function getConnection ()
{
  const options =
  {
    host: "111.11.11.11", //IP address of my Cloud SQL Server
    user: 'root',
    password: 'somePassword',
    database: 'DatabaseName'
  };
  return mysql.createConnection(options);
}

function getConnection ()
{
  const options =
  {
    user: 'root',
    password: 'somePassword',
    database: 'DatabaseName',
    socketPath: '/cloudsql/project-name-123456:europe-west1:sql-instance-name'
  };
  return mysql.createConnection(options);
}

{ [Error: connect ENOENT /cloudsql/project-name-123456:europe-west1:sql-instance-name]
  code: 'ENOENT',
  errno: 'ENOENT',
  syscall: 'connect',
  address: 'cloudsql/project-name-123456:europe-west1:sql-instance-name',
  fatal: true }