open-telemetry · overbalance · Jan 16, 2026 · Jan 15, 2026 · Jan 15, 2026 · trentm
@@ -16,6 +16,8 @@ For notes on migrating to 2.x / 0.200.x see [the upgrade guide](doc/upgrade-to-2
 
 ### :bug: Bug Fixes
 
+* refactor(resources): use runtime check for default service name [#6257](https://github.com/open-telemetry/opentelemetry-js/pull/6257) @overbalance
+
 ### :books: Documentation
 
 ### :house: Internal

@@ -0,0 +1,2 @@
+package-lock=false
+install-links=false
@@ -0,0 +1,7 @@
+export default function RootLayout({ children }) {
+  return (
+    <html lang="en">
+      <body>{children}</body>
+    </html>
+  );
+}
@@ -0,0 +1,3 @@
+export default function Home() {
+  return <h1>OTel Edge Runtime Test</h1>;
+}
@@ -0,0 +1,11 @@
+import { defaultServiceName } from '@opentelemetry/resources';
+
+export function middleware(request) {
+  const serviceName = defaultServiceName();
+  console.log('Service name:', serviceName);
+  return Response.next();
+}
+
+export const config = {
+  matcher: '/api/:path*',
+};
@@ -0,0 +1,19 @@
+/** @type {import('next').NextConfig} */
+const nextConfig = {
+  webpack: (config, { dev }) => {
+    // Treat warnings as errors
+    config.plugins.push({
+      apply: compiler => {
+        compiler.hooks.done.tap('FailOnWarnings', stats => {
+          if (stats.compilation.warnings.length > 0) {
+            console.error(stats.compilation.warnings.join('\n'));
+            throw new Error('Webpack build has warnings');
+          }
+        });
+      },
+    });
+    return config;
+  },
+};
+
+export default nextConfig;
@@ -0,0 +1,15 @@
+{
+  "name": "nextjs-15-edge-bundle-test",
+  "type": "module",
+  "private": true,
+  "scripts": {
+    "build": "rm -rf .next && next build",
+    "test:bundle": "npm i && npm run build"
+  },
+  "dependencies": {
+    "@opentelemetry/resources": "file:../../../packages/opentelemetry-resources",
+    "next": "^15",
+    "react": "^18",
+    "react-dom": "^18"
+  }
+}
@@ -0,0 +1,3 @@
+{
+  "name": "nextjs-15-edge-bundle-test"
+}
@@ -0,0 +1,2 @@
+package-lock=false
+install-links=false
@@ -0,0 +1,10 @@
+import { defaultServiceName } from '@opentelemetry/resources';
+
+export const runtime = 'edge';
+
+export function GET(request) {
+  const serviceName = defaultServiceName();
+  return new Response(JSON.stringify({ serviceName }), {
+    headers: { 'Content-Type': 'application/json' },
+  });
+}
@@ -0,0 +1,7 @@
+export default function RootLayout({ children }) {
+  return (
+    <html lang="en">
+      <body>{children}</body>
+    </html>
+  );
+}
@@ -0,0 +1,3 @@
+export default function Home() {
+  return <h1>OTel Edge Runtime Test</h1>;
+}
@@ -0,0 +1,4 @@
+/** @type {import('next').NextConfig} */
+const nextConfig = {};
+
+export default nextConfig;
@@ -0,0 +1,22 @@
+/**
+ * Next.js 16+ uses Turbopack, which lacks callbacks for build errors or warnings.
+ * This script runs the build and fails if Turbopack reports any warnings.
+ */
+import { execSync } from 'node:child_process';
+import path from 'node:path';
+
+const testDir = path.dirname(new URL(import.meta.url).pathname);
+
+// Install dependencies and run build, capturing both stdout and stderr
+const output = execSync('npm run build 2>&1', {
+  cwd: testDir,
+  encoding: 'utf-8',
+});
+
+const hasWarning = /Turbopack build encountered/.test(output);
+if (hasWarning) {
+  console.error('Build produced warnings:\n', output);
+  process.exit(1);
+}
+
+console.log('Build completed without warnings');
@@ -0,0 +1,15 @@
+{
+  "name": "nextjs-16-edge-bundle-test",
+  "type": "module",
+  "private": true,
+  "scripts": {
+    "build": "rm -rf .next && next build",
+    "test:bundle": "npm i && npx tsx next.test.ts"
+  },
+  "dependencies": {
+    "@opentelemetry/resources": "file:../../../packages/opentelemetry-resources",
+    "next": "^16",
+    "react": "^19",
+    "react-dom": "^19"
+  }
+}
@@ -0,0 +1,3 @@
+{
+  "name": "nextjs-16-edge-bundle-test"
+}
@@ -14,15 +14,26 @@
  * limitations under the License.
  */
 
