How do I fix Azure App Service Erroring on Port 80?

Question

I'm an Azure App Service noob - I thought it would be pretty much turnkey, but I'm having some port issues it looks like. I've deployed a Node/Express web app to App Service...

When I designate the port to 80 in my Node/Express app and deploy, I can't reach the website. When I go into console and node app.js, I get the error "Error: listen eacces: permission denied 0.0.0.0:80"

When I've used 3000, I get an error that states something else is listening on 3000.

Am I designating incorrect ports? Documentation seems to say that 80 is one of two ports to use with Azure App Service. How do I fix this error or what is the correct port to use?

Thank you

Edit: This running on Windows inside of Azure App Service

score 1 · Answer 1 · answered Apr 17 '23 at 11:51

When I go into console and node app.js, I get the error "Error: listen eacces: permission denied 0.0.0.0:80"

The error indicates that the app is trying to listen on port 80, which requires elevated privileges.

In Azure App Service, the port provided by the PORT environment variable should be used.
This environment variable can be found in the script bin/www in your generated Express app as shown below:

var  port = normalizePort(process.env.PORT || '3000');
app.set('port', port);

To fix the issue, you can change the port in your Node/Express app to use the PORT environment variable. You can also check if there is another process running on port 3000 by running the below command as mentioned in SO:

netstat -ano | findstr :3000------> To check if any process running
tskill <Process_ID>------>to kill the process

If there is another process running on port 3000, you can either stop that process or use a different port in your Node/Express app.

I have created a sample nodejs/expressjs application to check in my environment. Server code:

var  express = require('express');
var  app = express();  
app.get('/', function (req, res) {
res.send('Hello World!');
});

var  port = process.env.PORT || 3000;  
app.listen(port, function () {
console.log('Example app listening on port ' + port + '!');
});

Result:

Running the app in port 80: enter image description here