# -*- coding: utf-8 -*-
"""Alembic environment configuration for database migrations.
Copyright 2025
SPDX-License-Identifier: Apache-2.0
Authors: Mihai Criveti, Madhav Kandukuri
This module configures the Alembic migration environment for the MCP Gateway
application. It sets up both offline and online migration modes, configures
logging, and establishes the database connection parameters.
The module performs the following key functions:
- Configures Alembic to locate migration scripts in the mcpgateway package
- Sets up Python logging based on the alembic.ini configuration
- Imports the SQLAlchemy metadata from the application models
- Configures the database URL from application settings
- Provides functions for running migrations in both offline and online modes
Offline mode generates SQL scripts without connecting to the database, while
online mode executes migrations directly against a live database connection.
Attributes:
config (Config): The Alembic configuration object loaded from alembic.ini.
target_metadata (MetaData): SQLAlchemy metadata object containing all
table definitions from the application models.
Examples:
Running migrations in offline mode::
alembic upgrade head --sql
Running migrations in online mode::
alembic upgrade head
The module is typically not imported directly but is used by Alembic
when executing migration commands.
Note:
This file is automatically executed by Alembic and should not be
imported or run directly by application code.
"""
# Standard
from importlib.resources import files
from logging.config import fileConfig
# Third-Party
from alembic import context
# this is the Alembic Config object, which provides
# access to the values within the .ini file in use.
from alembic.config import Config
from sqlalchemy import engine_from_config, pool
# First-Party
from mcpgateway.config import settings
from mcpgateway.db import Base
# from mcpgateway.db import get_metadata
# target_metadata = get_metadata()
# Create config object - this is the standard way in Alembic
config = Config()
config.set_main_option("script_location", str(files("mcpgateway").joinpath("alembic")))
# Interpret the config file for Python logging.
# This line sets up loggers basically.
if config.config_file_name is not None:
fileConfig(
config.config_file_name,
disable_existing_loggers=False,
)
# First-Party
# add your model's MetaData object here
# for 'autogenerate' support
# from myapp import mymodel
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.
config.set_main_option(
"sqlalchemy.url",
settings.database_url,
)
def run_migrations_offline() -> None:
"""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() -> None:
"""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()
# Only run migrations if executed as a script (not on import)
if __name__ == "__main__":
if context.is_offline_mode():
run_migrations_offline()
else:
run_migrations_online()
