fix(core): clean up stale socket files before listening (#34236)

brettburley · web-flow · commit f5a7ea16062b · 2026-02-10T13:36:34.000-05:00
## Current Behavior When running Nx tasks in CI environments (e.g., Buildkite) where the host's /tmp is mounted to containers, intermittent EADDRINUSE errors occur in PseudoIPCServer.init(). This happens because: 1. PseudoIPCServer doesn't clean up its Unix socket file before calling listen() 2. ForkedProcessTaskRunner.createPseudoTerminal() instantiates PseudoTerminal directly instead of using the createPseudoTerminal() helper, bypassing shutdown callback registration When a new container starts with the same PID as a previous run (PID recycling), it generates the same socket path and hits EADDRINUSE because the stale socket file still exists. ## Expected Behavior No EADDRINUSE errors should occur. The PseudoIPCServer should defensively remove any stale socket file before attempting to listen, similar to how the daemon server handles this. ## Related Issue(s) Fixes #34233
diff --git a/packages/nx/src/tasks-runner/forked-process-task-runner.ts b/packages/nx/src/tasks-runner/forked-process-task-runner.ts
@@ -10,7 +10,11 @@ import { stripIndents } from '../utils/strip-indents';
 import { BatchMessageType } from './batch/batch-messages';
 import { DefaultTasksRunnerOptions } from './default-tasks-runner';
 import { getProcessMetricsService } from './process-metrics-service';
-import { PseudoTerminal, PseudoTtyProcess } from './pseudo-terminal';
+import {
+  createPseudoTerminal as createPseudoTerminalWithShutdown,
+  PseudoTerminal,
+  PseudoTtyProcess,
+} from './pseudo-terminal';
 import { BatchProcess } from './running-tasks/batch-process';
 import {
   NodeChildProcessWithDirectOutput,
@@ -186,7 +190,8 @@ export class ForkedProcessTaskRunner {
   }
 
   private async createPseudoTerminal() {
-    const terminal = new PseudoTerminal(new RustPseudoTerminal());
+    // Use the helper to ensure shutdown callbacks are registered
+    const terminal = createPseudoTerminalWithShutdown(true);
 
     await terminal.init();
 
diff --git a/packages/nx/src/tasks-runner/pseudo-ipc.spec.ts b/packages/nx/src/tasks-runner/pseudo-ipc.spec.ts
@@ -0,0 +1,56 @@
+import { PseudoIPCServer } from './pseudo-ipc';
+import { existsSync, writeFileSync, unlinkSync, mkdirSync } from 'fs';
+import { join } from 'path';
+import { tmpdir } from 'os';
+
+describe('PseudoIPCServer', () => {
+  const testSocketDir = join(tmpdir(), 'nx-pseudo-ipc-test');
+  let socketPath: string;
+
+  beforeAll(() => {
+    try {
+      mkdirSync(testSocketDir, { recursive: true });
+    } catch {}
+  });
+
+  beforeEach(() => {
+    socketPath = join(testSocketDir, `test-${process.pid}-${Date.now()}.sock`);
+  });
+
+  afterEach(() => {
+    try {
+      unlinkSync(socketPath);
+    } catch {}
+  });
+
+  it('should clean up stale socket file before listening', async () => {
+    // Create a fake stale socket file
+    writeFileSync(socketPath, '');
+    expect(existsSync(socketPath)).toBe(true);
+
+    const server = new PseudoIPCServer(socketPath);
+    await server.init();
+
+    // Should have successfully listened (stale file was cleaned up)
+    // The socket file should exist again (created by the server)
+    expect(existsSync(socketPath)).toBe(true);
+
+    server.close();
+  });
+
+  it('should work when no stale socket file exists', async () => {
+    // Ensure no file exists
+    try {
+      unlinkSync(socketPath);
+    } catch {}
+    expect(existsSync(socketPath)).toBe(false);
+
+    const server = new PseudoIPCServer(socketPath);
+    await server.init();
+
+    // Should have successfully listened
+    expect(existsSync(socketPath)).toBe(true);
+
+    server.close();
+  });
+});
diff --git a/packages/nx/src/tasks-runner/pseudo-ipc.ts b/packages/nx/src/tasks-runner/pseudo-ipc.ts
@@ -18,11 +18,26 @@
  */
 
 import { connect, Server, Socket } from 'net';
+import { unlinkSync } from 'fs';
 import {
   consumeMessagesFromSocket,
   MESSAGE_END_SEQ,
 } from '../utils/consume-messages-from-socket';
 import { Serializable } from 'child_process';
+import { isWindows } from '../daemon/socket-utils';
+
+/**
+ * Remove a stale socket file if it exists.
+ * This handles cases where a previous process with the same PID
+ * left behind a socket file (e.g., due to PID recycling in containers).
+ */
+function cleanupSocketFile(path: string): void {
+  if (!isWindows) {
+    try {
+      unlinkSync(path);
+    } catch {}
+  }
+}
 
 export interface PseudoIPCMessage {
   type: 'TO_CHILDREN_FROM_PARENT' | 'TO_PARENT_FROM_CHILDREN' | 'CHILD_READY';
@@ -44,6 +59,8 @@ export class PseudoIPCServer {
 
   init(): Promise<void> {
     return new Promise((res) => {
+      cleanupSocketFile(this.path);
+
       this.server = new Server((socket) => {
         this.sockets.add(socket);
         this.registerChildMessages(socket);
