This chapter will get you started with
Attic. The first section
presents a simple step by step example that uses
Attic to backup data.
The next section continues by showing how backups can be automated.
A step by step example¶
Before a backup can be made a repository has to be initialized:
$ attic init /somewhere/my-repository.attic
~/Documentsdirectories into an archive called Monday:
$ attic create /somewhere/my-repository.attic::Monday ~/src ~/Documents
The next day create a new archive called Tuesday:
$ attic create --stats /somewhere/my-repository.attic::Tuesday ~/src ~/Documents
This backup will be a lot quicker and a lot smaller since only new never before seen data is stored. The
Atticto output statistics about the newly created archive such as the amount of unique data (not shared with other archives):
Archive name: Tuesday Archive fingerprint: 387a5e3f9b0e792e91ce87134b0f4bfe17677d9248cb5337f3fbf3a8e157942a Start time: Tue Mar 25 12:00:10 2014 End time: Tue Mar 25 12:00:10 2014 Duration: 0.08 seconds Number of files: 358 Original size Compressed size Deduplicated size This archive: 57.16 MB 46.78 MB 151.67 kB All archives: 114.02 MB 93.46 MB 44.81 MB
List all archives in the repository:
$ attic list /somewhere/my-repository.attic Monday Mon Mar 24 11:59:35 2014 Tuesday Tue Mar 25 12:00:10 2014
List the contents of the Monday archive:
$ attic list /somewhere/my-repository.attic::Monday drwxr-xr-x user group 0 Jan 06 15:22 home/user/Documents -rw-r--r-- user group 7961 Nov 17 2012 home/user/Documents/Important.doc ...
Restore the Monday archive:
$ attic extract /somwhere/my-repository.attic::Monday
Recover disk space by manually deleting the Monday archive:
$ attic delete /somwhere/my-backup.attic::Monday
Attic is quiet by default. Add the
--verbose option to
get progress reporting during command execution.
The following example script backs up
/var/www to a remote server. The script also uses the
attic prune subcommand to maintain a certain number
of old archives:
#!/bin/sh REPOSITORYfirstname.lastname@example.org:repository.attic # Backup all of /home and /var/www except a few # excluded directories attic create --stats \ $REPOSITORY::hostname-`date +%Y-%m-%d` \ /home \ /var/www \ --exclude /home/*/.cache \ --exclude /home/Ben/Music/Justin\ Bieber \ --exclude '*.pyc' # Use the `prune` subcommand to maintain 7 daily, 4 weekly # and 6 monthly archives. attic prune -v $REPOSITORY --keep-daily=7 --keep-weekly=4 --keep-monthly=6
Repository encryption is enabled at repository creation time:
$ attic init --encryption=passphrase|keyfile PATH
All data is encrypted before being written to the repository. This means that an attacker that manages to compromise the host containing an encrypted archive will not be able to access any of the data.
Attic supports two different methods to derive the AES and HMAC keys.
- Passphrase based encryption
This method uses a user supplied passphrase to derive the keys using the PBKDF2 key derivation function. This method is convenient to use since there is no key file to keep track of and secure as long as a strong passphrase is used.
For automated backups the passphrase can be specified using the ATTIC_PASSPHRASE environment variable.
- Key file based encryption
This method generates random keys at repository initialization time that are stored in a password protected file in the
~/.attic/keys/directory. The key file is a printable text file. This method is secure and suitable for automated backups.
The repository data is totally inaccessible without the key file so it must be kept safe.
Attic can initialize and access repositories on remote hosts if the
host is accessible using SSH. This is fastest and easiest when
is installed on the remote host, in which case the following syntax is used:
$ attic init user@hostname:repository.attic
$ attic init ssh://user@hostname:port/repository.attic
If it is not possible to install
Attic on the remote host,
it is still possible to use the remote host to store a repository by
mounting the remote filesystem, for example, using sshfs:
$ sshfs user@hostname:/path/to/folder /tmp/mymountpoint $ attic init /tmp/mymountpoint/repository.attic $ fusermount -u /tmp/mymountpoint
However, be aware that sshfs doesn’t fully implement POSIX locks, so you must be sure to not have two processes trying to access the same repository at the same time.