MEDIUM: Fixed reload handling

On reload (SIGUSR1) we now reload the runtime API client by
rereading the configuration, and we use a separate signal (SIGUSR2)
to reread the config file.

Use case is when you write the file manually you can reread the
config to memory using SIGUSR2 signal. This will stop additional
disk I/O every time haproxy master process sends SIGUSR1 signal
to the dataplane API when started from program section.

Author: mjuraga

configure_data_plane.go

@@ -129,20 +129,12 @@ func configureAPI(api *operations.DataPlaneAPI) http.Handler {
 
 	api.ServerShutdown = serverShutdown
 
-	c := configureNativeClient()
-	client := &c
+	client := configureNativeClient()
 
 	// Handle reload signals
 	sigs := make(chan os.Signal, 1)
-	signal.Notify(sigs, syscall.SIGUSR1)
-
-	go func() {
-		sig := <-sigs
-		if sig == syscall.SIGUSR1 {
-			c = configureNativeClient()
-			log.Info("Reloaded Data Plane API")
-		}
-	}()
+	signal.Notify(sigs, syscall.SIGUSR1, syscall.SIGUSR2)
+	go handleSignals(sigs, client)
 
 	// Initialize reload agent
 	ra := &haproxy.ReloadAgent{}
@@ -476,7 +468,7 @@ func serverShutdown() {
 	}
 }
 
-func configureNativeClient() client_native.HAProxyClient {
+func configureNativeClient() *client_native.HAProxyClient {
 	// Override options with env variables
 	if os.Getenv("HAPROXY_MWORKER") == "1" {
 		masterRuntime := os.Getenv("HAPROXY_MASTER_CLI")
@@ -490,16 +482,9 @@ func configureNativeClient() client_native.HAProxyClient {
 		haproxyOptions.ConfigFile = cfg[0]
 	}
 	// Initialize HAProxy native client
-	confClient := &configuration.Client{}
-	confParams := configuration.ClientParams{
-		ConfigurationFile: haproxyOptions.ConfigFile,
-		Haproxy:           haproxyOptions.HAProxy,
-		UseValidation:     false,
-		TransactionDir:    haproxyOptions.TransactionDir,
-	}
-	err := confClient.Init(confParams)
+	confClient, err := configureConfigurationClient()
 	if err != nil {
-		log.Fatalf("Error setting up configuration client: %s", err.Error())
+		log.Fatalf(err.Error())
 	}
 
 	runtimeClient := configureRuntimeClient(confClient)
@@ -508,7 +493,23 @@ func configureNativeClient() client_native.HAProxyClient {
 		log.Fatalf("Error setting up native client: %s", err.Error())
 	}
 
-	return *client
+	return client
+}
+
+func configureConfigurationClient() (*configuration.Client, error) {
+	confClient := &configuration.Client{}
+	confParams := configuration.ClientParams{
+		ConfigurationFile:      haproxyOptions.ConfigFile,
+		Haproxy:                haproxyOptions.HAProxy,
+		UseValidation:          false,
+		PersistentTransactions: false,
+		TransactionDir:         haproxyOptions.TransactionDir,
+	}
+	err := confClient.Init(confParams)
+	if err != nil {
+		return nil, fmt.Errorf("Error setting up configuration client: %s", err.Error())
+	}
+	return confClient, nil
 }
 
 func configureRuntimeClient(confClient *configuration.Client) *runtime_api.Client {
@@ -551,3 +552,22 @@ func configureRuntimeClient(confClient *configuration.Client) *runtime_api.Clien
 	}
 	return runtimeClient
 }
+
+func handleSignals(sigs chan os.Signal, client *client_native.HAProxyClient) {
+	for {
+		select {
+		case sig := <-sigs:
+			if sig == syscall.SIGUSR1 {
+				client.Runtime = configureRuntimeClient(client.Configuration)
+				log.Info("Reloaded Data Plane API")
+			} else if sig == syscall.SIGUSR2 {
+				confClient, err := configureConfigurationClient()
+				if err != nil {
+					log.Fatalf(err.Error())
+				}
+				log.Info("Rereading Configuration Files")
+				client.Configuration = confClient
+			}
+		}
+	}
+}