[build-tools] disable apsd in iOS simulator (#3795)

* [build-tools] Disable apsd in iOS Simulator after boot

* [build-tools] Add unit test for disableApsdAsync

* [build-tools] Use { err } logging convention for apsd warning

* [build-tools] Test apsd disable in start_ios_simulator

Author: gwdp

CHANGELOG.md

@@ -28,6 +28,7 @@ This is the log of notable changes to EAS CLI and related packages.
 ### 🐛 Bug fixes
 
 - [build-tools] Fix `eas/start_ios_simulator` hanging on Xcode 26.4 by writing the readiness screenshot to a temp file instead of `/dev/null`. ([#3794](https://github.com/expo/eas-cli/pull/3794) by [@gwdp](https://github.com/gwdp))
+- [build-tools] Disable `apsd` in the iOS Simulator after boot to stop a push-registration log storm that pegs `diagnosticd` CPU for the lifetime of the Simulator. ([#3795](https://github.com/expo/eas-cli/pull/3795) by [@gwdp](https://github.com/gwdp))
 
 ## [19.1.0](https://github.com/expo/eas-cli/releases/tag/v19.1.0) - 2026-05-25
 

packages/build-tools/src/steps/functions/__tests__/startIosSimulator.test.ts

@@ -0,0 +1,76 @@
+import spawn from '@expo/turtle-spawn';
+
+import { createGlobalContextMock } from '../../../__tests__/utils/context';
+import { createMockLogger } from '../../../__tests__/utils/logger';
+import { IosSimulatorUtils } from '../../../utils/IosSimulatorUtils';
+import { createStartIosSimulatorBuildFunction } from '../startIosSimulator';
+
+jest.mock('@expo/turtle-spawn', () => ({
+  __esModule: true,
+  default: jest.fn(),
+}));
+
+jest.mock('../../../utils/IosSimulatorUtils', () => ({
+  IosSimulatorUtils: {
+    getAvailableDevicesAsync: jest.fn(),
+    getDeviceAsync: jest.fn(),
+    cloneAsync: jest.fn(),
+    startAsync: jest.fn(),
+    waitForReadyAsync: jest.fn(),
+    disableApsdAsync: jest.fn(),
+  },
+}));
+
+const mockedSpawn = jest.mocked(spawn);
+const mockedUtils = jest.mocked(IosSimulatorUtils);
+
+function createStep(callInputs?: Record<string, unknown>) {
+  const logger = createMockLogger();
+  const fn = createStartIosSimulatorBuildFunction();
+  const globalCtx = createGlobalContextMock({ logger });
+  const step = fn.createBuildStepFromFunctionCall(globalCtx, { callInputs });
+  return Object.assign(step, { logger });
+}
+
+describe(createStartIosSimulatorBuildFunction, () => {
+  beforeEach(() => {
+    mockedSpawn.mockResolvedValue({ stdout: '', stderr: '' } as any);
+    mockedUtils.getAvailableDevicesAsync.mockResolvedValue([]);
+    mockedUtils.getDeviceAsync.mockResolvedValue(null);
+    mockedUtils.cloneAsync.mockResolvedValue(undefined);
+    mockedUtils.startAsync.mockResolvedValue({ udid: 'test-udid' as any });
+    mockedUtils.waitForReadyAsync.mockResolvedValue(undefined);
+    mockedUtils.disableApsdAsync.mockResolvedValue(undefined);
+  });
+
+  it('disables apsd on the main device and every clone', async () => {
+    mockedUtils.startAsync
+      .mockResolvedValueOnce({ udid: 'base' as any })
+      .mockResolvedValueOnce({ udid: 'clone-1' as any })
+      .mockResolvedValueOnce({ udid: 'clone-2' as any });
+
+    await createStep({ device_identifier: 'iPhone 15', count: 2 }).executeAsync();
+
+    expect(mockedUtils.disableApsdAsync).toHaveBeenCalledWith({
+      udid: 'base',
+      env: expect.any(Object),
+    });
+    expect(mockedUtils.disableApsdAsync).toHaveBeenCalledWith({
+      udid: 'clone-1',
+      env: expect.any(Object),
+    });
+    expect(mockedUtils.disableApsdAsync).toHaveBeenCalledWith({
+      udid: 'clone-2',
+      env: expect.any(Object),
+    });
+  });
+
+  it('continues when disabling apsd fails', async () => {
+    mockedUtils.disableApsdAsync.mockRejectedValue(new Error('apsd disable failed'));
+
+    await createStep({ device_identifier: 'iPhone 15', count: 2 }).executeAsync();
+
+    // Startup is not aborted: readiness is still awaited for each device.
+    expect(mockedUtils.waitForReadyAsync).toHaveBeenCalled();
+  });
+});

packages/build-tools/src/steps/functions/startIosSimulator.ts

@@ -65,6 +65,12 @@ export function createStartIosSimulatorBuildFunction(): BuildFunction {
         env,
       });
 
+      try {
+        await IosSimulatorUtils.disableApsdAsync({ udid, env });
+      } catch (err) {
+        logger.warn({ err }, 'Failed to disable apsd in the Simulator.');
+      }
+
       await IosSimulatorUtils.waitForReadyAsync({ udid, env });
 
       logger.info('');
@@ -96,6 +102,12 @@ export function createStartIosSimulatorBuildFunction(): BuildFunction {
             env,
           });
 
+          try {
+            await IosSimulatorUtils.disableApsdAsync({ udid: cloneUdid, env });
+          } catch (err) {
+            logger.warn({ err }, 'Failed to disable apsd in the Simulator.');
+          }
+
           await IosSimulatorUtils.waitForReadyAsync({
             udid: cloneUdid,
             env,

packages/build-tools/src/utils/IosSimulatorUtils.ts

@@ -157,6 +157,25 @@ export namespace IosSimulatorUtils {
     );
   }
 
+  export async function disableApsdAsync({
+    udid,
+    env,
+  }: {
+    udid: IosSimulatorUuid;
+    env: NodeJS.ProcessEnv;
+  }): Promise<void> {
+    await spawn(
+      'xcrun',
+      ['simctl', 'spawn', udid, 'launchctl', 'disable', 'system/com.apple.apsd'],
+      { env }
+    );
+    await spawn(
+      'xcrun',
+      ['simctl', 'spawn', udid, 'launchctl', 'bootout', 'system/com.apple.apsd'],
+      { env }
+    );
+  }
+
   export async function collectLogsAsync({
     deviceIdentifier,
     env,

packages/build-tools/src/utils/__tests__/IosSimulatorUtils.test.ts

@@ -41,4 +41,24 @@ describe('IosSimulatorUtils', () => {
       );
     });
   });
+
+  describe(IosSimulatorUtils.disableApsdAsync, () => {
+    it('disables and boots out apsd in the simulator', async () => {
+      await IosSimulatorUtils.disableApsdAsync({
+        udid: 'test-udid' as any,
+        env: process.env,
+      });
+
+      expect(mockedSpawn).toHaveBeenCalledWith(
+        'xcrun',
+        ['simctl', 'spawn', 'test-udid', 'launchctl', 'disable', 'system/com.apple.apsd'],
+        { env: process.env }
+      );
+      expect(mockedSpawn).toHaveBeenCalledWith(
+        'xcrun',
+        ['simctl', 'spawn', 'test-udid', 'launchctl', 'bootout', 'system/com.apple.apsd'],
+        { env: process.env }
+      );
+    });
+  });
 });