ctx_timeouts.go

func main() {
	// creating parent context
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	// this is for graceful shutdown
	exit := make(chan os.Signal, 1)
	signal.Notify(exit, os.Interrupt, syscall.SIGTERM)

	for {
		select {
		case <-exit:
			cancel()
			fmt.Println("shutting down gracefully.")
		case <-ctx.Done():
			// listens for parent context cancellation
			fmt.Println("parent context is cancelled.")
			os.Exit(0)
		default:
			// calls our service check every one second.
			time.Sleep(1 * time.Second)
			if serviceHealthCheck(ctx, "https://google.com") {
				fmt.Println("Service OK")
			} else {
				fmt.Println("Service Fail")
			}
		}
	}
}

// serviceHealthCheck is a very dumb healthcheck which
// takes an url and return true if able to get the url
// in the specified context timout duration else false.
func serviceHealthCheck(ctx context.Context, url string) bool {
	status := make(chan bool, 1)

	// create a new context with parent ctx and provide timeout duration
	// you can also use context.WithDeadline as follows.
	//ctx, cancel := context.WithDeadline(ctx, time.Now().Add(700*time.Millisecond))
	ctx, cancel := context.WithTimeout(ctx, 700*time.Millisecond)

	defer cancel()

	// dummy implementation of service health check
	go func(url string) {
		client := http.Client{}
		if _, err := client.Get(url); err != nil {
			status <- false
		}
		status <- true
	}(url)

	select {
	case s := <-status:
		return s
	case <-ctx.Done():
		fmt.Println("request timeout")
		return false
	}
}