feat: allow enabling instrumentations selected via environment variable

Closes open-telemetry#1672

metapackages/auto-instrumentations-node/README.md

@@ -75,6 +75,21 @@ For example, to enable only the `env`, `host` detectors:
 export OTEL_NODE_RESOURCE_DETECTORS="env,host"
 ```
 
+
+By default, all [Supported Instrumentations](#supported-instrumentations) are enabled,
+but you can use the environment variable `OTEL_ENABLED_NODE_INSTRUMENTATIONS` to enable only certain instrumentations
+by providing a comma-separated list of the instrumentation package names without the `@opentelemetry/instrumentation-` prefix.
+
+For example, to enable only
+[@opentelemetry/instrumentation-http](https://github.com/open-telemetry/opentelemetry-js/tree/main/packages/opentelemetry-instrumentation-http)
+and [@opentelemetry/instrumentation-nestjs-core](https://github.com/open-telemetry/opentelemetry-js-contrib/tree/main/plugins/node/opentelemetry-instrumentation-nestjs-core)
+instrumentations:
+
+```shell
+export OTEL_ENABLED_NODE_INSTRUMENTATIONS="http,nestjs-core"
+```
+
+
 To enable logging for troubleshooting, set the log level by setting the `OTEL_LOG_LEVEL` environment variable to one of the following:
 
 - `none`

metapackages/auto-instrumentations-node/src/utils.ts

@@ -136,6 +136,7 @@ export function getNodeAutoInstrumentations(
   inputConfigs: InstrumentationConfigMap = {}
 ): Instrumentation[] {
   checkManuallyProvidedInstrumentationNames(Object.keys(inputConfigs));
+  const enabledInstrumentationsFromEnv = getEnabledInstrumentationsFromEnv();
 
   const instrumentations: Instrumentation[] = [];
 
@@ -146,7 +147,10 @@ export function getNodeAutoInstrumentations(
     // Defaults are defined by the instrumentation itself
     const userConfig: any = inputConfigs[name] ?? {};
 
-    if (userConfig.enabled === false) {
+    if (
+      userConfig.enabled === false ||
+      !enabledInstrumentationsFromEnv.includes(name)
+    ) {
       diag.debug(`Disabling instrumentation for ${name}`);
       continue;
     }
@@ -172,6 +176,24 @@ function checkManuallyProvidedInstrumentationNames(
   }
 }
 
+/**
+ * Returns the list of instrumentations that are enabled based on the environment variable.
+ */
+function getEnabledInstrumentationsFromEnv() {
+  if (!process.env.OTEL_ENABLED_NODE_INSTRUMENTATIONS) {
+    return Object.keys(InstrumentationMap);
+  }
+
+  const instrumentationsFromEnv = process.env.OTEL_ENABLED_NODE_INSTRUMENTATIONS.split(
+    ','
+  ).map(
+    instrumentationPkgSuffix =>
+      `@opentelemetry/instrumentation-${instrumentationPkgSuffix.trim()}`
+  );
+  checkManuallyProvidedInstrumentationNames(instrumentationsFromEnv);
+  return instrumentationsFromEnv;
+}
+
 export function getResourceDetectorsFromEnv(): Array<Detector | DetectorSync> {
   const resourceDetectors = new Map<
     string,

metapackages/auto-instrumentations-node/test/utils.test.ts

@@ -70,6 +70,24 @@ describe('utils', () => {
       assert.strictEqual(instrumentation, undefined);
     });
 
+    it('should return only instrumentations enabled via OTEL_ENABLED_NODE_INSTRUMENTATIONS environment variable', () => {
+      process.env.OTEL_ENABLED_NODE_INSTRUMENTATIONS = 'http,aws-sdk, nestjs-core'; // separator with and without whitespaces should be allowed
+      try {
+        const instrumentations = getNodeAutoInstrumentations();
+
+        assert.deepStrictEqual(
+          new Set(instrumentations.map(i => i.instrumentationName)),
+          new Set([
+            '@opentelemetry/instrumentation-http',
+            '@opentelemetry/instrumentation-aws-sdk',
+            '@opentelemetry/instrumentation-nestjs-core',
+          ])
+        );
+      } finally {
+        delete process.env.OTEL_ENABLED_NODE_INSTRUMENTATIONS;
+      }
+    });
+
     it('should show error for none existing instrumentation', () => {
       const spy = sinon.stub(diag, 'error');
       const name = '@opentelemetry/instrumentation-http2';