upstream sample { 
     server 127.0.0.1:3000; 
     server 127.0.0.1:3001; 
     keepalive 64; 
    } 
     server { 
      listen 80; 
      .... 
      server_name 127.0.0.1; 
      .... 
      location / { 
        proxy_redirect off; 
        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_set_header Host $http_host; 
        proxy_set_header X-NginX-Proxy true; 
        proxy_set_header Connection ""; 
        proxy_http_version 1.1; 
        proxy_pass http://sample; 
      } 
    } 

var http = require('http'); 
var morgan    = require('morgan'); 
 
var server1 = http.createServer(function (req, res) { 
 console.log("Request for: " + req.url + "-- port 3000 "); 
 res.writeHead(200, {'Content-Type': 'text/plain'}); 
 res.end('Hello Node.js\n'); 
}).listen(3000, "127.0.0.1"); 
 
var server2 = http.createServer(function (req, res) { 
 console.log("Request for: " + req.url + "-- port 3001 "); 
 res.writeHead(200, {'Content-Type': 'text/plain'}); 
 res.end('Hello Node.js\n'); 
}).listen(3001, "127.0.0.1"); 
 
server1.once('listening', function() { 
 console.log('Server running at http://127.0.0.1:3000/'); 
}); 
 
server2.once('listening', function() { 
 console.log('Server running at http://127.0.0.1:3001/'); 
}); 

Server running at http://127.0.0.1:3000/ 
Server running at http://127.0.0.1:3001/ 
Request for: /-- port 3001  
Request for: /favicon.ico-- port 3000  
Request for: /favicon.ico-- port 3001  
Request for: /-- port 3000  
Request for: /favicon.ico-- port 3001  
Request for: /favicon.ico-- port 3000  
Request for: /-- port 3001  
Request for: /favicon.ico-- port 3000  
Request for: /favicon.ico-- port 3001  
Request for: /-- port 3000  
Request for: /favicon.ico-- port 3001  
Request for: /favicon.ico-- port 3000