AWS Lambda Re-Use DB Connection

1'use strict';
2
3const mysql = require('mysql'); // require mysql
4
5// If 'client' variable doesn't exist
6if (typeof client === 'undefined') {
7  // Connect to the MySQL database
8  var client = mysql.createConnection({
9    // your connection info
10  });
11
12  client.connect()
13}
14
15module.exports.handler = (event, context, callback) => {
16  // This will allow us to freeze open connections to a database
17  context.callbackWaitsForEmptyEventLoop = false;
18
19  client.query('SELECT * FROM `books`', function (error, results) {
20    callback(null, results)
21  });
22}