Application Bootstrap

Before your application can answer a single request, a lot has to be true: configuration read, a database connected, routes registered, middleware installed. Bootstrapping is that startup sequence, and this page is the order it happens in.

It is worth knowing because the order has consequences. A provider that needs a database connection must run after the one that opens it — get that wrong and it silently finds nothing. Most of the time the generated bootstrap/providers.go already has it right, and you only come here when you are adding something of your own.

The bootstrapping pipeline

It starts in cmd/app/main.go, where each With… call adds one more piece before Run starts listening:

func main() {
    webApp := app.Configure()

    webApp.
        WithRoutes(bootstrap.LoadRoutes()).
        WithHTTPMiddlewares(bootstrap.LoadHTTPMiddlewares()).
        WithMiddlewares(bootstrap.LoadMiddlewares()).
        WithCommands(bootstrap.LoadCommands()).
        WithProviders(bootstrap.LoadProviders()).
        WithErrMap(bootstrap.LoadErrMap()).
    Run()
}

The app.Configure() function creates a new AppEngine instance using functional options:

app.Configure(
    app.WithConfig(config.M{...}),
    app.WithRoutes([]RouteCallback{...}),
    app.WithProviders([]Provider{...}),
)

Boot Order

When Run() is called, the framework initializes in this order:

1. Configuration — Config map is set up from internal/configs/
2. Commands — CLI commands are registered
3. Events — Middleware, routes, commands, and services events fire
4. HTTP Middleware — Global net/http middleware wraps the router
5. Providers — All service providers run their Provide() methods
6. App Middleware — Application-level middleware is registered
7. Routes — Route callbacks register all endpoints
8. ErrMap — Error-to-handler mappings are applied
9. Server Start — The HTTP server begins listening (or CLI executes)

Run Modes

The application detects whether it’s running as a web server or CLI command:

// Returns true if command-line arguments were provided
a.RunningInConsole()

// Check the environment
a.InProduction()
a.Env("development")

If CLI arguments are provided, Run() executes the matching command instead of starting the web server.

Lifecycle Events

The framework fires events at each stage of bootstrapping:

app.ServerStarted            // Fired when the HTTP server starts
app.MiddlewareRegistering    // Before middleware is registered
app.MiddlewareRegistered     // After middleware is registered
app.RoutesRegistering        // Before routes are registered
app.RoutesRegistered         // After routes are registered
app.CommandsRegistering      // Before commands are registered
app.CommandsRegistered       // After commands are registered
app.ServicesRegistering      // Before services are registered
app.ServicesRegistered       // After services are registered

Listen to these events to hook into the application lifecycle (see Event System).