import logging import sys from logging.config import fileConfig from alembic import context from sqlalchemy import engine_from_config, pool # this is the Alembic Config object, which provides # access to the values within the .ini file in use. config = context.config # Interpret the config file for Python logging. # This line sets up loggers basically. if 'jupyterhub' in sys.modules: from traitlets.config import MultipleInstanceError from jupyterhub.app import JupyterHub app = None if JupyterHub.initialized(): try: app = JupyterHub.instance() except MultipleInstanceError: # could have been another Application pass if app is not None: alembic_logger = logging.getLogger('alembic') alembic_logger.propagate = True alembic_logger.parent = app.log else: fileConfig(config.config_file_name, disable_existing_loggers=False) else: fileConfig(config.config_file_name) # add your model's MetaData object here for 'autogenerate' support from jupyterhub import orm target_metadata = orm.Base.metadata # other values from the config, defined by the needs of env.py, # can be acquired: # my_important_option = config.get_main_option("my_important_option") # ... etc. # pass these to context.configure(**config_opts) common_config_opts = dict( # target_metadata for autogenerate target_metadata=target_metadata, # transaction per migration to ensure # each migration is 'complete' before running the next one # (e.g. dropped tables) transaction_per_migration=True, ) def run_migrations_offline(): """Run migrations in 'offline' mode. This configures the context with just a URL and not an Engine, though an Engine is acceptable here as well. By skipping the Engine creation we don't even need a DBAPI to be available. Calls to context.execute() here emit the given string to the script output. """ connectable = config.attributes.get('connection', None) config_opts = {} config_opts.update(common_config_opts) config_opts["literal_binds"] = True if connectable is None: config_opts["url"] = config.get_main_option("sqlalchemy.url") else: config_opts["connection"] = connectable context.configure(**config_opts) with context.begin_transaction(): context.run_migrations() def run_migrations_online(): """Run migrations in 'online' mode. In this scenario we need to create an Engine and associate a connection with the context. """ connectable = config.attributes.get('connection', None) config_opts = {} config_opts.update(common_config_opts) if connectable is None: connectable = engine_from_config( config.get_section(config.config_ini_section), prefix='sqlalchemy.', poolclass=pool.NullPool, ) with connectable.connect() as connection: context.configure( connection=connection, **common_config_opts, ) with context.begin_transaction(): context.run_migrations() if context.is_offline_mode(): run_migrations_offline() else: run_migrations_online()