-// Check if we are in a Node.js environment and if so, use the process.argv0 property
-// to determine the default service name
-const DEFAULT_SERVICE_NAME =
-  typeof process === 'object' &&
-  typeof process.argv0 === 'string' &&
-  process.argv0.length > 0
-    ? `unknown_service:${process.argv0}`
-    : 'unknown_service';
+let serviceName: string | undefined;
 
+/**
+ * Returns the default service name for OpenTelemetry resources.
+ * In Node.js environments, returns "unknown_service:<process.argv0>".
+ * In browser/edge environments, returns "unknown_service".
+ */
 export function defaultServiceName(): string {
-  return DEFAULT_SERVICE_NAME;
+  if (serviceName === undefined) {
+    try {
+      const argv0 = globalThis.process.argv0;
+      serviceName = argv0 ? `unknown_service:${argv0}` : 'unknown_service';
+    } catch {
+      serviceName = 'unknown_service';
+    }
+  }
+  return serviceName;
+}
+
+/** @internal For testing purposes only */
+export function _clearDefaultServiceNameCache(): void {
+  serviceName = undefined;
 }
@@ -26,6 +26,7 @@ import * as assert from 'assert';
 import * as sinon from 'sinon';
 import { describeBrowser, describeNode } from './util';
 import { defaultResource, emptyResource, resourceFromAttributes } from '../src';
+import { _clearDefaultServiceNameCache } from '../src/default-service-name';
 import * as EventEmitter from 'events';
 
 describe('Resource', () => {
@@ -43,6 +44,8 @@ describe('Resource', () => {
     'k8s.io/location': 'location1',
   });
 
+  beforeEach(() => _clearDefaultServiceNameCache());
+
   it('should return merged resource', () => {
     const expectedResource = resourceFromAttributes({
       'k8s.io/container/name': 'c1',

@@ -15,32 +15,49 @@
  */
 
 import * as assert from 'assert';
-import { defaultServiceName } from '../src/default-service-name';
-
-const isNode = typeof process === 'object' && typeof process.argv0 === 'string';
+import {
+  _clearDefaultServiceNameCache,
+  defaultServiceName,
+} from '../src/default-service-name';
+import { describeNode } from './util';
 
 describe('defaultServiceName', () => {
+  const originalProcess = globalThis.process;
+
+  beforeEach(() => _clearDefaultServiceNameCache());
+  afterEach(() => {
+    globalThis.process = originalProcess;
+  });
+
   it('returns unknown_service prefix', () => {
     const serviceName = defaultServiceName();
     assert.ok(serviceName.startsWith('unknown_service'));
   });
 
-  if (isNode) {
+  it('returns consistent value on multiple calls', () => {
+    const serviceName1 = defaultServiceName();
+    const serviceName2 = defaultServiceName();
+    assert.strictEqual(serviceName1, serviceName2);
+  });
+
+  describeNode('defaultServiceName', () => {
     it('includes process.argv0 in Node.js', () => {
       const serviceName = defaultServiceName();
-      assert.ok(serviceName.startsWith('unknown_service:'));
-      assert.ok(serviceName.length > 'unknown_service:'.length);
+      assert.match(serviceName, /^unknown_service:.+/);
     });
-  } else {
-    it('returns plain unknown_service in browser', () => {
+
+    it('returns plain unknown_service when process is not an object', () => {
+      // @ts-expect-error redefining process for testing
+      globalThis.process = undefined;
       const serviceName = defaultServiceName();
       assert.strictEqual(serviceName, 'unknown_service');
     });
-  }
 
-  it('returns consistent value on multiple calls', () => {
-    const serviceName1 = defaultServiceName();
-    const serviceName2 = defaultServiceName();
-    assert.strictEqual(serviceName1, serviceName2);
+    it('returns plain unknown_service when process is stubbed but empty (edge runtimes)', () => {
+      // @ts-expect-error redefining process for testing
+      globalThis.process = {};
+      const serviceName = defaultServiceName();
+      assert.strictEqual(serviceName, 'unknown_service');
+    });
   });
 });