Google OAuth 2.0 with Service account with PHP: "Invalid token format error"

Question

I have created my service account, got the private_key and delegated domain wide authority.

Here is my code trying to authenticate with the service account but getting the same "Invalid token format error":

session_start();
include_once 'google-api-php/vendor/autoload.php';

function getClient() {
$client = new Google_Client();
$client->setApplicationName('theName');
$client->setScopes('https://www.googleapis.com/auth/admin.directory.user.readonly');
$client->setAccessType('offline');
$client->setSubject('[email protected]');
$client->setAuthConfig('private_key.json');

// Load previously authorized credentials from a file.
$credentialsPath = 'private_key.json';
if (file_exists($credentialsPath)) {
    $accessToken = json_decode(file_get_contents($credentialsPath), true);
}
else {
    // Request authorization from the user.
    $authUrl = $client->createAuthUrl();
    printf("Open the following link in your browser:\n%s\n", $authUrl);
    print 'Enter verification code: ';
    $authCode = trim(fgets(STDIN));

    // Exchange authorization code for an access token.
    $accessToken = $client->fetchAccessTokenWithAuthCode($authCode);

    // Store the credentials to disk.
    if(!file_exists(dirname($credentialsPath))) {
      mkdir(dirname($credentialsPath), 0700, true);
    }
    file_put_contents($credentialsPath, json_encode($accessToken));
    printf("Credentials saved to %s\n", $credentialsPath);
}

$client->setAccessToken($accessToken);

// Refresh the token if it's expired.
if ($client->isAccessTokenExpired()) {
    $client->fetchAccessTokenWithRefreshToken($client->getRefreshToken());
    file_put_contents($credentialsPath, json_encode($client->getAccessToken()));
}
return $client;
}

And here is screenshot of what I get from $accessToken just before

$client->setAccessToken($accessToken);

with the error itself:

https://postimg.org/image/ajgan5y27/

Any help will be appreciated. Thanks!

Answer 1

The problem was the outdated google api documentation. Turns out the new version for the "getClient" function needs only this to work in case anyone is having troubles:

function getClient() {
    $client = new Google_Client();
    $client->setAuthConfig('private_key.json');
    $client->setApplicationName('theName');
    $client->setScopes(Google_Service_Sheets::SPREADSHEETS_READONLY);
    return $client;
}

Doesn't need to $client->setAccessToken(); at all...

Good job google... Those are the outdated and unreliable documentation pages I took this code from:

https://developers.google.com/admin-sdk/directory/v1/quickstart/php and https://developers.google.com/api-client-library/php/auth/service-accounts

One more thing: in case you need to play with Google Sheets, you may need to add the account service ID ([email protected]) to the google sheet document you want to extract information from.