Lifecycle
Understand how Nitro runs and serves incoming requests to your application.
Nitro v3 Alpha docs are a work in progress — expect updates, rough edges, and occasional inaccuracies.
A request can be intercepted and terminated (with or without a response) from any of these layers, in this order:
Route rules
The matching route rule defined in the Nitro config will execute. Note that most of the route rules can alter the response without terminating it (for instance, adding a header).
nitro.config.ts
import { defineNitroConfig } from "nitro/config";
export default defineNitroConfig({
routeRules: {
'/**': { headers: { 'x-nitro': 'first' } }
}
})
Global middleware
Any global middleware defined in the middleware/ directory will be run:
middleware/info.ts
import { defineHandler } from "nitro/h3";
export default defineHandler((event) => {
event.context.info = { name: "Nitro" };
});
Returning from a middleware will close the request and should be avoided when possible.
Server entry
If defined, the server entry handler will be run:
server.ts
import { defineHandler } from "nitro/deps/h3";
export default defineHandler((event) => {
if (event.path === "/") {
return "Home page";
}
});
Think of the server entry as the last global middleware to run.
Routes
At this stage, Nitro will look at defined routes in the routes/ folder to match the incoming request.
routes/api/hello.ts
export default (event) => ({ world: true })
Renderer
If no route is matched, Nitro will look for a renderer handler (defined or auto-detected) to handle the request.