feat(vite): enable watch mode for preview

docs/generated/packages/vite/executors/build.json

@@ -78,6 +78,11 @@
       "force": {
         "description": "Force the optimizer to ignore the cache and re-bundle",
         "type": "boolean"
+      },
+      "watch": {
+        "description": "Enable re-building when files change.",
+        "type": "object",
+        "default": null
       }
     },
     "definitions": {},

packages/vite/src/executors/build/build.impl.ts

@@ -10,7 +10,7 @@ import { copyAssets } from '@nrwl/js';
 import { existsSync } from 'fs';
 import { resolve } from 'path';
 
-export default async function viteBuildExecutor(
+export default async function* viteBuildExecutor(
   options: ViteBuildExecutorOptions,
   context: ExecutorContext
 ) {
@@ -24,7 +24,7 @@ export default async function viteBuildExecutor(
     }
   );
 
-  await runInstance(buildConfig);
+  const watcherOrOutput = await runInstance(buildConfig);
 
   const libraryPackageJson = resolve(projectRoot, 'package.json');
   const rootPackageJson = resolve(context.root, 'package.json');
@@ -49,11 +49,56 @@ export default async function viteBuildExecutor(
     );
   }
 
-  return { success: true };
+  if ('on' in watcherOrOutput) {
+    // watcherOrOutput is a RollupWatcher.
+    // event is a RollupWatcherEvent.
+    const emitter = makeEmitter();
+    let success = true;
+    watcherOrOutput.on('event', (event: any) => {
+      if (event.code === 'START') {
+        success = true;
+      } else if (event.code === 'ERROR') {
+        success = false;
+      } else if (event.code === 'END') {
+        emitter.push({ success });
+      }
+      // result must be closed when present.
+      // see https://rollupjs.org/guide/en/#rollupwatch
+      event.result?.close();
+    });
+    yield* emitter;
+  } else {
+    yield { success: true };
+  }
 }
 
 function runInstance(options: InlineConfig) {
   return build({
     ...options,
   });
 }
+
+/**
+ * Helper to create an async iterator.
+ * Calling push on the returned object emits the value.
+ */
+function makeEmitter() {
+  const events = [];
+  let resolve: (value: unknown) => void | null;
+
+  return {
+    push: (event) => {
+      events.push(event);
+      resolve?.(event);
+      resolve = null;
+    },
+    [Symbol.asyncIterator]: () => ({
+      next: async () => {
+        if (events.length == 0) {
+          await new Promise((r) => (resolve = r));
+        }
+        return { value: events.shift(), done: false };
+      },
+    }),
+  };
+}

packages/vite/src/executors/build/schema.d.ts

@@ -12,4 +12,5 @@ export interface ViteBuildExecutorOptions {
   logLevel?: 'info' | 'warn' | 'error' | 'silent';
   mode?: string;
   ssr?: boolean | string;
+  watch?: object | null;
 }

packages/vite/src/executors/build/schema.json

@@ -118,6 +118,11 @@
     "force": {
       "description": "Force the optimizer to ignore the cache and re-bundle",
       "type": "boolean"
+    },
+    "watch": {
+      "description": "Enable re-building when files change.",
+      "type": "object",
+      "default": null
     }
   },
   "definitions": {},

packages/vite/src/executors/preview-server/preview-server.impl.ts

@@ -1,5 +1,5 @@
 import { ExecutorContext, parseTargetString, runExecutor } from '@nrwl/devkit';
-import { InlineConfig, mergeConfig, preview } from 'vite';
+import { InlineConfig, mergeConfig, preview, PreviewServer } from 'vite';
 import {
   getNxTargetOptions,
   getViteSharedConfig,
@@ -22,20 +22,12 @@ export default async function* vitePreviewServerExecutor(
   // Merge the options from the build and preview-serve targets.
   // The latter takes precedence.
   const mergedOptions = {
+    ...{ watch: {} },
     ...buildTargetOptions,
     ...options,
   };
 
-  // Launch the build target.
-  const target = parseTargetString(options.buildTarget, context.projectGraph);
-  const build = await runExecutor(target, mergedOptions, context);
-  for await (const result of build) {
-    if (!result.success) {
-      return result;
-    }
-  }
-
-  // Launch the server.
+  // Retrieve the server configuration.
   const serverConfig: InlineConfig = mergeConfig(
     getViteSharedConfig(mergedOptions, options.clearScreen, context),
     {
@@ -48,41 +40,67 @@ export default async function* vitePreviewServerExecutor(
     console.warn('WARNING: preview is not meant to be run in production!');
   }
 
-  try {
-    const server = await preview(serverConfig);
-    server.printUrls();
+  let server: PreviewServer | undefined;
 
-    const processOnExit = async () => {
-      const { httpServer } = server;
-      // closeAllConnections was added in Node v18.2.0
-      httpServer.closeAllConnections && httpServer.closeAllConnections();
-      httpServer.close(() => {
-        process.off('SIGINT', processOnExit);
-        process.off('SIGTERM', processOnExit);
-        process.off('exit', processOnExit);
-      });
-    };
+  const processOnExit = async () => {
+    await closeServer(server);
+    process.off('SIGINT', processOnExit);
+    process.off('SIGTERM', processOnExit);
+    process.off('exit', processOnExit);
+  };
+
+  process.on('SIGINT', processOnExit);
+  process.on('SIGTERM', processOnExit);
+  process.on('exit', processOnExit);
 
-    process.on('SIGINT', processOnExit);
-    process.on('SIGTERM', processOnExit);
-    process.on('exit', processOnExit);
+  // Launch the build target.
+  const target = parseTargetString(options.buildTarget, context.projectGraph);
+  const build = await runExecutor(target, mergedOptions, context);
 
-    const resolvedUrls = [
-      ...server.resolvedUrls.local,
-      ...server.resolvedUrls.network,
-    ];
+  for await (const result of build) {
+    if (result.success) {
+      try {
+        if (!server) {
+          server = await preview(serverConfig);
+        }
+        server.printUrls();
+
+        const resolvedUrls = [
+          ...server.resolvedUrls.local,
+          ...server.resolvedUrls.network,
+        ];
 
-    yield {
-      success: true,
-      baseUrl: resolvedUrls[0] ?? '',
-    };
-  } catch (e) {
-    console.error(e);
-    yield {
-      success: false,
-      baseUrl: '',
-    };
+        yield {
+          success: true,
+          baseUrl: resolvedUrls[0] ?? '',
+        };
+      } catch (e) {
+        console.error(e);
+        yield {
+          success: false,
+          baseUrl: '',
+        };
+      }
+    } else {
+      yield {
+        success: false,
+        baseUrl: '',
+      };
+    }
   }
 
   await new Promise(() => {});
 }
+
+function closeServer(server?: PreviewServer): Promise<void> {
+  return new Promise((resolve) => {
+    if (!server) {
+      resolve();
+    } else {
+      const { httpServer } = server;
+      // closeAllConnections was added in Node v18.2.0
+      httpServer.closeAllConnections && httpServer.closeAllConnections();
+      httpServer.close(() => resolve());
+    }
+  });
+}

packages/vite/src/utils/options-utils.ts

@@ -142,6 +142,7 @@ export function getViteBuildOptions(
     manifest: options.manifest,
     ssrManifest: options.ssrManifest,
     ssr: options.ssr,
+    watch: options.watch,
   };
 }