The Error

Execution failed due to configuration error: Malformed Lambda proxy response
Wed Oct 26 01:35:28 UTC 2016 : Method completed with status: 502

The Fix

There’s a bunch of stuff you need to check to fix this error.

First, on your routes in Amazon API gateway, make sure you are using LAMDA_PROXY as your Integration Request.

Make sure “Use lambda proxy integration” is checked.

Finally, check your node code for the correct callback object and the correct callback function (you should not be using callback, you should be using context.succeed).

"use strict";

process.env['PATH'] = process.env['PATH'] + ':' + process.env['LAMBDA_TASK_ROOT'];

var handler = function(event, context, callback){
    const query = event.queryStringParameters || {};
    const eventParams = event.body ? JSON.parse(event.body) : {};

    var data = {
       results: [1,2,3],
       success: true       
    };

    // here's the object we need to return
    const res = {
        "statusCode": 200,
        "headers": {},
        "body": JSON.stringify(data)    // body must be returned as a string
    };

    context.succeed(res); // we must use this callback to return to amazon api gateway
    //callback(null, JSON.stringify(res, null, 2)); // this does not work with the api
};

exports.handler = handler;

The Amazon API Gateway callback object is at the very bottom of this page. The documentation sucks, but it’s there.
https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-set-up-simple-proxy.html#api-gateway-simple-proxy-for-lambda-output-format

Good luck.