Preload trampoline binaries to avoid race conditions when lazily downloading during parallel builds

.changeset/preload-trampoline-binaries.md

@@ -0,0 +1,5 @@
+---
+'@shopify/app': patch
+---
+
+Fix `shopify app build` intermittently failing with `ETXTBSY` ("text file busy") when building apps with multiple function extensions on a fresh environment

packages/app/src/cli/services/build.ts

@@ -1,6 +1,6 @@
 import buildWeb from './web.js'
 import {installAppDependencies} from './dependencies.js'
-import {installJavy} from './function/build.js'
+import {installJavy, installTrampolines} from './function/build.js'
 import {AppInterface, Web} from '../models/app/app.js'
 import {Project} from '../models/project/project.js'
 import {renderConcurrent, renderSuccess} from '@shopify/cli-kit/node/ui'
@@ -24,9 +24,11 @@ async function build(options: BuildOptions) {
     env.SHOPIFY_API_KEY = options.apiKey
   }
 
-  // Force the download of the javy binary in advance to avoid later problems,
-  // as it might be done multiple times in parallel. https://github.com/Shopify/cli/issues/2877
-  await installJavy(options.app)
+  // Force the download of binaries in advance to avoid later problems,
+  // as it might be done multiple times in parallel.
+  // javy -> https://github.com/Shopify/cli/issues/2877
+  // trampoline -> ETXTBSY race conditions during parallel Rust builds
+  await Promise.all([installJavy(options.app), installTrampolines(options.app)])
 
   await renderConcurrent({
     processes: [

packages/app/src/cli/services/deploy/bundle.ts

@@ -1,6 +1,6 @@
 import {AppInterface, AppManifest} from '../../models/app/app.js'
 import {Identifiers} from '../../models/app/identifiers.js'
-import {installJavy} from '../function/build.js'
+import {installJavy, installTrampolines} from '../function/build.js'
 import buildWeb from '../web.js'
 import {compressBundle, writeManifestToBundle} from '../bundle.js'
 import {AbortSignal} from '@shopify/cli-kit/node/abort'
@@ -31,10 +31,12 @@ export async function bundleAndBuildExtensions(options: BundleOptions): Promise<
 
   await writeManifestToBundle(options.appManifest, bundleDirectory)
 
-  // Force the download of the javy binary in advance to avoid later problems,
-  // as it might be done multiple times in parallel. https://github.com/Shopify/cli/issues/2877
+  // Force the download of binaries in advance to avoid later problems,
+  // as it might be done multiple times in parallel.
+  // javy -> https://github.com/Shopify/cli/issues/2877
+  // trampoline -> ETXTBSY race conditions during parallel Rust builds
   if (!options.skipBuild) {
-    await installJavy(options.app)
+    await Promise.all([installJavy(options.app), installTrampolines(options.app)])
   }
 
   const webBuildProcesses = options.skipBuild

packages/app/src/cli/services/dev/processes/draftable-extension.ts

@@ -4,7 +4,6 @@ import {ExtensionInstance} from '../../../models/extensions/extension-instance.j
 import {AppInterface} from '../../../models/app/app.js'
 import {PartnersAppForIdentifierMatching, ensureDeploymentIdsPresence} from '../../context/identifiers.js'
 import {getAppIdentifiers} from '../../../models/app/identifiers.js'
-import {installJavy} from '../../function/build.js'
 import {DeveloperPlatformClient} from '../../../utilities/developer-platform-client.js'
 import {AppEvent, AppEventWatcher, EventType} from '../app-events/app-event-watcher.js'
 import {AbortError} from '@shopify/cli-kit/node/error'
@@ -28,10 +27,6 @@ export const pushUpdatesForDraftableExtensions: DevProcessFunction<DraftableExte
   {stderr, stdout},
   {developerPlatformClient, apiKey, remoteExtensionIds: remoteExtensions, localApp: app, appWatcher},
 ) => {
-  // Force the download of the javy binary in advance to avoid later problems,
-  // as it might be done multiple times in parallel. https://github.com/Shopify/cli/issues/2877
-  await installJavy(app)
-
   const draftableExtensions = app.draftableExtensions.map((ext) => ext.handle)
 
   const handleAppEvent = async (event: AppEvent) => {

packages/app/src/cli/services/dev/processes/setup-dev-processes.ts

@@ -21,6 +21,7 @@ import {ApplicationURLs} from '../urls.js'
 import {DeveloperPlatformClient} from '../../../utilities/developer-platform-client.js'
 import {AppEventWatcher} from '../app-events/app-event-watcher.js'
 import {reloadApp} from '../../../models/app/loader.js'
+import {installJavy, installTrampolines} from '../../function/build.js'
 import {getAvailableTCPPort} from '@shopify/cli-kit/node/tcp'
 import {isTruthy} from '@shopify/cli-kit/node/context/utilities'
 import {firstPartyDev} from '@shopify/cli-kit/node/context/local'
@@ -97,6 +98,13 @@ export async function setupDevProcesses({
 
