(Perl) OAuth2 for a GMail using a JSON Service Account Key

Demonstrates how get an OAuth2 access token for GMail (Google Service Account) using a JSON private key.

After the access token is obtained, it may be used to send email. When the access token expires, a new access token needs to be obtained (using this same procedure).

Note: This is for OAuth2 using Google Service account keys.

Chilkat Perl Downloads Perl Module for Windows, MacOS, Linux, Alpine Linux, Solaris

use chilkat();

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

# First load the JSON key into a string.
$fac = chilkat::CkFileAccess->new();
$jsonKey = $fac->readEntireTextFile("qa_data/googleApi/ChilkatTest-ab2ecd52ef98.json","utf-8");
if ($fac->get_LastMethodSuccess() != 1) {
    print $fac->lastErrorText() . "\r\n";
    exit;
}

# A JSON private key should look like this:

# 	{
# 	  "type": "service_account",
# 	  "project_id": "chilkattest-1350",
# 	  "private_key_id": "fa2e36ee26986eab628b59868af8bec1d1c64c38",
# 	  "private_key": "-----BEGIN PRIVATE KEY-----\nMIIEvgIjFa...28N64N2n1E4FYzBZjSdy\n-----END PRIVATE KEY-----\n",
# 	  "client_email": "598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a@developer.gserviceaccount.com",
# 	  "client_id": "598922945226-00rb0ppfg0snd9jo7bhvd4v17jtj2d3a.apps.googleusercontent.com",
# 	  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
# 	  "token_uri": "https://accounts.google.com/o/oauth2/token",
# 	  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
# 	  "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a%40developer.gserviceaccount.com"
# 	}

$gAuth = chilkat::CkAuthGoogle->new();
$gAuth->put_JsonKey($jsonKey);

# Choose a scope.
$gAuth->put_Scope("https://mail.google.com/");

# Request an access token that is valid for this many seconds.
$gAuth->put_ExpireNumSeconds(3600);

# If the application is requesting delegated access:
# The email address of the user for which the application is requesting delegated access,
# then set the email address here. (Otherwise leave it empty.)
$gAuth->put_SubEmailAddress("");

# Connect to www.googleapis.com using TLS (TLS 1.2 is the default.)
# The Chilkat socket object is used so that the connection can be established
# through proxies or an SSH tunnel if desired.
$tlsSock = chilkat::CkSocket->new();
$success = $tlsSock->Connect("www.googleapis.com",443,1,5000);
if ($success != 1) {
    print $tlsSock->lastErrorText() . "\r\n";
    exit;
}

# Send the request to obtain the access token.
$success = $gAuth->ObtainAccessToken($tlsSock);
if ($success != 1) {
    print $gAuth->lastErrorText() . "\r\n";
    exit;
}

# Examine the access token:
print "Access Token: " . $gAuth->accessToken() . "\r\n";

# Now that we have the access token, it may be used to send email
# while it remains valid.  Once the access token expires, a new access token 
# should be obtained using the same code as above.

# -----------------------------------------------------------------------
$mailman = chilkat::CkMailMan->new();

# Set the properties for the GMail SMTP server:
$mailman->put_SmtpHost("smtp.gmail.com");
$mailman->put_SmtpPort(587);
$mailman->put_StartTLS(1);

$mailman->put_SmtpUsername("YOUR_GOOGLE_APPS_USER_EMAIL_ADDRESS");
$mailman->put_OAuth2AccessToken($gAuth->accessToken());

# Create a new email object
$email = chilkat::CkEmail->new();

$email->put_Subject("This is a test");
$email->put_Body("This is a test");
$email->put_From("YOUR NAME <YOUR_GOOGLE_APPS_USER_EMAIL_ADDRESS>");
$success = $email->AddTo("Chilkat Admin",'admin@chilkatsoft.com');
# To add more recipients, call AddTo, AddCC, or AddBcc once per recipient.

# Call SendEmail to connect to the SMTP server and send.
# The connection (i.e. session) to the SMTP server remains
# open so that subsequent SendEmail calls may use the
# same connection.  
$success = $mailman->SendEmail($email);
if ($success != 1) {
    print $mailman->lastErrorText() . "\r\n";
    exit;
}

# You may close the connection here.  If the connection is kept open, 
# the next call to mailman.SendEmail will continue using the already-established connection
# (and automatically re-connect if needed).
$success = $mailman->CloseSmtpConnection();
if ($success != 1) {
    print "Connection to SMTP server not closed cleanly." . "\r\n";
}

print "Email Sent via GMail using an OAuth2 Service Account Key." . "\r\n";