I can't deploy mern stack application, on node.js server

Question

Hello,I’m trying to deploy, my mern stack app, but it seems that something goes wrong, it is my first website, so can anyone help? My server runs on the following ports: API: localhost://5000Frontend: localhost://3000My server.js file looks like this: const __dirname = path.resolve() app.use('/uploads', express.static(path.join(__dirname, '/uploads'))) if(process.env.NODE_ENV === 'production'){ app.use(express.static(path.join(__dirname, '/frontend/build'))) app.get('*', (req, res) => { res.sendFile(path.resolve(__dirname, 'frontend', 'build', 'index.html')) }) } else { app.get('/', (req, res) => { res.send('App Is Running...') }) } app.use(notFound) app.use(errorHandler) const PORT = process.env.PORT || 5000 app.use((req, res, next) => { res.header("Access-Control-Allow-Origin", "*"); res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept"); next(); }); app.listen(5000, () => { console.log(`Server Is Running In ${process.env.NODE_ENV} Mode On Port ${PORT}`.yellow.bold) }) When I deploy it, it doesn’t deploy successfully. I Bought a node.js server and following the instructions that gave me a digital ocean, When starting the server.js file: root@obstacle-sports-node:~/Obstacle-Sports# pm2 start backend/server.js [PM2] Spawning PM2 daemon with pm2_home=/root/.pm2 [PM2] PM2 Successfully daemonized [PM2] Starting /root/Obstacle-Sports/backend/server.js in fork_mode (1 instance) [PM2] Done. root@obstacle-sports-node:~/Obstacle-Sports# This is my NGINX configuration: root /var/www/html; # Add index.php to the list if you are using PHP index index.html index.htm index.nginx-debian.html; server_name hellonode; location ^~ /assets/ { gzip_static on; expires 12h; add_header Cache-Control public; } location / { proxy_http_version 1.1; proxy_cache_bypass $http_upgrade; proxy_set_header Upgrade $http_upgrade; proxy_set_header Connection 'upgrade'; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header X-Forwarded-Proto $scheme; proxy_pass http://localhost:5000; } but when I am visiting IP address, I get This error 502 Bad Gateway nginx/1.17.10 (Ubuntu) please help :)

Bobby · Answer

Hello,

It appears that Nginx is not able to connect to your Node.js application running on port 5000, hence the 502 Bad Gateway error.

Let’s go through the steps to troubleshoot this issue:

1. Ensure Node.js App is Running:

Firstly, check if your Node.js application is running properly.

You can use the PM2 command pm2 logs to check the logs of your application. If there’s an issue, the logs should give you some indication of what’s going wrong.

pm2 logs

2. Check Listening Port:

Ensure that your Node.js application is listening on the correct port (5000) and that it’s the correct address (0.0.0.0).

In your server.js, where the app starts listening:

app.listen(5000, '0.0.0.0', () => {
    console.log(`Server Is Running In ${process.env.NODE_ENV} Mode  On Port ${PORT}`.yellow.bold)
})

3. Check Firewall Settings:

If your Node.js application is running correctly and is accessible on the server, it could be an issue with firewall settings.

To list all firewall rules:

sudo ufw status

If the firewall is not allowing traffic to port 5000, you can add a rule to allow it:

sudo ufw allow 5000

4. NGINX Configuration:

Your Nginx configuration looks fine, but let’s double-check it anyway. Here’s a basic setup:

server {
    listen 80;
    server_name your_domain.com;

    location / {
        proxy_pass http://localhost:5000;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;
    }

    error_page 502 /502.html;
    location = /502.html {
        root /var/www/html;
        internal;
    }
}