[Python] Why does my Replit deployment work in Webview but fail to load on the production...

I am deploying a web application on Replit using a Reserved VM deployment. While the app works perfectly in the Replit Webview (on ports like 3000 and 3001), it fails to load on the production domain (e.g., https://my-app.replit.app).

Context:

1. 
   My .replit configuration includes the following:
   
   [deployment]
   run = ["npm", "start"]
   deploymentTarget = "gce"
   
   [[ports]]
   localPort = 80
   externalPort = 3000
   
   [[ports]]
   localPort = 3000
   externalPort = 3001
   
   [[ports]]
   localPort = 3001
   externalPort = 3002
   
   [[ports]]
   localPort = 5173
   externalPort = 80
   exposeLocalhost = true
   
   [[ports]]
   localPort = 8080
   externalPort = 8080
2. 
   My frontend uses Vite, and the vite.config.ts has:
   
   export default defineConfig({
   server: {
   host: '0.0.0.0',
   port: process.env.PORT || 3000,
   proxy: {
   '/api': {
   target: 'http://127.0.0.1:8080',
   changeOrigin: true,
   rewrite: (path) => path.replace(/^\/api/, ''),
   },
   },
   },
   });
3. 
   My backend (Python) runs on port 8080:
   
   app.run(host="0.0.0.0", port=8080)
4. 
   According to Replit's documentation for Reserved VM deployments:
   
   • 
     HTTP requests are sent to external port 80.
     
     
   • 
     The server must listen on 0.0.0.0 (not 127.0.0.1).
     
     
   • 
     Port auto-detection will use the first opened port unless explicitly configured.
     

Issues:

• 
  The app works in development but fails on the production domain.
  
  
• 
  Logs suggest the backend is running, but requests to the production domain do not connect to the app.
  
  
• 
  I suspect an issue with port mapping or traffic routing between frontend and backend
  

What I've tried:

1. 
   Configuring PORT=8080 and host=0.0.0.0 in both frontend and backend.
   
   
2. 
   Explicitly mapping ports in .replit to expose 8080 as 80.
   
   
3. 
   Testing Webview ports (3000, 8080) which work locally.
   

Question:


How can I correctly configure my Replit deployment to ensure the application works on the production domain (https://my-app.replit.app) and properly routes traffic between frontend (Vite) and backend (Python)?

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