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An App is the main entry point for your web server. It wraps an HTTP server, manages its lifecycle, and handles graceful shutdown when the process receives a stop signal.

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What an App does

When you create an app with mizu.New(), you get:
ComponentDescription
RouterEmbedded, so you can call app.Get(), app.Post() directly
LoggerRequest logging enabled by default
Panic recoveryCatches panics in handlers, prevents crashes
Graceful shutdownDrains active requests before stopping

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Create an app

Every Mizu project starts by creating an App: 
package main

import "github.com/go-mizu/mizu"

func main() {
    // Create a new app with default settings
    app := mizu.New()

    // Define a route - App embeds Router, so this works directly
    app.Get("/", func(c *mizu.Ctx) error {
        return c.Text(200, "Hello, Mizu!")
    })

    // Start the HTTP server on port 3000
    // This blocks until you press Ctrl+C
    app.Listen(":3000")
}
When this runs:
  1. mizu.New() creates an app with a router and default logger
  2. app.Get("/", ...) registers a handler for GET requests to ”/”
  3. app.Listen(":3000") starts the HTTP server
The terminal shows startup logs: 
INFO server starting addr=:3000 pid=12345 go_version=go1.22

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Starting the server

Mizu provides three ways to start your server: 
// 1. Listen on a TCP address (most common)
app.Listen(":3000")

// 2. Listen with TLS (HTTPS)
app.ListenTLS(":443", "cert.pem", "key.pem")

// 3. Use an existing listener (advanced)
listener, _ := net.Listen("tcp", ":3000")
app.Serve(listener)
All three methods block until the server stops. They also handle graceful shutdown when the process receives SIGINT (Ctrl+C) or SIGTERM.

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Configuration

Configure the app by setting fields after creation: 
app := mizu.New()

// Shutdown timeout: how long to wait for active requests
// Default: 15 seconds
app.ShutdownTimeout = 30 * time.Second
FieldDefaultDescription
ShutdownTimeout15 secondsMaximum time to wait for active requests to complete during shutdown

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Graceful shutdown

When your app receives a stop signal (SIGINT or SIGTERM):
  1. New connections refused - The server stops accepting new connections
  2. Active requests complete - Running requests continue until finished (up to ShutdownTimeout)
  3. Clean exit - Server exits with success status
This prevents dropped connections during deployments. Your load balancer can redirect traffic while the old instance drains. 
INFO shutdown initiated
INFO server stopped gracefully duration=1.234s
If requests don’t finish within ShutdownTimeout, they’re terminated.

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Health check endpoints

Mizu provides two health check handlers for load balancers and orchestrators like Kubernetes: 
app := mizu.New()

// Liveness probe: is the process alive?
// Always returns 200 OK
http.Handle("/livez", app.LivezHandler())

// Readiness probe: can it handle traffic?
// Returns 200 normally, 503 during shutdown
http.Handle("/readyz", app.ReadyzHandler())

app.Listen(":3000")
EndpointNormalDuring Shutdown
/livez200 OK200 OK
/readyz200 OK503 Service Unavailable
How they differ:
  • Liveness (/livez): “Is the process running?” Used by Kubernetes to decide if the pod should be restarted
  • Readiness (/readyz): “Can it handle traffic?” Used by load balancers to route traffic
During graceful shutdown, /readyz returns 503 so load balancers stop sending new traffic, while /livez continues returning 200 so the pod isn’t killed prematurely.

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Access the underlying server

For advanced configuration, access the http.Server instance: 
app := mizu.New()

// Configure routes...
app.Get("/", handler)

// Access the server (available after calling Listen/ListenTLS/Serve)
// Can be used to configure TLSConfig, ConnState callbacks, etc.
srv := app.Server()

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Complete example

package main

import (
    "net/http"
    "time"

    "github.com/go-mizu/mizu"
)

func main() {
    app := mizu.New()

    // Configure shutdown timeout
    app.ShutdownTimeout = 30 * time.Second

    // Health check endpoints
    http.Handle("/livez", app.LivezHandler())
    http.Handle("/readyz", app.ReadyzHandler())

    // Your API routes
    app.Get("/", func(c *mizu.Ctx) error {
        return c.JSON(200, map[string]string{"status": "ok"})
    })

    app.Group("/api", func(r *mizu.Router) {
        r.Get("/users", listUsers)
        r.Post("/users", createUser)
    })

    // Set error handler
    app.ErrorHandler(func(c *mizu.Ctx, err error) {
        c.Logger().Error("request failed", "error", err)
        c.JSON(500, map[string]string{"error": "internal error"})
    })

    // Start server
    app.Listen(":3000")
}

func listUsers(c *mizu.Ctx) error { return c.JSON(200, []string{}) }
func createUser(c *mizu.Ctx) error { return c.JSON(201, nil) }

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Next steps

Routing

Define URLs and HTTP methods.

Handler

Write request handling logic.