From 70eb75cfda712751952faf1efe4f9ffc47adeb3e Mon Sep 17 00:00:00 2001
From: Dino Omanovic <d.omanovic@tarent.de>
Date: Fri, 26 May 2017 11:45:56 +0200
Subject: [PATCH] Implemented graceful shutdown via go 1.8 Server.Shutdown(ctx)

---
 README.md       |  1 +
 login/config.go |  3 +++
 main.go         | 27 +++++++++++++++++++--------
 3 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/README.md b/README.md
index 06ad7ba..0debb43 100644
--- a/README.md
+++ b/README.md
@@ -61,6 +61,7 @@ _Note for Caddy users_: Not all parameters are available in Caddy. See the table
 | -success-url      | string      | "/"          | X     | The url to redirect after login                                                      |
 | -template         | string      |              | X     | An alternative template for the login form                                           |
 | -text-logging     | boolean     | true         | -     | Log in text format instead of json                                                   |
+| -grace-period     | go duration | 5s           | -     | Duration to wait after SIGINT/SIGTERM for existing requests. No new requests are accepted.                                                   |
 
 ### Environment Variables
 All of the above Config Options can also be applied as environment variable, where the name is written in the way: `LOGINSRV_OPTION_NAME`.
diff --git a/login/config.go b/login/config.go
index d3e6a01..29e7991 100644
--- a/login/config.go
+++ b/login/config.go
@@ -34,6 +34,7 @@ func DefaultConfig() *Config {
 		CookieHTTPOnly: true,
 		Backends:       Options{},
 		Oauth:          Options{},
+		GracePeriod:    5 * time.Second,
 	}
 }
 
@@ -57,6 +58,7 @@ type Config struct {
 	CookieHTTPOnly bool
 	Backends       Options
 	Oauth          Options
+	GracePeriod    time.Duration
 }
 
 // Options is the configuration structure for oauth and backend provider
@@ -101,6 +103,7 @@ func (c *Config) ConfigureFlagSet(f *flag.FlagSet) {
 	f.StringVar(&c.LogoutURL, "logout-url", c.LogoutURL, "The url or path to redirect after logout")
 	f.StringVar(&c.Template, "template", c.Template, "An alternative template for the login form")
 	f.StringVar(&c.LoginPath, "login-path", c.LoginPath, "The path of the login resource")
+	f.DurationVar(&c.GracePeriod, "grace-period", c.GracePeriod, "Graceful shutdown grace period")
 
 	// the -backends is deprecated, but we support it for backwards compatibility
 	deprecatedBackends := setFunc(func(optsKvList string) error {
diff --git a/main.go b/main.go
index 03e7de6..2add533 100644
--- a/main.go
+++ b/main.go
@@ -6,6 +6,8 @@ import (
 
 	"github.com/tarent/loginsrv/login"
 
+	"context"
+	"fmt"
 	"github.com/tarent/loginsrv/logging"
 	"net/http"
 	"os"
@@ -21,8 +23,6 @@ func main() {
 		exit(nil, err)
 	}
 
-	logShutdownEvent()
-
 	configToLog := *config
 	configToLog.JwtSecret = "..."
 	logging.LifecycleStart(applicationName, configToLog)
@@ -34,15 +34,26 @@ func main() {
 
 	handlerChain := logging.NewLogMiddleware(h)
 
-	exit(nil, http.ListenAndServe(config.Host+":"+config.Port, handlerChain))
-}
+	stop := make(chan os.Signal)
+	signal.Notify(stop, syscall.SIGINT, syscall.SIGTERM)
+
+	port := config.Port
+	if port != "" {
+		port = fmt.Sprintf(":%s", port)
+	}
+
+	httpSrv := &http.Server{Addr: port, Handler: handlerChain}
 
-func logShutdownEvent() {
 	go func() {
-		c := make(chan os.Signal)
-		signal.Notify(c, syscall.SIGINT, syscall.SIGTERM)
-		exit(<-c, nil)
+		if err := httpSrv.ListenAndServe(); err != nil {
+			logging.LifecycleStop(applicationName, nil, err)
+		}
 	}()
+	logging.LifecycleStop(applicationName, <-stop, nil)
+
+	ctx, _ := context.WithTimeout(context.Background(), config.GracePeriod)
+
+	httpSrv.Shutdown(ctx)
 }
 
 var exit = func(signal os.Signal, err error) {