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Last active Aug 7, 2017
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'use strict';
console.log('Loading function');
exports.handler = (event, context, callback) => {
console.log('Received event:', JSON.stringify(event, null, 2));
See what our origin(what domain is making the request)
//console.log("Origin: " + event.headers.origin);
Open up CORS for two specific domains - a CloudFront URL, and an S3 Storage bucket
This will let the CORS requests go through at the Lambda level and return results
let origin;
if(event.headers.origin == 'INPUT YOUR CLOUDFRONT URL'
|| event.headers.origin == 'INPUT YOUR S3 BUCKET URL')
origin = event.headers.origin
This will send out the response with either a 400 error or a 200 success
Note, also, the headers. We're making sure to pass application/json and allow CORS domain with a varible 'origin'
that we've defined above
const done = (err, res) => callback(null, {
statusCode: err ? '400' : '200',
body: err ? err.message : JSON.stringify(res),
headers: {
'Content-Type': 'application/json',
'Access-Control-Allow-Origin': origin,
If we see an http requst, and it is a GET request, we'll return a simple JSON array. If not, we'll throw an
"unsupported method" and return it as a 400 error
switch (event.httpMethod) {
case 'GET':
done(null, {"messages": [{"id":1,"content":"Hello"},{"id":2,"content":"Serverless"},{"id":3,"content":"AWS"}]});
done(new Error(`Unsupported method "${event.httpMethod}"`));

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@imalchenko imalchenko commented Jul 19, 2017

Sample AWS Lambda function for a serverless app implementation(Written in Node.JS 6.10)

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