Sorry, didn't see you reply ;-)
Depends on the app you're building. For a simple RESTful API, 10 lines are enough :
setupApp() {
this.app.use(cors());
this.app.use(bodyParser.json());
this.app.use(bodyParser.urlencoded({extended: false}));
this.app.use(authUser(this));
this.app.use((req, res, next) => {
req.db = this.db;
req.config = this.config;
next();
});