Node.js

OAuth2 for a GMail using a JSON Service Account Key

See more GMail SMTP/IMAP/POP Examples

This example shows how to obtain an OAuth2 access token for Gmail using a Google Service Account and a JSON private key. Once acquired, the access token can be used to send emails. Remember, upon token expiration, this process needs to be repeated to obtain a new token. Note: This procedure is specific to OAuth2 with Google Service Account keys. Node.js

NODEJS_PRELUDE

function chilkatExample() {

    var success = false;

    //  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.
    var fac = new chilkat.FileAccess();
    var jsonKey = fac.ReadEntireTextFile("qa_data/googleApi/chilkat25-b4214220e565.json","utf-8");
    if (fac.LastMethodSuccess !== true) {
        console.log(fac.LastErrorText);
        return;
    }

    //  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"
    //  }

    var gAuth = new chilkat.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
    var tlsSock = new chilkat.Socket();
    success = tlsSock.Connect("www.googleapis.com",443,true,5000);
    if (success !== true) {
        console.log(tlsSock.LastErrorText);
        return;
    }

    //  Send the request to obtain the access token.
    success = gAuth.ObtainAccessToken(tlsSock);
    if (success !== true) {
        console.log(gAuth.LastErrorText);
        return;
    }

    //  Examine the access token:
    var accessToken = gAuth.AccessToken;
    console.log("Access Token: " + accessToken);

    //  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.

    //  -----------------------------------------------------------------------
    var mailman = new chilkat.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
    var email = new chilkat.Email();

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

    success = mailman.SendEmail(email);
    if (success !== true) {
        console.log(mailman.LastErrorText);
        return;
    }

    success = mailman.CloseSmtpConnection();
    if (success !== true) {
        console.log("Connection to SMTP server not closed cleanly.");
    }

    console.log("Successfully sent email using Gmail with a service account key.");

}

chilkatExample();