Alerting: Keep track of individual org migration status (#78369)

* Alerting: Keep track of individual org migration status

Save migration status per migrated org.

Change the meaning (and key/value) of the org_id=0 entry 
to store the current (previous) config value used by alerting. 
This is so we can know when to upgrade/downgrade by 
comparing with the new config value in 
UnifiedAlerting.IsEnabled.

pkg/services/sqlstore/migrations/migrations.go

@@ -111,6 +111,8 @@ func (*OSSMigrations) AddMigration(mg *Migrator) {
 	dashboardFolderMigrations.AddDashboardFolderMigrations(mg)
 
 	ssosettings.AddMigration(mg)
+
+	ualert.CreateOrgMigratedKVStoreEntries(mg)
 }
 
 func addStarMigrations(mg *Migrator) {

pkg/services/sqlstore/migrations/ualert/org_upgrade_state_mig.go

@@ -0,0 +1,102 @@
+package ualert
+
+import (
+	"fmt"
+
+	"xorm.io/xorm"
+
+	"github.com/grafana/grafana/pkg/services/sqlstore/migrator"
+)
+
+// typeKey is a vendored migration.typeKey.
+var typeKey = "currentAlertingType"
+
+// AlertingType is a vendored migration.store.AlertingType.
+type alertingType string
+
+const (
+	Legacy          alertingType = "Legacy"
+	UnifiedAlerting alertingType = "UnifiedAlerting"
+)
+
+// CreateOrgMigratedKVStoreEntries creates kv store entries for each organization if the migration has been run.
+// This is needed now that we've changed the semantics of data loss when upgrading / rolling back. If a user who previously
+// upgraded were to rollback and upgrade again without clean_upgrade, then since they don't have org-level migrated states
+// it will attempt to upgrade their orgs as if they had never upgraded before. This will almost definitely fail with
+// duplicate key errors.
+//
+// In addition, this changes the entry for orgId=0 to be better named as it no longer tracks whether the
+// migration has been run, but rather the current alerting type of Grafana; Legacy or UnifiedAlerting. This is used to
+// detect transitions between Legacy and UnifiedAlerting by comparing to the desired type in the configuration.
+func CreateOrgMigratedKVStoreEntries(mg *migrator.Migrator) {
+	mg.AddMigration("copy kvstore migration status to each org", &createOrgMigratedKVStoreEntries{})
+}
+
+type createOrgMigratedKVStoreEntries struct {
+	migrator.MigrationBase
+}
+
+func (c createOrgMigratedKVStoreEntries) SQL(migrator.Dialect) string {
+	return codeMigration
+}
+
+func (c createOrgMigratedKVStoreEntries) Exec(sess *xorm.Session, mg *migrator.Migrator) error {
+	var anyOrg int64 = 0
+	migrated := kvStoreV1Entry{
+		OrgID:     &anyOrg,
+		Namespace: &KVNamespace,
+		Key:       &migratedKey,
+	}
+	has, err := sess.Table("kv_store").Get(&migrated)
+	if err != nil {
+		return err
+	}
+
+	if !has {
+		mg.Logger.Debug("No migrated status in kvstore, nothing to set")
+		return nil
+	}
+
+	// Rename old entry key and value.
+	val := Legacy
+	if migrated.Value == "true" {
+		val = UnifiedAlerting
+	}
+	if _, err := sess.Table("kv_store").Where("id = ?", migrated.ID).Update(&kvStoreV1Entry{
+		Key:   &typeKey,
+		Value: string(val),
+	}); err != nil {
+		mg.Logger.Error("failed to rename org migrated status in kvstore", "err", err)
+		return err
+	}
+
+	var orgs []struct {
+		ID int64 `xorm:"id"`
+	}
+	if err := sess.SQL("select id from org").Find(&orgs); err != nil {
+		return err
+	}
+
+	if len(orgs) == 0 {
+		mg.Logger.Debug("no orgs, nothing to set in kvstore")
+		return nil
+	}
+
+	for _, org := range orgs {
+		id := org.ID
+		entry := kvStoreV1Entry{
+			OrgID:     &id,
+			Namespace: &KVNamespace,
+			Key:       &migratedKey,
+			Value:     migrated.Value,
+			Created:   migrated.Created,
+			Updated:   migrated.Updated,
+		}
+		if _, errCreate := sess.Table("kv_store").Insert(&entry); errCreate != nil {
+			mg.Logger.Error("failed to insert org migration status to kvstore", "err", errCreate)
+			return fmt.Errorf("failed to insert org migration status to kvstore: %w", errCreate)
+		}
+	}
+
+	return nil
+}