Merge pull request #317 from DataDog/sdkennedy2/inline-dynamic-imports-shared-config

[APPS] Use manualChunks for self-contained backend function builds

Author: yoannmoinet

packages/plugins/apps/src/vite/build-backend-functions.ts

@@ -28,55 +28,46 @@ export async function buildBackendFunctions(
 ): Promise<string> {
     const outDir = await mkdtemp(path.join(tmpdir(), 'dd-apps-backend-'));
 
-    const virtualEntries: Record<string, string> = {};
-    const input: Record<string, string> = {};
+    log.debug(`Building ${functions.length} backend function(s) via vite.build()`);
 
+    // Build each function individually so that each output is a single
+    // self-contained JS file
     for (const func of functions) {
         const virtualId = `${VIRTUAL_PREFIX}${func.name}`;
-        virtualEntries[virtualId] = generateVirtualEntryContent(
-            func.name,
-            func.entryPath,
-            buildRoot,
-        );
-        input[func.name] = virtualId;
-    }
-
-    log.debug(`Building ${functions.length} backend function(s) via vite.build()`);
+        const virtualContent = generateVirtualEntryContent(func.name, func.entryPath, buildRoot);
 
-    const baseConfig = getBaseBackendBuildConfig(buildRoot, virtualEntries);
+        const baseConfig = getBaseBackendBuildConfig(buildRoot, { [virtualId]: virtualContent });
 
-    // Production: build all functions in one vite.build() call, writing each to
-    // disk as a named file so the archive/upload step can collect them.
-    // Uses multi-entry input (one per function) with \0-prefixed virtual IDs —
-    // the \0 convention prevents other plugins from processing these IDs.
-    const result = await viteBuild({
-        ...baseConfig,
-        build: {
-            ...baseConfig.build,
-            write: true,
-            outDir,
-            emptyOutDir: false,
-            rollupOptions: {
-                ...baseConfig.build.rollupOptions,
-                input,
-                output: { ...baseConfig.build.rollupOptions.output, entryFileNames: '[name].js' },
+        // eslint-disable-next-line no-await-in-loop
+        const result = await viteBuild({
+            ...baseConfig,
+            build: {
+                ...baseConfig.build,
+                write: true,
+                outDir,
+                emptyOutDir: false,
+                rollupOptions: {
+                    ...baseConfig.build.rollupOptions,
+                    input: { [func.name]: virtualId },
+                    output: {
+                        ...baseConfig.build.rollupOptions.output,
+                        entryFileNames: '[name].js',
+                    },
+                },
             },
-        },
-    });
+        });
 
-    const output = Array.isArray(result) ? result[0] : result;
+        const output = Array.isArray(result) ? result[0] : result;
 
-    // viteBuild always returns RolldownOutput here since we don't set build.watch.
-    // RolldownWatcher would only be returned if watch mode were enabled.
-    if ('output' in output) {
-        for (const chunk of output.output) {
-            if (chunk.type !== 'chunk' || !chunk.isEntry) {
-                continue;
+        if ('output' in output) {
+            for (const chunk of output.output) {
+                if (chunk.type !== 'chunk' || !chunk.isEntry) {
+                    continue;
+                }
+                const absolutePath = path.resolve(outDir, chunk.fileName);
+                backendOutputs.set(func.name, absolutePath);
+                log.debug(`Backend function "${func.name}" output: ${absolutePath}`);
             }
-            const funcName = chunk.name;
-            const absolutePath = path.resolve(outDir, chunk.fileName);
-            backendOutputs.set(funcName, absolutePath);
-            log.debug(`Backend function "${funcName}" output: ${absolutePath}`);
         }
     }
 

packages/plugins/apps/src/vite/build-config.ts

@@ -46,7 +46,7 @@ export function getBaseBackendBuildConfig(
             minify: false,
             target: 'esnext',
             rollupOptions: {
-                output: { format: 'es', exports: 'named' },
+                output: { format: 'es', exports: 'named', inlineDynamicImports: true },
                 preserveEntrySignatures: 'exports-only',
                 treeshake: false,
                 onwarn(warning, defaultHandler) {

packages/plugins/apps/src/vite/dev-server.ts

@@ -79,8 +79,6 @@ async function bundleBackendFunction(
     // bundled script to the Datadog API without writing temp files.
     // Uses a plain "virtual:" prefix instead of \0 because Rollup generates
     // empty chunks when \0-prefixed IDs are used as input entries.
-    // inlineDynamicImports collapses everything into one chunk since we only
-    // have a single entry (incompatible with multi-entry builds).
     const result = await viteBuild({
         ...baseConfig,
         build: {
@@ -89,7 +87,7 @@ async function bundleBackendFunction(
             rollupOptions: {
                 ...baseConfig.build.rollupOptions,
                 input: virtualId,
-                output: { ...baseConfig.build.rollupOptions.output, inlineDynamicImports: true },
+                output: baseConfig.build.rollupOptions.output,
             },
         },
     });

packages/plugins/apps/src/vite/index.test.ts

@@ -46,7 +46,7 @@ describe('Backend Functions - getVitePlugin', () => {
         // eslint-disable-next-line @typescript-eslint/no-explicit-any
         await (plugin as any).closeBundle();
 
-        expect(mockViteBuild).toHaveBeenCalledTimes(1);
+        expect(mockViteBuild).toHaveBeenCalledTimes(2);
         expect(defaultOptions.backendOutputs.size).toBe(2);
         expect(defaultOptions.backendOutputs.has('myHandler')).toBe(true);
         expect(defaultOptions.backendOutputs.has('otherFunc')).toBe(true);