From 46e162e6a93679a6563156c56a1e223a20dda79a Mon Sep 17 00:00:00 2001
From: emile <emile@vauge.com>
Date: Thu, 8 Oct 2015 17:56:45 +0200
Subject: [PATCH] Add backend throttle duration, resolves
 https://github.com/EmileVauge/traefik/issues/46

---
 configuration.go    | 31 +++++++++++++++++--------------
 docs/index.md       | 10 ++++++++++
 traefik.go          | 29 +++++++++++++++++++++++++++--
 traefik.sample.toml | 10 ++++++++++
 4 files changed, 64 insertions(+), 16 deletions(-)

diff --git a/configuration.go b/configuration.go
index 6a1cb4ace..efdfef429 100644
--- a/configuration.go
+++ b/configuration.go
@@ -3,23 +3,25 @@ package main
 import (
 	"errors"
 	"strings"
+	"time"
 )
 
 type GlobalConfiguration struct {
-	Port              string
-	GraceTimeOut      int64
-	AccessLogsFile    string
-	TraefikLogsFile   string
-	CertFile, KeyFile string
-	LogLevel          string
-	Docker            *DockerProvider
-	File              *FileProvider
-	Web               *WebProvider
-	Marathon          *MarathonProvider
-	Consul            *ConsulProvider
-	Etcd              *EtcdProvider
-	Zookeeper         *ZookepperProvider
-	Boltdb            *BoltDbProvider
+	Port                     string
+	GraceTimeOut             int64
+	AccessLogsFile           string
+	TraefikLogsFile          string
+	CertFile, KeyFile        string
+	LogLevel                 string
+	BackendsThrottleDuration time.Duration
+	Docker                   *DockerProvider
+	File                     *FileProvider
+	Web                      *WebProvider
+	Marathon                 *MarathonProvider
+	Consul                   *ConsulProvider
+	Etcd                     *EtcdProvider
+	Zookeeper                *ZookepperProvider
+	Boltdb                   *BoltDbProvider
 }
 
 func NewGlobalConfiguration() *GlobalConfiguration {
@@ -28,6 +30,7 @@ func NewGlobalConfiguration() *GlobalConfiguration {
 	globalConfiguration.Port = ":80"
 	globalConfiguration.GraceTimeOut = 10
 	globalConfiguration.LogLevel = "ERROR"
+	globalConfiguration.BackendsThrottleDuration = time.Duration(2 * time.Second)
 
 	return globalConfiguration
 }
diff --git a/docs/index.md b/docs/index.md
index 28f557a69..5644af607 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -107,6 +107,16 @@ For example:
 #
 # CertFile = "traefik.crt"
 # KeyFile = "traefik.key"
+
+# Backends throttle duration: minimum duration between 2 events from providers
+# before applying a new configuration. It avoids unnecessary reloads if multiples events
+# are sent in a short amount of time.
+#
+# Optional
+# Default: "2s"
+#
+# BackendsThrottleDuration = "5s"
+
 ```
 
 
diff --git a/traefik.go b/traefik.go
index 8b63f3dbf..4a3464f30 100644
--- a/traefik.go
+++ b/traefik.go
@@ -59,6 +59,8 @@ func main() {
 	var configurationRouter *mux.Router
 	var configurationChan = make(chan configMessage, 10)
 	defer close(configurationChan)
+	var configurationChanValidated = make(chan configMessage, 10)
+	defer close(configurationChanValidated)
 	var sigs = make(chan os.Signal, 1)
 	defer close(sigs)
 	var stopChan = make(chan bool)
@@ -96,10 +98,33 @@ func main() {
 
 	// listen new configurations from providers
 	go func() {
-
+		lastReceivedConfiguration := time.Unix(0, 0)
+		lastConfigs := make(map[string]*configMessage)
 		for {
 			configMsg := <-configurationChan
 			log.Infof("Configuration receveived from provider %s: %#v", configMsg.providerName, configMsg.configuration)
+			lastConfigs[configMsg.providerName] = &configMsg
+			if time.Now().After(lastReceivedConfiguration.Add(time.Duration(globalConfiguration.BackendsThrottleDuration))) {
+				log.Infof("Last %s config received more than %s, OK", configMsg.providerName, globalConfiguration.BackendsThrottleDuration)
+				// last config received more than n s ago
+				configurationChanValidated <- configMsg
+			} else {
+				log.Infof("Last %s config received less than %s, waiting...", configMsg.providerName, globalConfiguration.BackendsThrottleDuration)
+				go func() {
+					<-time.After(globalConfiguration.BackendsThrottleDuration)
+					if time.Now().After(lastReceivedConfiguration.Add(time.Duration(globalConfiguration.BackendsThrottleDuration))) {
+						log.Infof("Waited for %s config, OK", configMsg.providerName)
+						configurationChanValidated <- *lastConfigs[configMsg.providerName]
+					}
+				}()
+			}
+			lastReceivedConfiguration = time.Now()
+		}
+	}()
+	go func() {
+		for {
+			configMsg := <-configurationChanValidated
+			log.Debugf("Configuration %s", spew.Sdump(configMsg.configuration))
 			if configMsg.configuration == nil {
 				log.Info("Skipping empty configuration")
 			} else if reflect.DeepEqual(currentConfigurations[configMsg.providerName], configMsg.configuration) {
@@ -120,7 +145,7 @@ func main() {
 					newsrv := prepareServer(configurationRouter, globalConfiguration, oldServer, loggerMiddleware, metrics)
 					go startServer(newsrv, globalConfiguration)
 					srv = newsrv
-					time.Sleep(2 * time.Second)
+					time.Sleep(1 * time.Second)
 					if oldServer != nil {
 						log.Info("Stopping old server")
 						oldServer.Close()
diff --git a/traefik.sample.toml b/traefik.sample.toml
index 51d452609..9d824343c 100644
--- a/traefik.sample.toml
+++ b/traefik.sample.toml
@@ -44,6 +44,16 @@
 # CertFile = "traefik.crt"
 # KeyFile = "traefik.key"
 
+# Backends throttle duration: minimum duration between 2 events from providers
+# before applying a new configuration. It avoids unnecessary reloads if multiples events
+# are sent in a short amount of time.
+#
+# Optional
+# Default: "2s"
+#
+# BackendsThrottleDuration = "5s"
+
+
 ################################################################
 # Web configuration backend
 ################################################################