[client] Fix duplicate log lines in containers (#5609)

client/cmd/service_controller.go

@@ -103,7 +103,7 @@ func (p *program) Stop(srv service.Service) error {
 
 // Common setup for service control commands
 func setupServiceControlCommand(cmd *cobra.Command, ctx context.Context, cancel context.CancelFunc) (service.Service, error) {
-	SetFlagsFromEnvVars(rootCmd)
+	// rootCmd env vars are already applied by PersistentPreRunE.
 	SetFlagsFromEnvVars(serviceCmd)
 
 	cmd.SetOut(cmd.OutOrStdout())

util/log.go

@@ -43,7 +43,13 @@ func InitLogger(logger *log.Logger, logLevel string, logs ...string) error {
 	var writers []io.Writer
 	logFmt := os.Getenv("NB_LOG_FORMAT")
 
+	seen := make(map[string]bool, len(logs))
 	for _, logPath := range logs {
+		if seen[logPath] {
+			continue
+		}
+		seen[logPath] = true
+
 		switch logPath {
 		case LogSyslog:
 			AddSyslogHookToLogger(logger)