API Gateway - Lambda - Lets Encrypt certificate rotation

.well-known-acme-challenge.js

"use strict";

exports.handler = (event, context, callback) => {
    /*
    1.  lets-encrypt certbot
            > ./certbot-auto certonly -a manual --rsa-key-size 2048 -d [domain]
            > 
            >
            >
    2.  paste the challenge string in the context.succeed response below
    3.  API Gateway > [API name] > resources > .well-known > acme-challenge
    4.  create resource > name: [challenge param] path: [challenge param]
    5.  create method > GET > type:lambda > region:[region] > [this lambda name] > save
    6.  select GET method > method response > 200 
            a) add response header 'Content-Type' 
            b) delete response body model
    7.  select GET method > integration response > 200
            a) add header mapping 'Content-Type', value "'text/plain'" (N.B. single quotes!)
            b) delete body mapping template 'application/json'
            c) add body mapping template 'text/plain', set template "$input.path('$')"
            d) save
    8.  Actions > Deploy API 
    9.  check endpoint and content-type
    10. finish certbot verification
    11. API Gateway > Custom Domain Names > [domain]
            a) Backup Certificate > Upload
            b) Rotate
            c) wait
            d) check endpoint cert expiry
    */
    
    context.succeed('[challenge string here]');
};