text: import logging
  from logging.config import fileConfig
  import re
  
  from sqlalchemy import create_engine
  from sqlalchemy import pool
  
  from alembic import context
  
  from renewer.extensions import config as renewer_config
  from renewer.models.cdn import CdnModel
  from renewer.models.domain import DomainModel
  
  USE_TWOPHASE = False
  
  # 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.
  fileConfig(config.config_file_name)
  logger = logging.getLogger("alembic.env")
  
  # gather section names referring to different
  # databases.  These are named "engine1", "engine2"
  # in the sample .ini file.
  db_names = config.get_main_option("databases")
  
  # add your model's MetaData objects here
  # for 'autogenerate' support.  These must be set
  # up to hold just those tables targeting a
  # particular database. table.tometadata() may be
  # helpful here in case a "copy" of
  # a MetaData is needed.
  # from myapp import mymodel
  # target_metadata = {
  #       'engine1':mymodel.metadata1,
  #       'engine2':mymodel.metadata2
  # }
  target_metadata = {"cdn": CdnModel.metadata, "domain": DomainModel.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.
  
  
  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.
  
      """
      # for the --sql use case, run migrations for each URL into
      # individual files.
  
      engines = {}
  
      engines["cdn"] = rec = {}
      rec["url"] = create_engine(renewer_config.CDN_BROKER_DATABASE_URI)
      engines["domain"] = rec = {}
      rec["url"] = create_engine(renewer_config.DOMAIN_BROKER_DATABASE_URI)
  
      for name, rec in engines.items():
          logger.info("Migrating database %s" % name)
          file_ = "%s.sql" % name
          logger.info("Writing output to %s" % file_)
          with open(file_, "w") as buffer:
              context.configure(
                  url=rec["url"],
                  output_buffer=buffer,
                  target_metadata=target_metadata.get(name),
                  literal_binds=True,
                  dialect_opts={"paramstyle": "named"},
              )
              with context.begin_transaction():
                  context.run_migrations(engine_name=name)
  
  
  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.
  
      """
  
      # for the direct-to-DB use case, start a transaction on all
      # engines, then run all migrations, then commit all transactions.
  
      engines = {}
  
      engines["cdn"] = rec = {}
      rec["engine"] = create_engine(renewer_config.CDN_BROKER_DATABASE_URI)
      engines["domain"] = rec = {}
      rec["engine"] = create_engine(renewer_config.DOMAIN_BROKER_DATABASE_URI)
  
      for name, rec in engines.items():
          engine = rec["engine"]
          rec["connection"] = conn = engine.connect()
  
          if USE_TWOPHASE:
              rec["transaction"] = conn.begin_twophase()
          else:
              rec["transaction"] = conn.begin()
  
      try:
          for name, rec in engines.items():
              logger.info("Migrating database %s" % name)
              context.configure(
                  connection=rec["connection"],
                  upgrade_token="%s_upgrades" % name,
                  downgrade_token="%s_downgrades" % name,
                  target_metadata=target_metadata.get(name),
              )
              context.run_migrations(engine_name=name)
  
          if USE_TWOPHASE:
              for rec in engines.values():
                  rec["transaction"].prepare()
  
          for rec in engines.values():
              rec["transaction"].commit()
      except:
          for rec in engines.values():
              rec["transaction"].rollback()
          raise
      finally:
          for rec in engines.values():
              rec["connection"].close()
  
  
  if context.is_offline_mode():
      run_migrations_offline()
  else:
      run_migrations_online()
  