index.js

"use strict";
console.log("Loading hello world function");

exports.handler = async (event) => {
  let name = "you";
  let city = "World";
  let time = "day";
  let day = "";
  let responseCode = 200;
  console.log("request: " + JSON.stringify(event));

  if (event.queryStringParameters && event.queryStringParameters.name) {
    console.log("Received name: " + event.queryStringParameters.name);
    name = event.queryStringParameters.name;
  }

  if (event.queryStringParameters && event.queryStringParameters.city) {
    console.log("Received city: " + event.queryStringParameters.city);
    city = event.queryStringParameters.city;
  }

  if (event.headers && event.headers["day"]) {
    console.log("Received day: " + event.headers.day);
    day = event.headers.day;
  }

  if (event.body) {
    let body = JSON.parse(event.body);
    if (body.time) time = body.time;
  }

  let greeting = `Good ${time}, ${name} of ${city}.`;
  if (day) greeting += ` Happy ${day}!`;

  let responseBody = {
    message: greeting,
    input: event,
  };

  // The output from a Lambda proxy integration must be
  // in the following JSON object. The 'headers' property
  // is for custom response headers in addition to standard
  // ones. The 'body' property  must be a JSON string. For
  // base64-encoded payload, you must also set the 'isBase64Encoded'
  // property to 'true'.
  let response = {
    statusCode: responseCode,
    headers: {
      "x-custom-header": "my custom header value",
    },
    body: JSON.stringify(responseBody),
  };
  console.log("response: " + JSON.stringify(response));
  return response;
};