fix(otlp-exporter-base): honor env proxy settings

experimental/CHANGELOG.md

@@ -15,6 +15,7 @@ For notes on migrating to 2.x / 0.200.x see [the upgrade guide](doc/upgrade-to-2
 
 ### :bug: Bug Fixes
 
+* fix(otlp-exporter-base): honor Node.js environment proxy settings in HTTP agent factory [#6660](https://github.com/open-telemetry/opentelemetry-js/pull/6660) @cyphercodes
 * fix(configuration): do not validate `OTEL_CONFIG_FILE` value before using it for file config [#6643](https://github.com/open-telemetry/opentelemetry-js/pull/6643) @trentm
 * fix(configuration): improve how 'additionalProperties' in JSON schema is translated to TS types [#6650](https://github.com/open-telemetry/opentelemetry-js/pull/6650) @trentm
 * fix(sampler-jaeger-remote): add missing axios dep [#6656](https://github.com/open-telemetry/opentelemetry-js/pull/6656) @trentm

experimental/packages/otlp-exporter-base/src/configuration/otlp-node-http-configuration.ts

@@ -36,21 +36,54 @@ export interface OtlpNodeHttpConfiguration extends OtlpHttpConfiguration {
   userAgent?: string;
 }
 
+function hasEnvProxyEnvVar(name: string): boolean {
+  return process.env[name] != null && process.env[name] !== '';
+}
+
+function hasEnvProxyConfiguration(): boolean {
+  return (
+    process.env.NODE_USE_ENV_PROXY === '1' ||
+    hasEnvProxyEnvVar('HTTP_PROXY') ||
+    hasEnvProxyEnvVar('http_proxy') ||
+    hasEnvProxyEnvVar('HTTPS_PROXY') ||
+    hasEnvProxyEnvVar('https_proxy')
+  );
+}
+
+function getEnvProxyAgentOptions():
+  | { proxyEnv: NodeJS.ProcessEnv }
+  | undefined {
+  if (hasEnvProxyConfiguration()) {
+    // `proxyEnv` is used by Node.js' HTTP agents to honor HTTP(S)_PROXY
+    // while preserving exporter-specific agent options such as keepAlive.
+    return { proxyEnv: process.env };
+  }
+
+  return undefined;
+}
+
 export function httpAgentFactoryFromOptions(
   options: http.AgentOptions | https.AgentOptions
 ): HttpAgentFactory {
   return async protocol => {
     const isInsecure = protocol === 'http:';
     const module = isInsecure ? import('http') : import('https');
     const { Agent } = await module;
+    const envProxyAgentOptions = getEnvProxyAgentOptions();
 
     if (isInsecure) {
       // eslint-disable-next-line @typescript-eslint/no-unused-vars -- these props should not be used in agent options
       const { ca, cert, key, ...insecureOptions } =
         options as https.AgentOptions;
-      return new Agent(insecureOptions);
+      return new Agent({
+        ...insecureOptions,
+        ...envProxyAgentOptions,
+      } as http.AgentOptions);
     }
-    return new Agent(options);
+    return new Agent({
+      ...options,
+      ...envProxyAgentOptions,
+    } as https.AgentOptions);
   };
 }
 

experimental/packages/otlp-exporter-base/test/node/configuration/otlp-http-configuration.test.ts

@@ -3,10 +3,93 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 import * as assert from 'assert';
-import { mergeOtlpNodeHttpConfigurationWithDefaults } from '../../../src/configuration/otlp-node-http-configuration';
+import * as http from 'http';
+import * as https from 'https';
+import {
+  httpAgentFactoryFromOptions,
+  mergeOtlpNodeHttpConfigurationWithDefaults,
+} from '../../../src/configuration/otlp-node-http-configuration';
 import type { OtlpNodeHttpConfiguration } from '../../../src/configuration/otlp-node-http-configuration';
 import { VERSION } from '../../../src/version';
 
+const ENV_PROXY_VARIABLES = [
+  'NODE_USE_ENV_PROXY',
+  'HTTP_PROXY',
+  'http_proxy',
+  'HTTPS_PROXY',
+  'https_proxy',
+];
+
+function agentOptions(agent: http.Agent | https.Agent): any {
+  return (agent as any).options;
+}
+
+describe('httpAgentFactoryFromOptions', function () {
+  let originalEnv: Record<string, string | undefined>;
+
+  beforeEach(function () {
+    originalEnv = {};
+    for (const envVar of ENV_PROXY_VARIABLES) {
+      originalEnv[envVar] = process.env[envVar];
+      delete process.env[envVar];
+    }
+  });
+
+  afterEach(function () {
+    for (const envVar of ENV_PROXY_VARIABLES) {
+      if (originalEnv[envVar] == null) {
+        delete process.env[envVar];
+      } else {
+        process.env[envVar] = originalEnv[envVar];
+      }
+    }
+  });
+
+  it('creates protocol-specific agents with the provided options', async function () {
+    const factory = httpAgentFactoryFromOptions({ keepAlive: true });
+
+    const httpAgent = (await factory('http:')) as http.Agent;
+    const httpsAgent = (await factory('https:')) as https.Agent;
+
+    assert.ok(httpAgent instanceof http.Agent);
+    assert.ok(httpsAgent instanceof https.Agent);
+    assert.strictEqual(agentOptions(httpAgent).keepAlive, true);
+    assert.strictEqual(agentOptions(httpsAgent).keepAlive, true);
+    assert.strictEqual(agentOptions(httpAgent).proxyEnv, undefined);
+    assert.strictEqual(agentOptions(httpsAgent).proxyEnv, undefined);
+  });
+
+  it('passes proxyEnv to http agents when HTTP_PROXY is configured', async function () {
+    process.env.HTTP_PROXY = 'http://proxy.example:3128';
+    const factory = httpAgentFactoryFromOptions({ keepAlive: true });
+
+    const agent = (await factory('http:')) as http.Agent;
+
+    assert.strictEqual(agentOptions(agent).keepAlive, true);
+    assert.strictEqual(agentOptions(agent).proxyEnv, process.env);
+  });
+
+  it('passes proxyEnv to https agents when HTTPS_PROXY is configured', async function () {
+    process.env.HTTPS_PROXY = 'http://proxy.example:3128';
+    const factory = httpAgentFactoryFromOptions({ keepAlive: true });
+
+    const agent = (await factory('https:')) as https.Agent;
+
+    assert.strictEqual(agentOptions(agent).keepAlive, true);
+    assert.strictEqual(agentOptions(agent).proxyEnv, process.env);
+  });
+
+  it('passes proxyEnv to agents when NODE_USE_ENV_PROXY is enabled', async function () {
+    process.env.NODE_USE_ENV_PROXY = '1';
+    const factory = httpAgentFactoryFromOptions({ keepAlive: true });
+
+    const agent = (await factory('https:')) as https.Agent;
+
+    assert.strictEqual(agentOptions(agent).keepAlive, true);
+    assert.strictEqual(agentOptions(agent).proxyEnv, process.env);
+  });
+});
+
 describe('mergeOtlpNodeHttpConfigurationWithDefaults', function () {
   const testDefaults: OtlpNodeHttpConfiguration = {
     url: 'http://default.example.test',