Support disabling database auto migration (#22053)

Gitea will migrate the database model version automatically, but it
should be able to be disabled and keep Gitea shutdown if the version is
not matched.

custom/conf/app.example.ini

 ;;
 ;; Database maximum number of open connections, default is 0 meaning no maximum
 ;MAX_OPEN_CONNS = 0
+;;
+;; Whether execute database models migrations automatically
+;AUTO_MIGRATION = true
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

docs/content/doc/advanced/config-cheat-sheet.en-us.md

 - `MAX_OPEN_CONNS` **0**: Database maximum open connections - default is 0, meaning there is no limit.
 - `MAX_IDLE_CONNS` **2**: Max idle database connections on connection pool, default is 2 - this will be capped to `MAX_OPEN_CONNS`.
 - `CONN_MAX_LIFETIME` **0 or 3s**: Sets the maximum amount of time a DB connection may be reused - default is 0, meaning there is no limit (except on MySQL where it is 3s - see #6804 & #7071).
+- `AUTO_MIGRATION` **true**: Whether execute database models migrations automatically.
 
 Please see #8540 & #8273 for further discussion of the appropriate values for `MAX_OPEN_CONNS`, `MAX_IDLE_CONNS` & `CONN_MAX_LIFETIME` and their
 relation to port exhaustion.

modules/doctor/dbversion.go

 )
 
 func checkDBVersion(ctx context.Context, logger log.Logger, autofix bool) error {
+	logger.Info("Expected database version: %d", migrations.ExpectedVersion())
 	if err := db.InitEngineWithMigration(ctx, migrations.EnsureUpToDate); err != nil {
 		if !autofix {
 			logger.Critical("Error: %v during ensure up to date", err)

modules/setting/database.go

 		MaxOpenConns      int
 		ConnMaxLifetime   time.Duration
 		IterateBufferSize int
+		AutoMigration     bool
 	}{
 		Timeout:           500,
 		IterateBufferSize: 50,
 	Database.LogSQL = sec.Key("LOG_SQL").MustBool(true)
 	Database.DBConnectRetries = sec.Key("DB_RETRIES").MustInt(10)
 	Database.DBConnectBackoff = sec.Key("DB_RETRY_BACKOFF").MustDuration(3 * time.Second)
+	Database.AutoMigration = sec.Key("AUTO_MIGRATION").MustBool(true)
 }
 
 // DBConnStr returns database connection string

routers/common/db.go

 	"code.gitea.io/gitea/models/migrations"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
+
+	"xorm.io/xorm"
 )
 
 // InitDBEngine In case of problems connecting to DB, retry connection. Eg, PGSQL in Docker Container on Synology
 		default:
 		}
 		log.Info("ORM engine initialization attempt #%d/%d...", i+1, setting.Database.DBConnectRetries)
-		if err = db.InitEngineWithMigration(ctx, migrations.Migrate); err == nil {
+		if err = db.InitEngineWithMigration(ctx, migrateWithSetting); err == nil {
 			break
 		} else if i == setting.Database.DBConnectRetries-1 {
 			return err
 	db.HasEngine = true
 	return nil
 }
+
+func migrateWithSetting(x *xorm.Engine) error {
+	if setting.Database.AutoMigration {
+		return migrations.Migrate(x)
+	}
+
+	if current, err := migrations.GetCurrentDBVersion(x); err != nil {
+		return err
+	} else if current < 0 {
+		// execute migrations when the database isn't initialized even if AutoMigration is false
+		return migrations.Migrate(x)
+	} else if expected := migrations.ExpectedVersion(); current != expected {
+		log.Fatal(`"database.AUTO_MIGRATION" is disabled, but current database version %d is not equal to the expected version %d.`+
+			`You can set "database.AUTO_MIGRATION" to true or migrate manually by running "gitea [--config /path/to/app.ini] migrate"`, current, expected)
+	}
+	return nil
+}