fix: check if tailnet with name already exists

internal/domain/repository.go

@@ -27,6 +27,7 @@ type Repository interface {
 
 	SaveTailnet(ctx context.Context, tailnet *Tailnet) error
 	GetTailnet(ctx context.Context, id uint64) (*Tailnet, error)
+	GetTailnetByName(ctx context.Context, name string) (*Tailnet, error)
 	ListTailnets(ctx context.Context) ([]Tailnet, error)
 	DeleteTailnet(ctx context.Context, id uint64) error
 

internal/domain/tailnet.go

@@ -72,6 +72,21 @@ func (r *repository) GetTailnet(ctx context.Context, id uint64) (*Tailnet, error
 	return &t, nil
 }
 
+func (r *repository) GetTailnetByName(ctx context.Context, name string) (*Tailnet, error) {
+	var t Tailnet
+	tx := r.withContext(ctx).Take(&t, "name = ?", name)
+
+	if errors.Is(tx.Error, gorm.ErrRecordNotFound) {
+		return nil, nil
+	}
+
+	if tx.Error != nil {
+		return nil, tx.Error
+	}
+
+	return &t, nil
+}
+
 func (r *repository) ListTailnets(ctx context.Context) ([]Tailnet, error) {
 	var tailnets = []Tailnet{}
 	tx := r.withContext(ctx).Find(&tailnets)

internal/service/tailnet.go

@@ -43,6 +43,14 @@ func (s *Service) CreateTailnet(ctx context.Context, req *connect.Request[api.Cr
 		return nil, connect.NewError(connect.CodePermissionDenied, fmt.Errorf("permission denied"))
 	}
 
+	check, err := s.repository.GetTailnetByName(ctx, req.Msg.Name)
+	if err != nil {
+		return nil, logError(err)
+	}
+	if check != nil {
+		return nil, connect.NewError(connect.CodeInvalidArgument, fmt.Errorf("tailnet with name '%s' already exists", req.Msg.Name))
+	}
+
 	if req.Msg.IamPolicy == nil {
 		req.Msg.IamPolicy = defaults.DefaultIAMPolicy()
 	}