PHP

Get Google API Access Token using JSON Private Key

See more Google APIs Examples

Demonstrates how to get a Google API access token using a JSON service account private key. Chilkat2 PHP

<?php

use Chilkat2\AuthGoogle;
use Chilkat2\Email;
use Chilkat2\FileAccess;
use Chilkat2\MailMan;
use Chilkat2\Socket;

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// --------------------------------------------------------------------------------
// For a step-by-step guide for setting up your Google Workspace service account,
// see Setup Google Workspace Account for Sending SMTP GMail from a Service Account
// --------------------------------------------------------------------------------

// First load the JSON key into a string.
$fac = new FileAccess();
try {
    $jsonKey = $fac->ReadEntireTextFile('qa_data/googleApi/chilkat25-b4214220e565.json', 'utf-8');

    // A Google service account JSON private key looks like this:

    // {
    //   "type": "service_account",
    //   "project_id": "chilkat25",
    //   "private_key_id": "b4214220f565881e19eeb97c2699bf5a0d1e3e0b",
    //   "private_key": "-----BEGIN PRIVATE KEY-----\nMIIEvQ...NXcM=\n-----END PRIVATE KEY-----\n",
    //   "client_email": "chilkatsvc@chilkat25.iam.gserviceaccount.com",
    //   "client_id": "109122032928932715958",
    //   "auth_uri": "https://accounts.google.com/o/oauth2/auth",
    //   "token_uri": "https://oauth2.googleapis.com/token",
    //   "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
    //   "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/chilkatsvc%40chilkat25.iam.gserviceaccount.com",
    //   "universe_domain": "googleapis.com"
    // }

    $gAuth = new AuthGoogle();
    $gAuth->JsonKey = $jsonKey;

    // Specify a scope.
    $gAuth->Scope = 'https://mail.google.com/';

    // Request an access token that is valid for this many seconds.
    $gAuth->ExpireNumSeconds = 3600;

    // When using a Google Workspace account with Gmail APIs, a service account can impersonate a user
    // via a process called domain-wide delegation — and the "sub" claim in the JWT is what enables this.
    // Domain-wide delegation allows a Google Workspace administrator to authorize a service account to
    // act on behalf of any user in the domain, without user interaction.

    // This is required for server-to-server access to user data — such as reading/sending Gmail from a background service.
    // This is your company email address.
    $gAuth->SubEmailAddress = 'info@chilkat.xyz';

    // Connect to www.googleapis.com using TLS
    $tlsSock = new Socket();
    $tlsSock->Connect('www.googleapis.com', 443, true, 5000);

    // Send the request to obtain the access token.
    $gAuth->ObtainAccessToken($tlsSock);
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

// Examine the access token:
$accessToken = $gAuth->AccessToken;
echo 'Access Token: ', $accessToken, "\n";

// Sample output:
// ya29.a0AW4XtxjGTD67Z8 .... IRw0218

// The access token allows us to send unlimited emails while it's valid. Once it expires, we must obtain and use a new one.

// -----------------------------------------------------------------------
$mailman = new MailMan();

// Set the properties for the GMail SMTP server:
$mailman->SmtpHost = 'smtp.gmail.com';
$mailman->SmtpPort = 587;
$mailman->StartTLS = true;

$mailman->SmtpUsername = 'info@chilkat.xyz';
$mailman->OAuth2AccessToken = $accessToken;

// Create a new email object
$email = new Email();

$email->Subject = 'This is a test';
$email->Body = 'This is a test';
$email->From = 'Chilkat Test <info@chilkat.xyz>';
$email->AddTo('Chilkat Software', 'info@chilkatsoft.com');
// To add more recipients, call AddTo, AddCC, or AddBcc once per recipient.

try {
    $mailman->SendEmail($email);
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

try {
    $mailman->CloseSmtpConnection();
} catch (\Chilkat2\Exception $e) {
    echo "Connection to SMTP server not closed cleanly.\n";
}

echo "Successfully sent email using Gmail with a service account key.\n";