How to get client IP address in Azure Functions node.js?

Question

I have an Azure function written on node.js. How could I retrieved an IP address of a client that called the function?

What I've found so far:

1. An answer to the same question, but using C#.

2. It is possible to read it from headers:

   module.exports = function (context, req) {
       var ip = req.headers['x-forwarded-for']    
   }
   

Is it reliable to get the ip this way, since it can be easily changed on the way to the function?

Answer 1

Yes it is reliable, because Azure web server will overwrite x-forwarded-for as it knows it is forwarding from load balancer.

Answer 2

If you're using express, consider setting app.set('trust proxy');

For more information, check the express manual page on 'Express behing proxies'