Lifecycle Overview
First Things
The entry point for all requests to a Laravel application is the public/index.php file. All requests are directed to this file by your web server (Apache / Nginx) configuration. The index.php file doesn't contain much code. Rather, it is a starting point for loading the rest of the framework.
The index.php file loads the Composer generated autoloader definition, and then retrieves an instance of the Laravel application from bootstrap/app.php script. The first action taken by Laravel itself is to create an instance of the application / service container.
HTTP / Console Kernels
Next, the incoming request is sent to either the HTTP kernel or the
console kernel, depending on the type of request that is entering the
application. These two kernels serve as the central location that all
requests flow through. For now, let's just focus on the HTTP kernel,
which is located in app/Http/Kernel.php.
The HTTP kernel extends the Illuminate\Foundation\Http\Kernel class, which defines an array of bootstrappers that will be run before the request is executed. These bootstrappers configure error handling, configure logging, detect the application environment, and perform other tasks that need to be done before the request is actually handled.
The HTTP kernel also defines a list of HTTP middleware that all requests must pass through before being handled by the application. These middleware handle reading and writing the HTTP session, determining if the application is in maintenance mode, verifying the CSRF token, and more.
The method signature for the HTTP kernel's handle method is quite simple: receive a Request and return a Response.
Think of the Kernel as being a big black box that represents your
entire application. Feed it HTTP requests and it will return HTTP
responses.
Service Providers
One of the most important Kernel bootstrapping actions is loading the service providers for your application. All of the service providers for the application are configured in the config/app.php configuration file's providers array. First, the register method will be called on all providers, then, once all providers have been registered, the boot method will be called.
Service providers are responsible for bootstrapping all of the framework's various components, such as the database, queue, validation, and routing components. Since they bootstrap and configure every feature offered by the framework, service providers are the most important aspect of the entire Laravel bootstrap process.
Dispatch Request
Once the application has been bootstrapped and all service providers have been registered, the Request
will be handed off to the router for dispatching. The router will
dispatch the request to a route or controller, as well as run any route
specific middleware.