Disable default domain https://[project-id].appspot.com of Node JS on Google App Engine

Question

I have deployed my Node JS app onto Google Cloud App Engine, and I can successfully add my custom domain for my app.

Let say my custom domain is example.com

Answer 1

After considering GAEfan suggestion, I have made some change on the router logic. If the host name is ended with "appspot.com" and the user agent is included "AppEngine-Google", it will redirect to my custom domain.

router.get('/', function(req, res, next) {
    if(req.get("host").endsWith(GOOGLE_APP_SPOT) && 
        req.get("User-Agent").includes(GOOGLE_USER_AGENT))
    {
        var redirectURL =  url.format({
            protocol: req.protocol,
            host: CUSTOM_DOMAIN,
            pathname: req.originalUrl
        });
        res.redirect(redirectURL);
    }

    res.render('templateName', viewModel);
});