From 169379359c1c61761c041974999c1187ea386feb Mon Sep 17 00:00:00 2001
From: Martin Ivanov <martinivanov@users.noreply.github.com>
Date: Fri, 4 Nov 2022 16:17:21 +0200
Subject: [PATCH] Change the shutdown procedure to deregister fabio from the
 registry and then shutdown the proxy (#908)

* change shutdown procedure to deregister and then shutdown the proxy

* document proxy.deregistergraceperiod
---
 config/config.go                                |  1 +
 config/load.go                                  |  1 +
 docs/content/ref/proxy.deregistergraceperiod.md | 15 +++++++++++++++
 fabio.properties                                | 11 +++++++++++
 main.go                                         |  8 ++++----
 5 files changed, 32 insertions(+), 4 deletions(-)
 create mode 100644 docs/content/ref/proxy.deregistergraceperiod.md

diff --git a/config/config.go b/config/config.go
index 08d37fe71..b84c7e18e 100644
--- a/config/config.go
+++ b/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
diff --git a/config/load.go b/config/load.go
index fd24d8513..2c37d5e02 100644
--- a/config/load.go
+++ b/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")
diff --git a/docs/content/ref/proxy.deregistergraceperiod.md b/docs/content/ref/proxy.deregistergraceperiod.md
new file mode 100644
index 000000000..ce4a87341
--- /dev/null
+++ b/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
diff --git a/fabio.properties b/fabio.properties
index 852281729..8e717f1c7 100644
--- a/fabio.properties
+++ b/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.
 #
diff --git a/main.go b/main.go
index 0652b921d..8d3caba59 100644
--- a/main.go
+++ b/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)