# `btrfs` Backup Solution

Encrypted incremental backups utilizing
[`btrfs send`](https://btrfs.wiki.kernel.org/index.php/Manpage/btrfs-send)
and [`age`](https://age-encryption.org/).

## Setup

At `/media/storage/backup`, we have:

```
backup/
  data/ [a btrfs **subvolume** containing the data]
    ...
  snapshots/ [btrfs snapshots of the 'data' subvolume]
  repo/ [where encrypted backup files will go]

  [an age-encryption v1 key for the at-rest passphrase]
  static-passphrase-key
  static-passphrase-key.pub

  [the contents of this repo:]
  backup.sh
  create-passphrase-file.sh
```

You can generate the `static-passphrase-key` and `static-passphrase-key.pub` with
`rage-keygen -o static-passphrase-key` and by manually populating the pubkey file.

## Requirements

**Note:** Make sure that `data` is actually a btrfs subvolume!!

- `btrfs`
- `bash`
- `zstd`
- [`rage`](https://github.com/str4d/rage)
- [`simple-age-encryptor`](https://git.lavender.software/charlotte/simple-age-encryptor)