# Graceful Shutdown and Observability — Go (Golang)

Source: https://www.skillbyai.com/en/go/p-shutdown

> Finish in-flight work, then exit.

## Signals, Shutdown, structured logs

Services should stop cleanly when the platform sends SIGTERM (for example during a Kubernetes rollout): stop accepting new connections, let in-flight requests finish with a deadline, close resources, then exit. `signal.NotifyContext` turns signals into a cancelled context, and `http.Server.Shutdown(ctx)` drains connections. Use structured logging with `log/slog`, expose metrics, and enable `net/http/pprof` on an internal port for profiling.

## Graceful shutdown (sketch)

Standard library only; not run here.

```go
ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
defer stop()

go func() {
	if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
		slog.Error("server failed", "err", err)
	}
}()

<-ctx.Done()                                  // wait for SIGTERM / Ctrl+C
shutdownCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
defer cancel()
srv.Shutdown(shutdownCtx)                     // finish in-flight requests
slog.Info("stopped cleanly")
```

## Use slog for structured logs

log/slog writes key-value or JSON logs that log systems can search and aggregate.

**Quiz:** What does http.Server.Shutdown do?

- [ ] Restarts the server
- [ ] Kills all connections immediately
- [x] Stops accepting new connections and waits for in-flight requests to finish
- [ ] Deletes log files

*Answer:* Stops accepting new connections and waits for in-flight requests to finish. Graceful draining.