Add rollback command

cmd/gotosocial/action/debug/rollback/rollback.go

@@ -0,0 +1,12 @@
+package rollback
+
+import (
+	"context"
+
+	"github.com/superseriousbusiness/gotosocial/cmd/gotosocial/action"
+	"github.com/superseriousbusiness/gotosocial/internal/db/bundb"
+)
+
+var Rollback action.GTSAction = func(ctx context.Context) (err error) {
+	return bundb.DoRollback(ctx)
+}

cmd/gotosocial/debug.go

@@ -20,6 +20,7 @@ package main
 import (
 	"github.com/spf13/cobra"
 	configaction "github.com/superseriousbusiness/gotosocial/cmd/gotosocial/action/debug/config"
+	rollbackaction "github.com/superseriousbusiness/gotosocial/cmd/gotosocial/action/debug/rollback"
 	"github.com/superseriousbusiness/gotosocial/internal/config"
 )
 
@@ -41,5 +42,17 @@ func debugCommands() *cobra.Command {
 	}
 	config.AddServerFlags(debugConfigCmd)
 	debugCmd.AddCommand(debugConfigCmd)
+
+	debugRollbackCmd := &cobra.Command{
+		Use:   "rollback",
+		Short: "roll back the last run database migration",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return run(cmd.Context(), rollbackaction.Rollback)
+		},
+	}
+
+	config.AddServerFlags(debugRollbackCmd)
+	debugCmd.AddCommand(debugRollbackCmd)
+
 	return debugCmd
 }

internal/db/bundb/bundb.go

@@ -130,6 +130,49 @@ func doMigration(ctx context.Context, db *bun.DB) error {
 	return nil
 }
 
+func DoRollback(ctx context.Context) error {
+	var sqldb *sql.DB
+	var dialect func() schema.Dialect
+	var err error
+
+	switch t := strings.ToLower(config.GetDbType()); t {
+	case "postgres":
+		sqldb, dialect, err = pgConn(ctx)
+		if err != nil {
+			return err
+		}
+	case "sqlite":
+		sqldb, dialect, err = sqliteConn(ctx)
+		if err != nil {
+			return err
+		}
+	default:
+		return fmt.Errorf("database type %s not supported for bundb", t)
+	}
+
+	db := bunDB(sqldb, dialect)
+
+	migrator := migrate.NewMigrator(db, migrations.Migrations)
+
+	if err := migrator.Lock(ctx); err != nil {
+		return err
+	}
+	defer migrator.Unlock(ctx) //nolint:errcheck
+
+	group, err := migrator.Rollback(ctx)
+	if err != nil {
+		return err
+	}
+
+	if group.IsZero() {
+		fmt.Printf("there are no groups to roll back\n")
+		return nil
+	}
+
+	fmt.Printf("rolled back %s\n", group)
+	return nil
+}
+
 // NewBunDBService returns a bunDB derived from the provided config, which implements the go-fed DB interface.
 // Under the hood, it uses https://github.com/uptrace/bun to create and maintain a database connection.
 func NewBunDBService(ctx context.Context, state *state.State) (db.DB, error) {