How to get Node JS Express to listen only on localhost

Question

I have an application that I have behind a reverse proxy  I would like for it to only listen to localhost 127 0 0 1   I expected this to work   app listen 3001   localhost     or  app listen 3001   127 0 0 1        but instead I get an error   node js 201     throw e     process nextTick error  or  error  event on first tick             TypeError  Cannot read property  port  of null     at Object  lt anonymous gt    home ctoledo hive-go go js 204 76      at Module  compile  module js 441 26      at Object  js  module js 459 10      at Module load  module js 348 31      at Function  load  module js 308 12      at Array 0  module js 479 10      at EventEmitter  tickCallback  node js 192 40    Running the application without a specifying the hostname works fine  ie   app listen 3001     I am running Node v0 6 14 and express 2 5 5 and have read this google groups discussion and have found this comment in Express application js saying   This method takes the same arguments as node s http Server listen      Thanks for any help

User · Answer

You are having this problem because you are attempting to console log app.address() before the connection has been made. You just have to be sure to console log after the connection is made, i.e. in a callback or after an event signaling that the connection has been made.

Fortunately, the 'listening' event is emitted by the server after the connection is made so just do this:

var express = require('express');
var http = require('http');

var app = express();
var server = http.createServer(app);

app.get('/', function(req, res) {
    res.send("Hello World!");
});

server.listen(3000, 'localhost');
server.on('listening', function() {
    console.log('Express server started on port %s at %s', server.address().port, server.address().address);
});

This works just fine in nodejs v0.6+ and Express v3.0+.

User · Answer

Thanks for the info  think I see the problem  This is a bug in hive-go that only shows up when you add a host  The last lines of it are   app listen 3001   console log      port  d in  s mode   app address   port  app settings env     When you add the host on the first line  it is crashing when it calls app address   port   The problem is the potentially asynchronous nature of  listen    Really it should be doing that console log call inside a callback passed to listen  When you add the host  it tries to do a DNS lookup  which is async  So when that line tries to fetch the address  there isn t one yet because the DNS request is running  so it crashes   Try this   app listen 3001   localhost   function       console log      port  d in  s mode   app address   port  app settings env

[node.js] How to get Node.JS Express to listen only on localhost?

Examples related to node.js

Examples related to express