fix(instrumentation): normalize paths for internal files in scoped packages

experimental/CHANGELOG.md

@@ -16,6 +16,8 @@ All notable changes to experimental packages in this project will be documented
 ### :bug: (Bug Fix)
 
 * fix(sdk-node): allow using samplers when the exporter is defined in the environment [#4394](https://github.com/open-telemetry/opentelemetry-js/pull/4394) @JacksonWeber
+* fix(instrumentation): normalize paths for internal files in scoped packages [#4467](https://github.com/open-telemetry/opentelemetry-js/pull/4467) @pichlermarc
+  * Fixes a bug where, on Windows, internal files on scoped packages would not be instrumented.
 
 ### :books: (Refine Doc)
 

experimental/packages/opentelemetry-instrumentation/src/platform/node/instrumentation.ts

@@ -204,8 +204,9 @@ export abstract class InstrumentationBase<T = any>
     }
     // internal file
     const files = module.files ?? [];
+    const normalizedName = path.normalize(name);
     const supportedFileInstrumentations = files
-      .filter(f => f.name === name)
+      .filter(f => f.name === normalizedName)
       .filter(f =>
         isSupported(f.supportedVersions, version, module.includePrerelease)
       );

experimental/packages/opentelemetry-instrumentation/test/node/scoped-package-instrumentation.test.ts

@@ -0,0 +1,105 @@
+/*
+ * Copyright The 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 * as assert from 'assert';
+
+import {
+  InstrumentationBase,
+  InstrumentationConfig,
+  InstrumentationNodeModuleDefinition,
+  InstrumentationNodeModuleFile,
+} from '../../src';
+
+class TestInstrumentationSimple extends InstrumentationBase {
+  constructor(config: InstrumentationConfig) {
+    super('test-scoped-package-instrumentation', '0.0.1', config);
+  }
+  init() {
+    return new InstrumentationNodeModuleDefinition(
+      '@opentelemetry/scoped-test-module',
+      ['*'],
+      moduleExports => {
+        // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+        // @ts-ignore
+        moduleExports.propertyOnMainModule = 'modified string in main module';
+        return moduleExports;
+      },
+      moduleExports => {
+        return moduleExports;
+      },
+      [
+        new InstrumentationNodeModuleFile(
+          '@opentelemetry/scoped-test-module/src/internal.js',
+          ['*'],
+          moduleExports => {
+            // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+            // @ts-ignore no types
+            moduleExports.testString = 'modified internal string';
+            return moduleExports;
+          },
+          moduleExports => {
+            return moduleExports;
+          }
+        ),
+      ]
+    );
+  }
+}
+
+describe('instrumenting a scoped package', function () {
+  /**
+   * On Windows, instrumentation would fail on internal files of scoped packages.
+   * The reason: the path would include a '/' separator in the package name:
+   * - actual:   @opentelemetry/scoped-test-module\src\internal.js
+   * - expected: @opentelemetry\scoped-test-module\src\internal.js
+   * This resulted in internal files of scoped packages not being instrumented.
+   *
+   * See https://github.com/open-telemetry/opentelemetry-js/issues/4436
+   */
+  it('should patch internal file and main module', function () {
+    const instrumentation = new TestInstrumentationSimple({
+      enabled: false,
+    });
+    instrumentation.enable();
+
+    const { getString } = require('@opentelemetry/scoped-test-module');
+
+    assert.strictEqual(getString(), 'from index.js: modified internal string');
+  });
+
+  /**
+   * Normalizing everything passed to onRequire() from RequireInTheMiddleSingleton would cause main modules from a
+   * scoped package not to be instrumented.
+   * The reason: we'd check:
+   * '@opentelemetry\scoped-test-module' === '@opentelemetry/scoped-test-module'
+   *
+   * then determine that since this evaluates to false, this is not the main module, and we'd never instrument it.
+   *
+   * Therefore, the fix to the above test (internal files) is not to normalize everything passed to onRequire()
+   */
+  it('should patch main module', function () {
+    const instrumentation = new TestInstrumentationSimple({
+      enabled: false,
+    });
+    instrumentation.enable();
+
+    const {
+      propertyOnMainModule,
+    } = require('@opentelemetry/scoped-test-module');
+
+    assert.strictEqual(propertyOnMainModule, 'modified string in main module');
+  });
+});