Alerting: modify DB table, accessors and migration to restrict org access (#37414)

* Alerting: modify table and accessors to limit org access appropriately

* Update migration to create multiple Alertmanager configs

* Apply suggestions from code review

Co-authored-by: gotjosh <josue@grafana.com>

* replace mg.ClearMigrationEntry()

mg.ClearMigrationEntry() would create a new session.
This commit introduces a new migration for clearing an entry from migration log for replacing  mg.ClearMigrationEntry() so that all dashboard alert migration operations will run inside the same transaction.
It adds also `SkipMigrationLog()` in Migrator interface for skipping adding an entry in the migration_log.

Co-authored-by: gotjosh <josue@grafana.com>

pkg/services/sqlstore/migrator/migrations.go

@@ -21,6 +21,10 @@ func (m *MigrationBase) GetCondition() MigrationCondition {
 	return m.Condition
 }
 
+func (m *MigrationBase) SkipMigrationLog() bool {
+	return false
+}
+
 type RawSQLMigration struct {
 	MigrationBase
 

pkg/services/sqlstore/migrator/migrator.go

@@ -108,13 +108,17 @@ func (mg *Migrator) Start() error {
 			if err != nil {
 				mg.Logger.Error("Exec failed", "error", err, "sql", sql)
 				record.Error = err.Error()
-				if _, err := sess.Insert(&record); err != nil {
-					return err
+				if !m.SkipMigrationLog() {
+					if _, err := sess.Insert(&record); err != nil {
+						return err
+					}
 				}
 				return err
 			}
 			record.Success = true
-			_, err = sess.Insert(&record)
+			if !m.SkipMigrationLog() {
+				_, err = sess.Insert(&record)
+			}
 			if err == nil {
 				migrationsPerformed++
 			}
@@ -171,16 +175,6 @@ func (mg *Migrator) exec(m Migration, sess *xorm.Session) error {
 	return nil
 }
 
-func (mg *Migrator) ClearMigrationEntry(id string) error {
-	sess := mg.x.NewSession()
-	defer sess.Close()
-	_, err := sess.SQL(`DELETE from migration_log where migration_id = ?`, id).Query()
-	if err != nil {
-		return fmt.Errorf("failed to clear migration entry %v: %w", id, err)
-	}
-	return nil
-}
-
 type dbTransactionFunc func(sess *xorm.Session) error
 
 func (mg *Migrator) InTransaction(callback dbTransactionFunc) error {

pkg/services/sqlstore/migrator/types.go

@@ -19,6 +19,10 @@ type Migration interface {
 	Id() string
 	SetId(string)
 	GetCondition() MigrationCondition
+	// SkipMigrationLog is used by dashboard alert migration to Grafana 8 Alerts
+	// for skipping recording it in the migration_log so that it can run several times.
+	// For all the other migrations it should be false.
+	SkipMigrationLog() bool
 }
 
 type CodeMigration interface {