Building an AWS lambda service to return binary data (image) as a response without Access header.

aws-lambda-binary.js

let sh = require("sharp")
var ApiBuilder = require('claudia-api-builder'),
api = module.exports = new ApiBuilder();
var req = require('request').defaults({ encoding: null });
    

module.exports = api;

/* 
    Router to resize the image 
    Parameters :
     1. url = url of the image
     2. w = width 
     3. h = height
*/
api.get('/resize', function (request) {
    let image_url =  request.queryString.url;
    let width = parseInt(request.queryString.w);
    let height = parseInt(request.queryString.h);

    const options = {  
        url: image_url,
        method: 'GET'
    }


    return new Promise(function(resolve,reject){
            req(options,async function (err, res, body) {
                try{
                    resolve(await resize_image(body,width,height));
                }catch(err){
                    reject(err);
                }
                reject(err);
           });
    });

     
},{ success: { contentType: 'image/png', contentHandling: 'CONVERT_TO_BINARY'},"isBase64Encoded": true});



/* Helper functions */

// resizes the image to target width and target height and returns a Promise of image buffer. 
async function resize_image(image,targetWidth,targetHeight){
    return new Promise(async (resolve,reject)=>{
        let image_sh = sh(image);
        image_sh.resize(targetWidth, targetHeight,{
            kernel: sh.kernel.nearest
        })
        .embed()
        .png()  
        .toBuffer()
        .then(data=>resolve(data.toString("base64")))
        .catch(err=>reject(err));
    });
}

Detailed blog post on this can be found here https://medium.com/made-in-madras/building-an-aws-lambda-service-to-return-binary-data-image-as-a-response-without-access-header-d991fb1d7b56