feat(db): back up database before running migrations

Just in case.

invokeai/app/services/shared/sqlite_migrator/sqlite_migrator_impl.py

@@ -1,4 +1,6 @@
 import sqlite3
+from contextlib import closing
+from datetime import datetime
 from pathlib import Path
 from typing import Optional
 
@@ -32,6 +34,7 @@ class SqliteMigrator:
         self._db = db
         self._logger = db.logger
         self._migration_set = MigrationSet()
+        self._backup_path: Optional[Path] = None
 
     def register_migration(self, migration: Migration) -> None:
         """Registers a migration."""
@@ -55,6 +58,18 @@ class SqliteMigrator:
                 return False
 
             self._logger.info("Database update needed")
+
+            # Make a backup of the db if it needs to be updated and is a file db
+            if self._db.db_path is not None:
+                timestamp = datetime.now().strftime("%Y%m%d-%H%M%S")
+                self._backup_path = self._db.db_path.parent / f"{self._db.db_path.stem}_backup_{timestamp}.db"
+                self._logger.info(f"Backing up database to {str(self._backup_path)}")
+                # Use SQLite to do the backup
+                with closing(sqlite3.connect(self._backup_path)) as backup_conn:
+                    self._db.conn.backup(backup_conn)
+            else:
+                self._logger.info("Using in-memory database, no backup needed")
+
             next_migration = self._migration_set.get(from_version=self._get_current_version(cursor))
             while next_migration is not None:
                 self._run_migration(next_migration)

tests/test_sqlite_migrator.py

@@ -250,6 +250,32 @@ def test_migrator_runs_all_migrations_file(logger: Logger) -> None:
         db.conn.close()
 
 
+def test_migrator_backs_up_db(logger: Logger) -> None:
+    with TemporaryDirectory() as tempdir:
+        original_db_path = Path(tempdir) / "invokeai.db"
+        db = SqliteDatabase(db_path=original_db_path, logger=logger, verbose=False)
+        # Write some data to the db to test for successful backup
+        temp_cursor = db.conn.cursor()
+        temp_cursor.execute("CREATE TABLE test (id INTEGER PRIMARY KEY);")
+        db.conn.commit()
+        # Set up the migrator
+        migrator = SqliteMigrator(db=db)
+        migrations = [Migration(from_version=i, to_version=i + 1, callback=create_migrate(i)) for i in range(0, 3)]
+        for migration in migrations:
+            migrator.register_migration(migration)
+        migrator.run_migrations()
+        # Must manually close else we get an error on Windows
+        db.conn.close()
+        assert original_db_path.exists()
+        # We should have a backup file when we migrated a file db
+        assert migrator._backup_path
+        # Check that the test table exists as a proxy for successful backup
+        with closing(sqlite3.connect(migrator._backup_path)) as backup_db_conn:
+            backup_db_cursor = backup_db_conn.cursor()
+            backup_db_cursor.execute("SELECT name FROM sqlite_master WHERE type='table' AND name='test';")
+            assert backup_db_cursor.fetchone() is not None
+
+
 def test_migrator_makes_no_changes_on_failed_migration(
     migrator: SqliteMigrator, migration_no_op: Migration, failing_migrate_callback: MigrateCallback
 ) -> None: