Change the shutdown procedure to deregister fabio from the registry a…

…nd then shutdown the proxy (#908)

* change shutdown procedure to deregister and then shutdown the proxy

* document proxy.deregistergraceperiod

config/config.go

@@ -63,6 +63,7 @@ type Proxy struct {
 	NoRouteStatus         int
 	MaxConn               int
 	ShutdownWait          time.Duration
+	DeregisterGracePeriod time.Duration
 	DialTimeout           time.Duration
 	ResponseHeaderTimeout time.Duration
 	KeepAliveTimeout      time.Duration

config/load.go

@@ -138,6 +138,7 @@ func load(cmdline, environ, envprefix []string, props *properties.Properties) (c
 	f.StringVar(&cfg.Proxy.Matcher, "proxy.matcher", defaultConfig.Proxy.Matcher, "path matching algorithm")
 	f.IntVar(&cfg.Proxy.NoRouteStatus, "proxy.noroutestatus", defaultConfig.Proxy.NoRouteStatus, "status code for invalid route. Must be three digits")
 	f.DurationVar(&cfg.Proxy.ShutdownWait, "proxy.shutdownwait", defaultConfig.Proxy.ShutdownWait, "time for graceful shutdown")
+	f.DurationVar(&cfg.Proxy.DeregisterGracePeriod, "proxy.deregistergraceperiod", defaultConfig.Proxy.DeregisterGracePeriod, "time to wait after deregistering from a registry")
 	f.DurationVar(&cfg.Proxy.DialTimeout, "proxy.dialtimeout", defaultConfig.Proxy.DialTimeout, "connection timeout for backend connections")
 	f.DurationVar(&cfg.Proxy.ResponseHeaderTimeout, "proxy.responseheadertimeout", defaultConfig.Proxy.ResponseHeaderTimeout, "response header timeout")
 	f.DurationVar(&cfg.Proxy.KeepAliveTimeout, "proxy.keepalivetimeout", defaultConfig.Proxy.KeepAliveTimeout, "keep-alive timeout")

docs/content/ref/proxy.deregistergraceperiod.md

@@ -0,0 +1,15 @@
+---
+title: "proxy.deregistergraceperiod"
+---
+
+`proxy.deregistergraceperiod` configures the time to wait before 
+shutting down the proxies de-registering from the service registry.
+
+After a signal is caught Fabio will immediately de-register from the
+service registry and wait for `proxy.deregistergraceperiod` letting
+in-flight requests finish after which it will continue with shutting
+down the proxy.
+
+The default is
+
+    proxy.deregistergraceperiod = 0s

fabio.properties

@@ -356,6 +356,17 @@
 #
 # proxy.shutdownwait = 0s
 
+#proxy.deregistergraceperiod configures the time to wait before
+#shutting down the proxies de-registering from the service registry.
+#
+#After a signal is caught Fabio will immediately de-register from the
+#service registry and wait for `proxy.deregistergraceperiod` letting
+#in-flight requests finish after which it will continue with shutting
+#down the proxy.
+#
+#The default is
+#
+#proxy.deregistergraceperiod = 0s
 
 # proxy.responseheadertimeout configures the response header timeout.
 #

main.go

@@ -114,14 +114,14 @@ func main() {
 
 	exit.Listen(func(s os.Signal) {
 		atomic.StoreInt32(&shuttingDown, 1)
+		if registry.Default != nil {
+			registry.Default.DeregisterAll()
+		}
+		time.Sleep(cfg.Proxy.DeregisterGracePeriod)
 		proxy.Shutdown(cfg.Proxy.ShutdownWait)
 		if prof != nil {
 			prof.Stop()
 		}
-		if registry.Default == nil {
-			return
-		}
-		registry.Default.DeregisterAll()
 	})
 
 	metrics, err := metrics.Initialize(&cfg.Metrics)