Devenv: Improve webpack readiness check

2025-11-15 14:46:16 +00:00
parent f7a19be381
commit ae32488285
3 changed files with 127 additions and 6 deletions
@@ -0,0 +1,112 @@
+const http = require('http');
+
+/**
+ * Starts a HTTP server that provides a readiness endpoint indicating the build status.
+ * The server responds with:
+ * - 200 when the build is complete and successful
+ * - 503 when the build is in progress, for both the initial build and subsequent rebuilds when in watch mode
+ * - 500 when the build has failed
+ *
+ * This is used in the devenv/frontend-service Tiltfile to determine when the frontend build is ready.
+ */
+class HttpReadinessPlugin {
+  /**
+   * @param {Object} options
+   * @param {number} options.port
+   * @param {string} [options.host]
+   */
+  constructor(options = {}) {
+    this.port = options.port;
+    this.host = options.host || 'localhost';
+    this.isReady = false;
+    this.server = null;
+    this.hasError = false;
+  }
+
+  /**
+   * @param {import('webpack').Compiler} compiler
+   */
+  apply(compiler) {
+    // Start HTTP server on first compilation
+    compiler.hooks.beforeCompile.tapAsync('HttpReadinessPlugin', (params, callback) => {
+      if (!this.server) {
+        this.startServer();
+      }
+      callback();
+    });
+
+    // Mark as building when compilation starts
+    compiler.hooks.compile.tap('HttpReadinessPlugin', () => {
+      this.isReady = false;
+      this.hasError = false;
+      console.log('[HttpReadinessPlugin] Build started - readiness endpoint returning 503');
+    });
+
+    // Mark as ready when compilation completes successfully
+    compiler.hooks.done.tap('HttpReadinessPlugin', (stats) => {
+      if (stats.hasErrors()) {
+        this.hasError = true;
+        this.isReady = false;
+        console.log('[HttpReadinessPlugin] Build completed with errors - readiness endpoint returning 500');
+      } else {
+        this.isReady = true;
+        this.hasError = false;
+        console.log('[HttpReadinessPlugin] Build completed successfully - readiness endpoint returning 200');
+      }
+    });
+
+    // Mark as error on compilation failure
+    compiler.hooks.failed.tap('HttpReadinessPlugin', () => {
+      this.hasError = true;
+      this.isReady = false;
+      console.log('[HttpReadinessPlugin] Build failed - readiness endpoint returning 500');
+    });
+
+    // Close server on shutdown
+    compiler.hooks.shutdown.tap('HttpReadinessPlugin', () => {
+      this.stopServer();
+    });
+  }
+
+  startServer() {
+    this.server = http.createServer((req, res) => {
+      // Only respond to GET requests
+      if (req.method !== 'GET') {
+        res.writeHead(405, { 'Content-Type': 'text/plain' });
+        res.end('Method Not Allowed');
+        return;
+      }
+
+      // Respond based on build state
+      if (this.isReady) {
+        res.writeHead(200, { 'Content-Type': 'text/plain' });
+        res.end('OK - Build ready');
+      } else if (this.hasError) {
+        res.writeHead(500, { 'Content-Type': 'text/plain' });
+        res.end('Error - Build failed');
+      } else {
+        res.writeHead(503, { 'Content-Type': 'text/plain' });
+        res.end('Service Unavailable - Build in progress');
+      }
+    });
+
+    this.server.listen(this.port, this.host, () => {
+      console.log(`[HttpReadinessPlugin] Readiness server listening on http://${this.host}:${this.port}`);
+    });
+
+    this.server.on('error', (error) => {
+      console.error(`[HttpReadinessPlugin] Server error:`, error);
+    });
+  }
+
+  stopServer() {
+    if (this.server) {
+      this.server.close(() => {
+        console.log('[HttpReadinessPlugin] Readiness server stopped');
+      });
+      this.server = null;
+    }
+  }
+}
+
+module.exports = HttpReadinessPlugin;