I had the very same problem and then I realized that programming in NodeJS is actually different than Python or Java as its based on JavaScript. I'll try to use simple concepts as there may be a few new folks that would be interested or may come to this question.
Let's look at the following code :
var http = require('http'); // (1)
exports.handler = function(event, context) {
console.log('start request to ' + event.url)
http.get(event.url, // (2)
function(res) { //(3)
console.log("Got response: " + res.statusCode);
context.succeed();
}).on('error', function(e) {
console.log("Got error: " + e.message);
context.done(null, 'FAILURE');
});
console.log('end request to ' + event.url); //(4)
}
Whenever you make a call to a method in http package (1) , it is created as event and this event gets it separate event. The 'get' function (2) is actually the starting point of this separate event.
Now, the function at (3) will be executing in a separate event, and your code will continue it executing path and will straight jump to (4) and finish it off, because there is nothing more to do.
But the event fired at (2) is still executing somewhere and it will take its own sweet time to finish. Pretty bizarre, right ?. Well, No it is not. This is how NodeJS works and its pretty important you wrap your head around this concept. This is the place where JavaScript Promises come to help.
You can read more about JavaScript Promises here. In a nutshell, you would need a JavaScript Promise to keep the execution of code inline and will not spawn new / extra threads.
Most of the common NodeJS packages have a Promised version of their API available, but there are other approaches like BlueBirdJS that address the similar problem.
The code that you had written above can be loosely re-written as follows.
'use strict';
console.log('Loading function');
var rp = require('request-promise');
exports.handler = (event, context, callback) => {
var options = {
uri: 'https://httpbin.org/ip',
method: 'POST',
body: {
},
json: true
};
rp(options).then(function (parsedBody) {
console.log(parsedBody);
})
.catch(function (err) {
// POST failed...
console.log(err);
});
context.done(null);
};
Please note that the above code will not work directly if you will import it in AWS Lambda. For Lambda, you will need to package the modules with the code base too.