Maybe this extension can help you:
http://www.yiiframework.com/extension/jgoogleapi/
I'm not sure which is the API for sitemaps and what are its methods but that extension would help you Login to google in "Service" mode that won't need your browser to interact with the login.
You should also before create your application in Google console and then create a service account user type for it.
A paste of my config file when using this extension with Google Analytics:
<?php
/*
* How to obtain a Service Account:
* https://developers.google.com/accounts/docs/OAuth2ServiceAccount
*
*
* (403) User does not have any Google Analytics account.
* http://stackoverflow.com/a/13167988/115050
*
*
*/
return array(
'class' => 'ext.JGoogleAPI.JGoogleAPI',
//Default authentication type to be used by the extension
'defaultAuthenticationType'=>'serviceAPI',
//Account type Authentication data
'serviceAPI' => array(
'clientId' => '...',
'clientEmail' => '...',
'keyFilePath' => dirname(__FILE__).'/../extensions/JGoogleAPI/keys/Analytics-a0e8e345f273.p12',
),
/*
//You can define one of the authentication types or both (for a Service Account or Web Application Account)
webAppAPI = array(
'clientId' => 'YOUR_WEB_APPLICATION_CLIENT_ID',
'clientEmail' => 'YOUR_WEB_APPLICATION_CLIENT_EMAIL',
'clientSecret' => 'YOUR_WEB_APPLICATION_CLIENT_SECRET',
'redirectUri' => 'YOUR_WEB_APPLICATION_REDIRECT_URI',
'javascriptOrigins' => 'YOUR_WEB_APPLICATION_JAVASCRIPT_ORIGINS',
),
*/
'simpleApiKey' => 'AIzaSyAx63Ht-0XmuLdp0-j9zVREKNsCyqXgeUA',
//Scopes needed to access the API data defined by authentication type
'scopes' => array(
'serviceAPI' => array(
'drive' => array(
'https://www.googleapis.com/auth/drive.file',
),
'Analytics'=>array(
'https://www.googleapis.com/auth/analytics.readonly',
),
),
'webappAPI' => array(
'drive' => array(
'https://www.googleapis.com/auth/drive.file',
),
),
),
//Use objects when retriving data from api if true or an array if false
'useObjects'=>false,
);
And how I'm using it:
$api = Yii::app()->JGoogleAPI->getService('Analytics');
$api->data_ga->get(...)