Don't exit tablet server on reloading invalid ACL

This fixes potentially bringing down a tablet with an innocuous SIGHUP.

It also logs the fact it's reading the ACL file, to fix not getting any
feedback on SIGHUP.

#17139

Signed-off-by: Wiebe Cazemier <wiebe@ytec.nl>

go/vt/tableacl/tableacl.go

@@ -107,14 +107,14 @@ func (tacl *tableACL) init(configFile string, aclCB func()) error {
 	}
 	data, err := os.ReadFile(configFile)
 	if err != nil {
-		log.Infof("unable to read tableACL config file: %v  Error: %v", configFile, err)
+		log.Errorf("unable to read tableACL config file: %v  Error: %v", configFile, err)
 		return err
 	}
 	config := &tableaclpb.Config{}
 	if err := config.UnmarshalVT(data); err != nil {
 		// try to parse tableacl as json file
 		if jsonErr := json2.UnmarshalPB(data, config); jsonErr != nil {
-			log.Infof("unable to parse tableACL config file as a protobuf or json file.  protobuf err: %v  json err: %v", err, jsonErr)
+			log.Errorf("unable to parse tableACL config file as a protobuf or json file.  protobuf err: %v  json err: %v", err, jsonErr)
 			return fmt.Errorf("unable to unmarshal Table ACL data: %s", data)
 		}
 	}

go/vt/vttablet/tabletserver/tabletserver.go

@@ -382,8 +382,9 @@ func (tsv *TabletServer) InitACL(tableACLConfigFile string, enforceTableACLConfi
 	sigChan := make(chan os.Signal, 1)
 	signal.Notify(sigChan, syscall.SIGHUP)
 	go func() {
-		for range sigChan {
-			tsv.initACL(tableACLConfigFile, enforceTableACLConfig)
+		for sig := range sigChan {
+			log.Infof("Signal '%v' received, reloading ACL", sig)
+			tsv.initACL(tableACLConfigFile, false)
 		}
 	}()