Probando Serverless Lambda y Proxy RDS Integration

handler.js

'use strict';

const mysql = require('mysql2');
const connectionParams = {
  host: process.env.DB_HOST,
  user: process.env.DB_USER,
  password: process.env.DB_PASS,
  database: process.env.DB_NAME,
  port: process.env.DB_PORT,
};

let connection;

module.exports.hello = async event => {

  console.log("Starting query ...", connectionParams);
  connection = mysql.createConnection(connectionParams);

  /**
   * Inicializamos los resultados por defecto del return.
   * En primera instancia siempre retornamos error a menos que se demuestre lo contrario
   */
  let queryResult;
  let statusCode = 500;
  let bodyMessage = {};

  /**
   * Siempre retornamos en el finally, lo que hacemos es cambiar el contenido del mensaje.
   */
  try {
    await connect(); //Conectamos
    queryResult = await testQuery(); //Generamos la query
    await connectionEnd(); //Cerramos conexión
    statusCode = 200;
    bodyMessage = queryResult;

  } catch (error) {
    console.log(error);
    statusCode = 500;
    bodyMessage = {
      error: error
    }
  } finally {
    return responseMessage(statusCode, bodyMessage);
  }
};



function responseMessage(statusCode = 200, body = {}) {
  return {
    statusCode: statusCode,
    body: JSON.stringify(body,
      null,
      2
    ),
  };
}


function connect() {
  return new Promise((resolve, reject) => {
    connection.connect(function (err) {
      if (err) {
        console.error('error connecting: ' + err.stack);
        reject(err);
      } else {
        resolve(connect.threadId);
      }
    })
  })
}


function testQuery() {
  return new Promise((resolve, reject) => {
    connection.query("SELECT * FROM user LIMIT 10", function (err, result, fields) {
      if (err) {
        reject(err);
      } else {
        console.log(result);
        resolve(result);
      }
    });
  })
}

function connectionEnd() {
  return new Promise((resolve, reject) => {
    connection.end(function (error, results) {
      // The connection is terminated now 
      console.log("Connection ended");
      if (error) {
        reject(error);
      } else {
        resolve(results);
      }
    });
  })
}