Add GCS proxy endpoint for serving report files and MIME type mapping

Author: max-ostapenko

src/controllers/cdnController.js

@@ -0,0 +1,127 @@
+import { Storage } from '@google-cloud/storage';
+
+// Initialize GCS client (uses Application Default Credentials)
+const storage = new Storage();
+
+// MIME type mapping for common file extensions
+const MIME_TYPES = {
+    '.json': 'application/json',
+    '.html': 'text/html',
+    '.css': 'text/css',
+    '.js': 'application/javascript',
+    '.png': 'image/png',
+    '.jpg': 'image/jpeg',
+    '.jpeg': 'image/jpeg',
+    '.gif': 'image/gif',
+    '.svg': 'image/svg+xml',
+    '.webp': 'image/webp',
+    '.ico': 'image/x-icon',
+    '.txt': 'text/plain',
+    '.csv': 'text/csv',
+    '.xml': 'application/xml',
+    '.pdf': 'application/pdf',
+    '.woff': 'font/woff',
+    '.woff2': 'font/woff2',
+    '.ttf': 'font/ttf',
+    '.eot': 'application/vnd.ms-fontobject'
+};
+
+/**
+ * Get MIME type from file path
+ */
+function getMimeType(filePath) {
+    const ext = filePath.substring(filePath.lastIndexOf('.')).toLowerCase();
+    return MIME_TYPES[ext] || 'application/octet-stream';
+}
+
+/**
+ * Proxy endpoint to serve files from private GCS bucket
+ * GET /v1/reports/*
+ *
+ * This serves as a proxy for files stored in gs://httparchive/reports/
+ * The request path after /v1/reports/ maps directly to the GCS object path
+ */
+export const proxyReportsFile = async (req, res, filePath) => {
+    try {
+        const BUCKET_NAME = process.env.GCS_BUCKET_NAME || 'httparchive';
+        const BASE_PATH = process.env.GCS_REPORTS_PATH || 'reports';
+
+        // Validate file path to prevent directory traversal
+        if (filePath.includes('..') || filePath.includes('//')) {
+            res.statusCode = 400;
+            res.end(JSON.stringify({ error: 'Invalid file path' }));
+            return;
+        }
+
+        // Remove leading slash if present
+        const cleanPath = filePath.startsWith('/') ? filePath.slice(1) : filePath;
+
+        // Construct the full GCS object path
+        const objectPath = `${BASE_PATH}/${cleanPath}`;
+
+        // Get the file from GCS
+        const bucket = storage.bucket(BUCKET_NAME);
+        const file = bucket.file(objectPath);
+
+        // Check if file exists
+        const [exists] = await file.exists();
+        if (!exists) {
+            res.statusCode = 404;
+            res.end(JSON.stringify({ error: 'File not found' }));
+            return;
+        }
+
+        // Get file metadata for content type and caching
+        const [metadata] = await file.getMetadata();
+
+        // Determine content type
+        const contentType = metadata.contentType || getMimeType(objectPath);
+
+        // Set response headers
+        res.setHeader('Content-Type', contentType);
+        res.setHeader('Cache-Control', 'public, max-age=86400'); // 24 hours
+        res.setHeader('Access-Control-Allow-Origin', '*');
+        res.setHeader('Access-Control-Allow-Methods', 'GET, OPTIONS');
+        res.setHeader('Access-Control-Allow-Headers', 'Content-Type');
+
+        if (metadata.etag) {
+            res.setHeader('ETag', metadata.etag);
+        }
+        if (metadata.size) {
+            res.setHeader('Content-Length', metadata.size);
+        }
+
+        // Check for conditional request (If-None-Match)
+        const ifNoneMatch = req.headers['if-none-match'];
+        if (ifNoneMatch && metadata.etag && ifNoneMatch === metadata.etag) {
+            res.statusCode = 304;
+            res.end();
+            return;
+        }
+
+        // Stream the file content to the response
+        res.statusCode = 200;
+
+        const readStream = file.createReadStream();
+
+        readStream.on('error', (err) => {
+            console.error('Error streaming file from GCS:', err);
+            if (!res.headersSent) {
+                res.statusCode = 500;
+                res.end(JSON.stringify({ error: 'Failed to read file' }));
+            }
+        });
+
+        readStream.pipe(res);
+
+    } catch (error) {
+        console.error('Error proxying GCS file:', error);
+        if (!res.headersSent) {
+            res.statusCode = 500;
+            res.end(JSON.stringify({
+                error: 'Failed to retrieve file',
+                details: error.message
+            }));
+        }
+    }
+};

src/index.js

@@ -168,6 +168,16 @@ const handleRequest = async (req, res) => {
       const { resetCache } = await import('./utils/controllerHelpers.js');
       const result = resetCache();
       sendJSONResponse(res, result);
+    } else if (pathname.startsWith('/v1/reports/') && req.method === 'GET') {
+      // GCS proxy endpoint for reports files
+      const filePath = pathname.replace('/v1/reports/', '');
+      if (!filePath) {
+        res.statusCode = 400;
+        res.end(JSON.stringify({ error: 'File path required' }));
+        return;
+      }
+      const { proxyReportsFile } = await getController('cdn');
+      await proxyReportsFile(req, res, filePath);
     } else {
       // 404 Not Found
       res.statusCode = 404;

src/package.json

@@ -14,7 +14,8 @@
   },
   "dependencies": {
     "@google-cloud/firestore": "7.11.6",
-    "@google-cloud/functions-framework": "4.0.1"
+    "@google-cloud/functions-framework": "4.0.1",
+    "@google-cloud/storage": "7.14.0"
   },
   "devDependencies": {
     "@jest/transform": "^30.2.0",