   // At this point, the toml file has changed, we need to reload the app before actually starting dev
   const reloadedApp = await reloadApp(localApp)
+
+  // Force the download of binaries in advance to avoid later problems,
+  // as it might be done multiple times in parallel.
+  // javy -> https://github.com/Shopify/cli/issues/2877
+  // trampoline -> ETXTBSY race conditions during parallel Rust builds
+  await Promise.all([installJavy(reloadedApp), installTrampolines(reloadedApp)])
+
   const appWatcher = new AppEventWatcher(reloadedApp, network.proxyUrl)
 
   // Decide on the appropriate preview URL for a session with these processes

packages/app/src/cli/services/function/build.test.ts

@@ -7,11 +7,13 @@ import {
   runWasmOpt,
   runTrampoline,
   buildJSFunction,
+  installTrampolines,
 } from './build.js'
 import {
   javyBinary,
   javyPluginBinary,
   wasmOptBinary,
+  downloadBinary,
   trampolineBinary,
   PREFERRED_FUNCTION_RUNNER_VERSION,
   PREFERRED_JAVY_VERSION,
@@ -455,6 +457,44 @@ describe('runTrampoline', () => {
   })
 })
 
+describe('installTrampolines', () => {
+  test('downloads both trampoline versions when app has function extensions', async () => {
+    // Given
+    vi.mocked(downloadBinary).mockResolvedValue(undefined)
+    const functionExtension = await testFunctionExtension()
+    const appWithFunctions = testApp({allExtensions: [functionExtension]})
+
+    // When
+    await installTrampolines(appWithFunctions)
+
+    // Then
+    expect(downloadBinary).toHaveBeenCalledWith(trampolineBinary(V1_TRAMPOLINE_VERSION))
+    expect(downloadBinary).toHaveBeenCalledWith(trampolineBinary(V2_TRAMPOLINE_VERSION))
+  })
+
+  test('does not download trampolines when app has no function extensions', async () => {
+    // Given
+    const appWithoutFunctions = testApp({allExtensions: []})
+    vi.mocked(downloadBinary).mockClear()
+
+    // When
+    await installTrampolines(appWithoutFunctions)
+
+    // Then
+    expect(downloadBinary).not.toHaveBeenCalled()
+  })
+
+  test('swallows download errors for unsupported platform/arch combos', async () => {
+    // Given
+    vi.mocked(downloadBinary).mockRejectedValue(new Error('Unsupported platform/architecture combination'))
+    const functionExtension = await testFunctionExtension()
+    const appWithFunctions = testApp({allExtensions: [functionExtension]})
+
+    // When / Then — should not throw
+    await expect(installTrampolines(appWithFunctions)).resolves.toBeUndefined()
+  })
+})
+
 describe('ExportJavyBuilder', () => {
   const exports = ['foo-bar', 'foo-baz']
   const builder = new ExportJavyBuilder(exports)

packages/app/src/cli/services/function/build.ts

@@ -379,6 +379,22 @@ export async function installJavy(app: AppInterface) {
   await Promise.all(downloadPromises)
 }
 
+export async function installTrampolines(app: AppInterface) {
+  const hasFunctionExtensions = app.allExtensions.some((ext) => ext.features.includes('function'))
+  if (!hasFunctionExtensions) {
+    return
+  }
+
+  await Promise.all([
+    downloadBinary(trampolineBinary(V1_TRAMPOLINE_VERSION)).catch((err) => {
+      outputDebug(`Failed to preload trampoline v${V1_TRAMPOLINE_VERSION}: ${err.message}`)
+    }),
+    downloadBinary(trampolineBinary(V2_TRAMPOLINE_VERSION)).catch((err) => {
+      outputDebug(`Failed to preload trampoline v${V2_TRAMPOLINE_VERSION}: ${err.message}`)
+    }),
+  ])
+}
+
 interface JavyBuilder {
   bundle(fun: ExtensionInstance<FunctionConfigType>, options: JSFunctionBuildOptions): Promise<BuildResult>
   compile(