new comments

alembic/env.py

@@ -1,18 +1,22 @@
+"""Alembic environment configuration for database migrations.
+
+Configures offline and online migration contexts using SQLAlchemy
+and the target metadata defined in db_async.metadata.
+"""
 import os
 from logging.config import fileConfig
 
 from sqlalchemy import engine_from_config, pool
 from alembic import context
 
-# this is the Alembic Config object, which provides
-# access to the values within the .ini file in use.
+    # Alembic Config object provides access to values in the .ini file
 config = context.config
 
-# Interpret the DATABASE_URL env var, if set; else fall back to ini file
+  # Override sqlalchemy.url with DATABASE_URL environment variable if provided
 database_url = os.getenv('DATABASE_URL', config.get_main_option('sqlalchemy.url'))
 config.set_main_option('sqlalchemy.url', database_url)
 
-# Interpret log config
+# Set up Python logging according to config file
 if config.config_file_name is not None:
     fileConfig(config.config_file_name)
 
@@ -23,7 +27,7 @@ target_metadata = metadata
 
 
 def run_migrations_offline():
-    '''Run migrations in 'offline' mode.'''  # noqa
+    """Run migrations in 'offline' mode using literal SQL script generation."""
     url = config.get_main_option('sqlalchemy.url')
     context.configure(
         url=url,
@@ -37,7 +41,7 @@ def run_migrations_offline():
 
 
 def run_migrations_online():
-    '''Run migrations in 'online' mode.'''  # noqa
+    """Run migrations in 'online' mode against a live database connection."""
     connectable = engine_from_config(
         config.get_section(config.config_ini_section),
         prefix='sqlalchemy.',