express-http-proxy

import express from 'express'; import proxy from 'express-http-proxy'; import type { Request, Response, NextFunction } from 'express'; const app = express(); const PORT = process.env.PORT || 3000; const PROXY_TARGET = process.env.PROXY_TARGET || 'https://httpbin.org'; // A public test service // Middleware to log all incoming requests before proxying app.use((req: Request, res: Response, next: NextFunction) => { console.log(`Incoming request: ${req.method} ${req.originalUrl}`); next(); }); // Configure the proxy middleware app.use( '/proxy', proxy(PROXY_TARGET, { // Resolve the path for the proxied request proxyReqPathResolver: (req: Request) => { const resolvedPath = req.url.startsWith('/proxy') ? req.url.slice('/proxy'.length) : req.url; console.log(`Resolved proxy path to: ${resolvedPath}`); return resolvedPath; }, // Decorate the request going to the proxy target decorateProxyReq: (proxyReq: any, req: Request) => { console.log(`Adding custom header to proxied request for ${req.path}`); proxyReq.setHeader('X-Proxy-By', 'express-http-proxy-example'); return proxyReq; }, // Decorate the response coming back from the proxy target decorateUserRes: (proxyRes: any, proxyResData: Buffer, userReq: Request, userRes: Response) => { console.log(`Received proxied response status: ${proxyRes.statusCode}`); // Example: modify response data (e.g., inject a footer) const data = proxyResData.toString('utf8'); if (proxyRes.headers['content-type']?.includes('text/html')) { return data.replace('</body>', '<p><i>Proxied via express-http-proxy!</i></p></body>'); } return proxyResData; // Return original data if not HTML }, // Custom error handler for proxy errors proxyErrorHandler: (err: any, res: Response, next: NextFunction) => { console.error('Proxy error:', err); res.status(500).send('Proxy Error: Could not reach target.'); } }) ); // Default route for non-proxied requests app.get('/', (req: Request, res: Response) => { res.send('Hello from the main Express app! Try /proxy/get to use the proxy.'); }); app.listen(PORT, () => { console.log(`Server running on http://localhost:${PORT}`); console.log(`Proxying requests from /proxy to ${PROXY_TARGET}`); console.log(`Try visiting http://localhost:${PORT}/proxy/get for a proxied request.`); });