dbwarden-redis

Redis-backed distributed migration locking for DBWarden.

When multiple application replicas could trigger migrations concurrently, this plugin provides a Redis-based distributed lock that ensures only one migration process runs at a time across all instances.

Installation

dbwarden plugin add dbwarden-redis

Or manually:

pip install dbwarden-redis

Usage

Async (FastAPI, etc.)

from redis.asyncio import Redis
from dbwarden_redis import migration_lock

redis = Redis.from_url("redis://localhost:6379")

async with migration_lock(redis):
    # Only one migration process runs at a time
    await run_migration()

Sync (CLI, scripts)

from redis import Redis
from dbwarden_redis import sync_migration_lock

redis = Redis.from_url("redis://localhost:6379")

with sync_migration_lock(redis):
    run_migration()

Options

async with migration_lock(
    redis,
    key="my_custom_lock",  # Redis key (default: "dbwarden_migrate")
    ttl=120,  # Lock TTL in seconds (default: 60)
):
    await run_migration()

How it works

1. Acquire: SET key token NX EX ttl (atomic; fails if key already exists)
2. Hold: The lock is held for the duration of the context manager
3. Release: A Lua script deletes the key only if the current caller still owns the token (safe against TTL expiry and concurrent acquisition)

If the process crashes while holding the lock, Redis releases it automatically after the TTL expires.

Database lock vs Redis lock

Both locks can be used independently or together. The database lock protects the CLI; the Redis lock protects any entry point you wrap.

License

MIT