MongoDB PITR: Restoring to the Second with Oplog Replay
db.collection.drop() at 4 PM means you lose an entire day of production data. To solve this, I put together an open-source Point-in-Time Recovery (PITR) system that combines oplog replay with Docker and Google Drive for offsite storage.
The core logic relies on the MongoDB oplog (operations log). By capturing these writes in real-time and shipping them to a secure cloud location, you can restore a full backup and then "replay" every single transaction up to the exact millisecond before the mistake happened.
Here is the high-level architecture for this deployment:
1. Oplog Tailing: A sidecar container monitors the MongoDB oplog.
2. Incremental Backups: Instead of dumping the whole DB, the system continuously streams the oplog entries.
3. Cloud Sync: These logs are pushed to Google Drive to ensure the backups aren't sitting on the same disk as the database.
4. Recovery Process: To restore, you deploy the last full snapshot and run the oplog replay tool to catch up to the desired timestamp.
For those setting this up from scratch, make sure your MongoDB is running as a Replica Set (even if it's a single-node set), otherwise, the oplog isn't enabled and PITR is impossible.
If you're looking for the full implementation details, the project is hosted here:
https://dev.to/takiuddinahmed/how-i-built-a-mongodb-backup-system-that-can-undo-an-accidental-drop-2l51