# Application Startup Configuration

When the application starts up, we often need to set up some initialization logic. The application bootstraps with those specific configurations. It is in a healthy state and be able to take external service requests after those configurations successfully applied. Otherwise, it failed.

The framework starts with a file called app.js that executes the application initialization logic, if present, and it returns a function.

For example, we need to load a list of national cities from the remote server during application startup for subsequent use in the controller:

// app.js
module.exports = app => {
app.beforeStart(async () => {
// The lifecycle method runs before the application bootstraps
app.cities = await app.curl('http://example.com/city.json', {
method: 'GET',
dataType: 'json',
});

// also could create an anonymous context to call Service
// const ctx = app.createAnonymousContext();
// app.cities = await ctx.service.cities.load();
});
};

cities attribute has attached on the global app. It can be accessed in the controller,

// app/controller/home.js
class HomeController extends Controller {
async index() {
// 'app.cities' is loaded, and you can access it by 'this.ctx.app.cities'
}
}

Note: When the framework executes the lifecycle method beforeStart, do not run time-consuming operation. The framework enables a Timeout setting by default when it starts up.