Node.js – what’s wrong with this configuration for nginx as reverse proxy for node.js

I have a personal domain running on a VPS. I'd like to setup nginx as a reverse proxy to node.js application, but it's not working. Could anyone look at my configuration and tell me what I'm doing wrong?

Let's assume my domain name is example.com. Basically, I'd like to make it so that when I go to node.example.com, it proxies to the node.js app. I also have blog.example.com and www.example.com setup in nginx.

Here's my nginx configuration for the reverse proxy (blog.example.com, www.example.com setup is omitted):

server {
  listen 80;
  server_name node.example.com;

  access_log /srv/www/example.com/logs/node-access.log;
  error_log /srv/www/example.com/logs/node-error.log;

  location / {
      proxy_pass              http://example.com:3000/;
      proxy_redirect          off;
      proxy_set_header        Host            $host;
      proxy_set_header        X-Real-IP       $remote_addr;
      proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
      client_max_body_size    10m;
      client_body_buffer_size 128k;
      proxy_connect_timeout   90;
      proxy_send_timeout      90;
      proxy_read_timeout      90;
      proxy_buffers           32 4k;
  }
}

And here's my node.js application:

var http = require('http');
http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('Hello World\n');
}).listen(3000, "example.com");

I restarted the nginx server and ran the node.js application. But if I go to node.example.com, it says "node.example.com does not exist or unavailable."

I'm not sure what's wrong with my configuration. I tried various combinations, too.

These are the configurations I have tried:

proxy_pass in nginx           |   hostname in node.js app
http:// localhost:3000/        |   ---.listen(3000, "localhost")
http:// 127.0.0.1:3000/        |   ---.listen(3000, "127.0.0.1")
http:// node.example.com:3000/ |   ---.listen(3000, "node.example.com")

I also tried the following nginx configuration:

upstream nodeapp {
  server 127.0.0.1:3000;
}

server {
   ...
   location / {
     proxy_pass     http:// nodeapp;
     ...
   }
   ...
}

And it doesn't work either. What am I doing wrong? I've searched on the web for a few hours and tried various approaches but they all don't seem to work.

I'd really appreciate if someone can help me out.

Thanks!