get external IP

file.js

var ip = require("ip");
var http = require('http');
var host = "ip-1-2-3-4.ec2.internal"

function getExternalIP(host) {
  if (host.includes('ec2.internal')){
    console.log("This is an EC2 instance. Fetching 'listenIp' via HTTP");
    http.get({'host': 'checkip.amazonaws.com', 'port': 80, 'path': '/'}, function(resp) {
      resp.on('data', function(ip) {
        return ip;
      });
    });
  } else {
    return ip.address();
  }
}

i = getExternalIP(host)
console.log("IP is " + i)

// $ node file.js
// This is an EC2 instance. Fetching 'listenIp' via HTTP
// IP is undefined