PMM-7220 Don't delete template if it is being used by rules (#599)

* PMM-7220 Don't delete template if it is being used by rules

* PMM-7220 add FindRuleByTemplateName helper

* PMM-7220 remove helper

* PMM-7220 don't ignore error

Co-authored-by: Alexey Palazhchenko <alexey.palazhchenko@percona.com>

models/template_helpers.go

@@ -183,13 +183,34 @@ func RemoveTemplate(q *reform.Querier, name string) error {
 		return err
 	}
 
-	err := q.Delete(&Template{Name: name})
+	inUse, err := templateInUse(q, name)
+	if err != nil {
+		return err
+	}
+
+	if inUse {
+		return errors.Errorf("failed to delete rule template, as it is being used by a rule")
+	}
+
+	err = q.Delete(&Template{Name: name})
 	if err != nil {
 		return errors.Wrap(err, "failed to delete rule template")
 	}
 	return nil
 }
 
+func templateInUse(q *reform.Querier, name string) (bool, error) {
+	_, err := q.FindOneFrom(RuleTable, "template_name", name)
+	switch err {
+	case nil:
+		return true, nil
+	case reform.ErrNoRows:
+		return false, nil
+	default:
+		return false, errors.WithStack(err)
+	}
+}
+
 func convertTemplateParams(params []alert.Parameter) (TemplateParams, error) {
 	res := make(TemplateParams, len(params))
 	for i, param := range params {

models/template_helpers_test.go

@@ -18,6 +18,7 @@ package models_test
 
 import (
 	"testing"
+	"time"
 
 	"github.com/brianvoe/gofakeit"
 	"github.com/percona-platform/saas/pkg/alert"
@@ -156,6 +157,31 @@ func TestRuleTemplates(t *testing.T) {
 		assert.Empty(t, templates)
 	})
 
+	t.Run("remove template in use", func(t *testing.T) {
+		tx, err := db.Begin()
+		require.NoError(t, err)
+		defer func() {
+			require.NoError(t, tx.Rollback())
+		}()
+
+		q := tx.Querier
+
+		name := gofakeit.UUID()
+
+		_, err = models.CreateTemplate(q, createTemplateParams(name))
+		require.NoError(t, err)
+
+		_ = createRule(t, q, name)
+
+		err = models.RemoveTemplate(q, name)
+		require.EqualError(t, err, "failed to delete rule template, as it is being used by a rule")
+
+		templates, err := models.FindTemplates(q)
+		require.NoError(t, err)
+
+		assert.NotEmpty(t, templates)
+	})
+
 	t.Run("list", func(t *testing.T) {
 		tx, err := db.Begin()
 		require.NoError(t, err)
@@ -236,3 +262,32 @@ func changeTemplateParams(name string) *models.ChangeTemplateParams {
 		},
 	}
 }
+
+func createRule(t *testing.T, q *reform.Querier, name string) string {
+	ch, err := models.CreateChannel(q, &models.CreateChannelParams{
+		Summary: "some summary",
+		EmailConfig: &models.EmailConfig{
+			To: []string{"test@test.test"},
+		},
+		Disabled: false,
+	})
+	require.NoError(t, err)
+	rule, err := models.CreateRule(q, &models.CreateRuleParams{
+		TemplateName: name,
+		Disabled:     true,
+		RuleParams: []models.RuleParam{
+			{
+				Name:       "test",
+				Type:       models.Float,
+				FloatValue: 3.14,
+			},
+		},
+		For:          5 * time.Second,
+		Severity:     common.Warning,
+		CustomLabels: map[string]string{"foo": "bar"},
+		Filters:      []models.Filter{{Type: models.Equal, Key: "value", Val: "10"}},
+		ChannelIDs:   []string{ch.ID},
+	})
+	require.NoError(t, err)
+	return rule.ID
+}