quartermaster/alembic/env.py

import subprocess
from logging.config import fileConfig
from pathlib import Path

from sqlalchemy import engine_from_config, pool

from alembic import context

from quartermaster.config import DB_URL
from quartermaster.models import Base


def _backup_before_migrations() -> None:
    script = Path(__file__).resolve().parents[1] / "scripts" / "backup-db.sh"
    if not script.is_file():
        return
    result = subprocess.run(
        [str(script), "alembic"],
        check=False,
        capture_output=True,
        text=True,
    )
    if result.stdout:
        print(result.stdout, end="")
    if result.returncode != 0 and result.stderr:
        print(
            f"alembic: backup-db.sh returned {result.returncode}; "
            f"continuing without a fresh backup.\n{result.stderr}",
        )


_backup_before_migrations()

config = context.config
config.set_main_option("sqlalchemy.url", DB_URL)

if config.config_file_name is not None:
    fileConfig(config.config_file_name)

target_metadata = Base.metadata


def run_migrations_offline() -> None:
    url = config.get_main_option("sqlalchemy.url")
    context.configure(
        url=url,
        target_metadata=target_metadata,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
        render_as_batch=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:
        context.configure(
            connection=connection,
            target_metadata=target_metadata,
            render_as_batch=True,
        )
        with context.begin_transaction():
            context.run_migrations()


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