(Node.js) Add Custom Claims to JWT for Google Service Account OAuth2

Demonstrates how add custom claims to the JWT when getting a Google API OAuth2 access token using a JSON service account private key.

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOSX, and ARM

var os = require('os');
if (os.platform() == 'win32') {  
    if (os.arch() == 'ia32') {
        var chilkat = require('@chilkat/ck-node21-win-ia32');
    } else {
        var chilkat = require('@chilkat/ck-node21-win64'); 
    }
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node21-arm');
    } else if (os.arch() == 'x86') {
        var chilkat = require('@chilkat/ck-node21-linux32');
    } else {
        var chilkat = require('@chilkat/ck-node21-linux64');
    }
} else if (os.platform() == 'darwin') {
    if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node21-mac-m1');
    } else {
        var chilkat = require('@chilkat/ck-node21-macosx');
    }
}

function chilkatExample() {

    // 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.
    var fac = new chilkat.FileAccess();
    var jsonKey = fac.ReadEntireTextFile("qa_data/googleApi/ChilkatTest-ab2ecd52ef98.json","utf-8");
    if (fac.LastMethodSuccess !== true) {
        console.log(fac.LastErrorText);
        return;
    }

    // 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"
    // 	}

    var gAuth = new chilkat.AuthGoogle();
    gAuth.JsonKey = jsonKey;

    // Choose a scope.
    gAuth.Scope = "https://www.googleapis.com/auth/cloud-platform";

    // Request an access token that is valid for this many seconds.
    gAuth.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.SubEmailAddress = "";

    // --------------------------------------------------------------------------------------
    // To add custom claims, create JSON containing the claims to be added and call AddClaims.
    var moreClaims = new chilkat.JsonObject();
    moreClaims.UpdateString("claimAbc","valueAbc");
    moreClaims.UpdateString("claimXyz","valueXyz");
    // ...
    gAuth.AddClaims(moreClaims);
    // --------------------------------------------------------------------------------------

    // 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.
    var tlsSock = new chilkat.Socket();
    var 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:
    console.log("Access Token: " + gAuth.AccessToken);

}

chilkatExample();