[#100] server auto re-binding

Signed-off-by: Pavel Pogodaev <p.pogodaev@yadro.com>

cmd/http-gw/settings.go

@@ -51,11 +51,15 @@ const (
 
 	defaultNamespaceHeader = "X-Frostfs-Namespace"
 
+	defaultReconnectInterval = time.Minute
+
 	cfgServer      = "server"
 	cfgTLSEnabled  = "tls.enabled"
 	cfgTLSCertFile = "tls.cert_file"
 	cfgTLSKeyFile  = "tls.key_file"
 
+	cfgReconnectInterval = "reconnect_interval"
+
 	// Web.
 	cfgWebReadBufferSize     = "web.read_buffer_size"
 	cfgWebWriteBufferSize    = "web.write_buffer_size"
@@ -454,8 +458,18 @@ func getLogLevel(v *viper.Viper) (zapcore.Level, error) {
 	return lvl, nil
 }
 
-func fetchServers(v *viper.Viper) []ServerInfo {
+func fetchReconnectInterval(cfg *viper.Viper) time.Duration {
+	reconnect := cfg.GetDuration(cfgReconnectInterval)
+	if reconnect <= 0 {
+		reconnect = defaultReconnectInterval
+	}
+
+	return reconnect
+}
+
+func fetchServers(v *viper.Viper, log *zap.Logger) []ServerInfo {
 	var servers []ServerInfo
+	seen := make(map[string]struct{})
 
 	for i := 0; ; i++ {
 		key := cfgServer + "." + strconv.Itoa(i) + "."
@@ -470,6 +484,11 @@ func fetchServers(v *viper.Viper) []ServerInfo {
 			break
 		}
 
+		if _, ok := seen[serverInfo.Address]; ok {
+			log.Warn(logs.WarnDuplicateAddress, zap.String("address", serverInfo.Address))
+			continue
+		}
+		seen[serverInfo.Address] = struct{}{}
 		servers = append(servers, serverInfo)
 	}