canned-prompts/service/migrations/env.py

"""Alembic environment.

The database URL comes from settings, never from alembic.ini, so a migration
cannot be run against a different database than the service uses.
"""

from __future__ import annotations

from alembic import context
from sqlalchemy import engine_from_config, pool

from canned_prompts_service.db import Base, assume_owner_role
from canned_prompts_service.settings import get_settings
from canned_prompts_service import models  # noqa: F401 — registers the tables

config = context.config
target_metadata = Base.metadata

settings = get_settings()
if settings.configured:
    # resolved_database_url, not database_url: in the cluster the credential
    # arrives as a mounted file and the plain field is empty.
    #
    # The value is escaped because set_main_option interpolates through
    # ConfigParser, so a `%` in a generated password would otherwise raise —
    # at credential rotation, which is the worst time to discover it.
    config.set_main_option(
        "sqlalchemy.url", settings.resolved_database_url.replace("%", "%%")
    )


def run_migrations_offline() -> None:
    context.configure(
        url=config.get_main_option("sqlalchemy.url"),
        target_metadata=target_metadata,
        literal_binds=True,
    )
    with context.begin_transaction():
        context.run_migrations()


def run_migrations_online() -> None:
    connectable = engine_from_config(
        config.get_section(config.config_ini_section, {}),
        prefix="sqlalchemy.",
        poolclass=pool.NullPool,
    )
    with connectable.connect() as connection:
        assume_owner_role(connection)
        context.configure(connection=connection, target_metadata=target_metadata)
        with context.begin_transaction():
            context.run_migrations()
        # Belt and braces: if anything else ever touches this connection before
        # Alembic, the same nesting trap reappears silently.
        connection.commit()


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