Alembic not loading config member

Question

We're working on a project which uses Postgresql as a data source which is then managed/initiated using SqlAlchemy to create models, and Alembic for migrations.

The issue is that Alembic cannot auto-generate any new migrations, nor can it upgrade the database to the latest iteration when using the Alembic command. When done programmatically the database version upgrades fine, but we're unable to generate new revisions. There are multiple errors that can show up depending on minor changes in alembics env.py script but essentially hey come down to issues with contexts config member.

Here is the folder structure:

my-project
│   alembic.ini
│
└───alembic
│   │   env.py
│   │   README
│   │   script.py.mako
│   │
│   └───versions
│       │   95ba8c1c3126_some_revision.py
│       │   43700c722f83_other_revision.py
│       │   ...

here are the relevant information from alembic.ini (everything else is default)

[alembic]
script_location = alembic
.
.
.
prepend_sys_path = .
.
.
.

# set this in env.py so we don't need to commit the database password
sqlalchemy.url = NULL

and here is env.py:

from logging.config import fileConfig

from sqlalchemy import engine_from_config
from sqlalchemy import pool

from alembic import context


# 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, disable_existing_loggers=False)

# add your model's MetaData object here
# for 'autogenerate' support
# from myapp import mymodel
# target_metadata = mymodel.Base.metadata

from core.database.database import Base, get_database_url

config.set_main_option('sqlalchemy.url', get_database_url())
target_metadata = 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.


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.

    """
    url = config.get_main_option("sqlalchemy.url")
    context.configure(
        url=url,
        target_metadata=target_metadata,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
    )

    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 = engine_from_config(
        config.get_section(config.config_ini_section),
        prefix="sqlalchemy.",
        poolclass=pool.NullPool,
    )

    with connectable.connect() as connection:
        context.configure(
            connection=connection, target_metadata=target_metadata
        )

        with context.begin_transaction():
            context.run_migrations()


if context.is_offline_mode():
    run_migrations_offline()
else:
    run_migrations_online()

this is the error I receive when running something like alembic revision -m "Add maintenances" --autogenerate from the same directory where 'alembic.ini' is located error:

INFO  [alembic.runtime.migration] Context impl PostgresqlImpl.
INFO  [alembic.runtime.migration] Will assume transactional DDL.
Traceback (most recent call last):
  File "/home/marco_rocco/.local/lib/python3.9/site-packages/alembic/command.py", line 212, in revision
    script_directory.run_env()
  File "/home/marco_rocco/.local/lib/python3.9/site-packages/alembic/script/base.py", line 490, in run_env
    util.load_python_file(self.dir, "env.py")
  File "/home/marco_rocco/.local/lib/python3.9/site-packages/alembic/util/pyfiles.py", line 97, in load_python_file
    module = load_module_py(module_id, path)
  File "/home/marco_rocco/.local/lib/python3.9/site-packages/alembic/util/compat.py", line 184, in load_module_py
    spec.loader.exec_module(module)
  File "<frozen importlib._bootstrap_external>", line 790, in exec_module
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "alembic/env.py", line 83, in <module>
    if context.is_offline_mode():
  File "<string>", line 8, in is_offline_mode
AttributeError: 'NoneType' object has no attribute 'is_offline_mode'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/marco_rocco/.local/bin/alembic", line 8, in <module>
    sys.exit(main())
  File "/home/marco_rocco/.local/lib/python3.9/site-packages/alembic/config.py", line 559, in main
    CommandLine(prog=prog).main(argv=argv)
  File "/home/marco_rocco/.local/lib/python3.9/site-packages/alembic/config.py", line 553, in main
    self.run_cmd(cfg, options)
  File "/home/marco_rocco/.local/lib/python3.9/site-packages/alembic/config.py", line 530, in run_cmd
    fn(
  File "/home/marco_rocco/.local/lib/python3.9/site-packages/alembic/command.py", line 212, in revision
    script_directory.run_env()
  File "/home/marco_rocco/.local/lib/python3.9/site-packages/alembic/runtime/environment.py", line 110, in __exit__
    self._remove_proxy()
  File "/home/marco_rocco/.local/lib/python3.9/site-packages/alembic/util/langhelpers.py", line 50, in _remove_proxy
    del globals_[attr_name]
KeyError: 'config'

Alembic not loading config member

0 Answers0