fix(CSI-260): lookup of NFS interface group fails when empty name pro…

…vided

pkg/wekafs/apiclient/interfacegroup.go

@@ -152,42 +152,45 @@ func (a *ApiClient) fetchNfsInterfaceGroup(ctx context.Context, name *string, us
 	if len(*igs) == 0 {
 		return errors.New("no nfs interface groups found")
 	}
-	if name != nil {
-		for _, ig := range *igs {
-			if ig.Name == *name {
-				a.NfsInterfaceGroups[*name] = &ig
+
+	// according to calling function, if name is not provided, useDefault is set to true
+	if useDefault {
+		// If no name is provided, use the first IG that has at least one IP. useDefault is true -> name not provided!
+		for _, ig := range a.NfsInterfaceGroups {
+			if len(ig.Ips) > 0 {
+				a.NfsInterfaceGroups["default"] = ig
+				sort.Strings(a.NfsInterfaceGroups["default"].Ips)
+				return nil
 			}
 		}
-	} else if useDefault {
-		a.NfsInterfaceGroups["default"] = &(*igs)[0]
-	}
-
-	ig := &InterfaceGroup{}
-	if name != nil {
-		ig = a.NfsInterfaceGroups[*name]
-	} else {
-		ig = a.NfsInterfaceGroups["default"]
-	}
-	if ig == nil {
-		return errors.New("no nfs interface group found")
+		return errors.New("no nfs interface group with IP addresses found")
 	}
 
-	if len(ig.Ips) == 0 {
-		return errors.New("no IP addresses found for nfs interface group")
+	for _, ig := range *igs {
+		if ig.Name == *name {
+			if len(ig.Ips) == 0 {
+				return errors.New("no IP addresses found for nfs interface group \"" + *name + "\"")
+			}
+			a.NfsInterfaceGroups[ig.Name] = &ig
+			sort.Strings(a.NfsInterfaceGroups[ig.Name].Ips)
+			return nil
+		}
+		return errors.New(fmt.Sprintf("no nfs interface group named '%s' found", *name))
 	}
-	// Make sure the IPs are always sorted
-	sort.Strings(ig.Ips)
-	return nil
+	return errors.New("no valid nfs interface group found")
 }
 
 func (a *ApiClient) GetNfsInterfaceGroup(ctx context.Context, name *string) *InterfaceGroup {
 	igName := "default"
-	if name != nil {
+	useDefault := false
+	if name != nil && *name != "" {
 		igName = *name
+	} else {
+		useDefault = true
 	}
 	_, ok := a.NfsInterfaceGroups[igName]
 	if !ok {
-		err := a.fetchNfsInterfaceGroup(ctx, name, true)
+		err := a.fetchNfsInterfaceGroup(ctx, name, useDefault)
 		if err != nil {
 			return nil
 		}