStub;
+    let onRequireCpxStub: sinon.SinonStub;
+    let onRequireCpxLibStub: sinon.SinonStub;
 
     before(() => {
+      onRequireFsStub = makeOnRequiresStub('fs');
+      onRequireFsPromisesStub = makeOnRequiresStub('fs-promises');
+      onRequireCodecovStub = makeOnRequiresStub('codecov');
+      onRequireCodecovLibStub = makeOnRequiresStub('codecov-lib');
+      onRequireCpxStub = makeOnRequiresStub('cpx');
+      onRequireCpxLibStub = makeOnRequiresStub('cpx-lib');
+
+      requireInTheMiddleSingleton = RequireInTheMiddleSingleton.getInstance();
+
       requireInTheMiddleSingleton.register('fs', onRequireFsStub);
       requireInTheMiddleSingleton.register(
         'fs/promises',
@@ -69,6 +77,10 @@ describe('RequireInTheMiddleSingleton', () => {
       onRequireCpxLibStub.resetHistory();
     });
 
+    after(() => {
+      requireInTheMiddleSingleton.unhook();
+    });
+
     it('should return a hooked object', () => {
       const moduleName = 'm';
       const onRequire = makeOnRequiresStub('m');
@@ -179,4 +191,71 @@ describe('RequireInTheMiddleSingleton', () => {
       });
     });
   });
+
+  describe('with OTEL_REQUIRE_ONLY set', () => {
+    let requireInTheMiddleSingleton: RequireInTheMiddleSingleton;
+    let onRequireFsStub: sinon.SinonStub;
+    let onRequireCodecovStub: sinon.SinonStub;
+
+    describe('single module', function () {
+      before(() => {
+        onRequireFsStub = makeOnRequiresStub('fs');
+        onRequireCodecovStub = makeOnRequiresStub('codecov');
+
+        process.env.OTEL_REQUIRE_ONLY = 'fs';
+        requireInTheMiddleSingleton = RequireInTheMiddleSingleton.getInstance();
+
+        requireInTheMiddleSingleton.register('fs', onRequireFsStub);
+        requireInTheMiddleSingleton.register('codecov', onRequireCodecovStub);
+      });
+
+      beforeEach(() => {
+        onRequireFsStub.resetHistory();
+        onRequireCodecovStub.resetHistory();
+      });
+
+      after(() => {
+        delete process.env.OTEL_REQUIRE_ONLY;
+        requireInTheMiddleSingleton.unhook();
+      });
+
+      it('should call `onRequire` for fs', () => {
+        require('fs');
+        require('codecov');
+
+        assert.equal(onRequireFsStub.called, true);
+        assert.equal(onRequireCodecovStub.called, false);
+      });
+    });
+
+    describe('multiple modules', function () {
+      before(() => {
+        onRequireFsStub = makeOnRequiresStub('fs');
+        onRequireCodecovStub = makeOnRequiresStub('codecov');
+
+        process.env.OTEL_REQUIRE_ONLY = 'fs,codecov';
+        requireInTheMiddleSingleton = RequireInTheMiddleSingleton.getInstance();
+
+        requireInTheMiddleSingleton.register('fs', onRequireFsStub);
+        requireInTheMiddleSingleton.register('codecov', onRequireCodecovStub);
+      });
+
+      beforeEach(() => {
+        onRequireFsStub.resetHistory();
+        onRequireCodecovStub.resetHistory();
+      });
+
+      after(() => {
+        delete process.env.OTEL_REQUIRE_ONLY;
+      });
+
+      it('should call `onRequire` for codecov & fs', () => {
+        require('fs');
+        require('codecov');
+
+        assert.equal(onRequireFsStub.called, true);
+        assert.equal(onRequireCodecovStub.called, true);
+      });
+    });
+  });
 });