rsvp is a small Go library that makes it easy to run HTTP servers with graceful shutdown functionality.

The API is just two functions: rsvp.ListenAndServe is a drop-in replacement for the standard library http.ListenAndServe function but adds graceful shutdown. For more advanced use cases, rsvp.Run runs an http.Server with graceful shutdown.

The default behavior can be customized with options to configure trigger signals, shutdown timeout and context, TLS and logging.

Installation

go get github.com/jbarham/rsvp

Motivation and Usage

Why does graceful shutdown matter? Because by default, Go HTTP servers will terminate in-flight requests when they're stopped by signals like SIGTERM or SIGINT. This can have unwanted consequences in production systems if those terminated requests were midway through operations such as updating a customer account.

The following sample code demonstrates how rsvp works to gracefully shut down Go HTTP servers without terminating in-flight requests:

package main

import (
	"flag"
	"log"
	"net/http"
	"strconv"
	"time"

	"github.com/jbarham/rsvp"
)

var runGracefully = flag.Bool("graceful", false, "set to shut down gracefully")

func main() {
	flag.Parse()

	http.HandleFunc("GET /{delay}", func(w http.ResponseWriter, r *http.Request) {
		delay, err := strconv.Atoi(r.PathValue("delay"))
		if err != nil {
			w.WriteHeader(http.StatusBadRequest)
			return
		}
		log.Printf("Starting request with %ds delay...", delay)
		time.Sleep(time.Duration(delay) * time.Second)
		log.Print("Finished request")
	})

	if *runGracefully {
		rsvp.ListenAndServe(":8080", nil)
	} else {
		http.ListenAndServe(":8080", nil)
	}
}

Run go run github.com/jbarham/rsvp/demo@latest to start the above HTTP server without graceful shutdown. Load http://localhost:8080/5 to trigger a 5 second request, then stop the server with Ctrl-C and note that the in-flight request is terminated.

Run go run github.com/jbarham/rsvp/demo@latest -graceful to enable graceful shutdown, repeat the above steps and note that the in-flight request is allowed to finish before the server shuts down.

Reference

https://pkg.go.dev/github.com/jbarham/rsvp