Redirect non-HTTPS -> HTTPS in your Express app

app.js

const requireHTTPS = (req, res, next) => {
    if(req.headers['x-forwarded-proto'] !== 'https' && process.env.NODE_ENV === 'production') {
        var secureUrl = "https://" + req.headers['host'] + req.url
        res.writeHead(301, { "Location":  secureUrl })
        res.end()
    }
    next()
}

app.use(requireHTTPS)