finish

finish

A non-intrusive package adding a graceful shutdown to Go's HTTP server by utilizing http.Server's built-in Shutdown() method.

Quick Start

Assume the following code in a file called simple.go:

package main

import (
	"fmt"
	"log"
	"net/http"
	"time"

	"github.com/pseidemann/finish"
)

func main() {
	http.HandleFunc("/hello", func(w http.ResponseWriter, r *http.Request) {
		time.Sleep(5 * time.Second)
		fmt.Fprintln(w, "world")
	})

	srv := &http.Server{Addr: "localhost:8080"}

	fin := finish.New()
	fin.Add(srv)

	go func() {
		err := srv.ListenAndServe()
		if err != http.ErrServerClosed {
			log.Fatal(err)
		}
	}()

	fin.Wait()
}

Now execute that file:

$ go run simple.go

Do a HTTP GET request:

$ curl localhost:8080/hello

This will print "world" after 5 seconds.

When the server is terminated with pressing Ctrl+C or kill, while /hello is loading, finish will wait until the request was handled, before the server gets killed.

The output will look like this:

2038/01/19 03:14:08 finish: shutdown signal received
2038/01/19 03:14:08 finish: shutting down server ...
2038/01/19 03:14:11 finish: server closed

Customization

Change Timeout

How to change the default timeout of 10 seconds.

package main

import (
	"fmt"
	"log"
	"net/http"
	"time"

	"github.com/pseidemann/finish"
)

func main() {
	http.HandleFunc("/hello", func(w http.ResponseWriter, r *http.Request) {
		time.Sleep(5 * time.Second)
		fmt.Fprintln(w, "world")
	})

	srv := &http.Server{Addr: "localhost:8080"}

	fin := &finish.Finisher{Timeout: 30 * time.Second}
	fin.Add(srv)

	go func() {
		err := srv.ListenAndServe()
		if err != http.ErrServerClosed {
			log.Fatal(err)
		}
	}()

	fin.Wait()
}

In this example the timeout is set to 30 seconds.

Change Logger

How to change the default logger.

package main

import (
	"fmt"
	"log"
	"net/http"
	"time"

	"github.com/pseidemann/finish"
	"github.com/sirupsen/logrus"
)

func main() {
	http.HandleFunc("/hello", func(w http.ResponseWriter, r *http.Request) {
		time.Sleep(5 * time.Second)
		fmt.Fprintln(w, "world")
	})

	srv := &http.Server{Addr: "localhost:8080"}

	fin := &finish.Finisher{Log: logrus.StandardLogger()}
	fin.Add(srv)

	go func() {
		err := srv.ListenAndServe()
		if err != http.ErrServerClosed {
			log.Fatal(err)
		}
	}()

	fin.Wait()
}

In this example, logrus is configured for logging.

Change Signals

How to change the default signals (SIGINT, SIGTERM) which will initiate the shutdown.

package main

import (
	"fmt"
	"log"
	"net/http"
	"syscall"
	"time"

	"github.com/pseidemann/finish"
)

func main() {
	http.HandleFunc("/hello", func(w http.ResponseWriter, r *http.Request) {
		time.Sleep(5 * time.Second)
		fmt.Fprintln(w, "world")
	})

	srv := &http.Server{Addr: "localhost:8080"}

	fin := &finish.Finisher{Signals: append(finish.DefaultSignals, syscall.SIGHUP)}
	fin.Add(srv)

	go func() {
		err := srv.ListenAndServe()
		if err != http.ErrServerClosed {
			log.Fatal(err)
		}
	}()

	fin.Wait()
}

In this example, finish will not only catch the default signals SIGINT and SIGTERM but also the signal SIGHUP.

Full Example

This example uses a custom router httprouter, a different timeout, a custom logger logrus, custom signals, options for Add() and multiple servers.

package main

import (
	"fmt"
	"log"
	"net/http"
	"syscall"
	"time"

	"github.com/julienschmidt/httprouter"
	"github.com/pseidemann/finish"
	"github.com/sirupsen/logrus"
)

func main() {
	routerPub := httprouter.New()
	routerPub.HandlerFunc("GET", "/hello", func(w http.ResponseWriter, r *http.Request) {
		time.Sleep(5 * time.Second)
		fmt.Fprintln(w, "world")
	})

	routerInt := httprouter.New()
	routerInt.HandlerFunc("GET", "/status", func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintln(w, "ok")
	})

	srvPub := &http.Server{Addr: "localhost:8080", Handler: routerPub}
	srvInt := &http.Server{Addr: "localhost:3000", Handler: routerInt}

	fin := &finish.Finisher{
		Timeout: 30 * time.Second,
		Log:     logrus.StandardLogger(),
		Signals: append(finish.DefaultSignals, syscall.SIGHUP),
	}
	fin.Add(srvPub, finish.WithName("public server"))
	fin.Add(srvInt, finish.WithName("internal server"), finish.WithTimeout(5*time.Second))

	go func() {
		logrus.Infof("starting public server at %s", srvPub.Addr)
		err := srvPub.ListenAndServe()
		if err != http.ErrServerClosed {
			log.Fatal(err)
		}
	}()

	go func() {
		logrus.Infof("starting internal server at %s", srvInt.Addr)
		err := srvInt.ListenAndServe()
		if err != http.ErrServerClosed {
			log.Fatal(err)
		}
	}()

	fin.Wait()
}