Connect to Google API in PHP

googleapiClient.php

<?php 

$scope = 'https://www.googleapis.com/auth/analytics.readonly';
$jsonKeyFilePath = '../config/client_secrets.json';

$client = new \Google_Client();
$client->setScopes([$scope]);
$client->setAuthConfigFile($jsonKeyFilePath);
$client->useApplicationDefaultCredentials();
$client->fetchAccessTokenWithAssertion();