start(port, hostname) {
        this.app = express();
        this.server = http.createServer(this.app);

        this.app.get("/", (req, res) => {
            res.set("Content-Type", "text/plain");
            res.write("Migration is in progress, listening message...\n");
            if (this.response) {
                this.response.write("Disconnected\n");
                this.response.end();
            }
            this.response = res;
            // never ending response
        });

        return new Promise((resolve) => {
            this.server.listen(port, hostname, () => {
                if (hostname) {
                    log.info("migration", `Migration server is running on http://${hostname}:${port}`);
                } else {
                    log.info("migration", `Migration server is running on http://localhost:${port}`);
                }
                resolve();
            });
        });
    }
Start the server
@param {number} port Port
@param {string} hostname Hostname
@returns {Promise<void>}