bak - backup script

About

bak is a python backup script that utilizes rsync and hardlinks for efficient and convenient backups. Furthermore, backup rotation is achieved through simple expiration rules.

How It Works

This script utilizes rsync to backup any number of specified directories on other hosts to a local machine. You specify host, source, destination, and other options in the /etc/bak.conf file. Here is an example:

[mail.example.com]
host=mail.example.com
sources=/var /etc /home
dest=/pub/bak

When added to a daily cronjob, this will cause the /var, /etc, and /home directories on mail.example.com to be incrementally backed up to the /pub/bak/mail.example.com/date/ directory. rsync will use hard-links to ensure that only a single copy of all unchanged files are saved to disk. You can cd into the backup directory at anytime and see your files.

You can also specify backup rotation parameters in the /etc/bak.conf to control when backups expire. The default is 

num_days=14
num_weeks=10
num_months=12
num_years=10

This means that incremental backups for the last 14 days will be saved. Furthermore, the Sunday backup for the last 10 weeks will also be preserved as well as the first Sunday backup of each month for the last 12 months. Lastly, the first Sunday backup of the year will be preserved for 10 years.

Download

bak-0.14.tar.gz
Alternatively, browse the git repo or clone it 

git clone http://brooks.nu/git/bak

RPM is also available.

Install

  1. Untar the source

    tar xzvf tar-XXX.tar.gz
  2. Run the installation command 
    make install
  3. Edit the /etc/bak.conf to setup your backups.

The install script will put the script called bak in your /usr/sbin/ directory. It will also put a sym-link to this executable in your /etc/cron.daily directory. This will make the backup script run daily. You can instead remove the sym-link and add the script to your crontab.

SSH keys

As root, or whichever user your cronjob will run as, you will want to setup ssh keys so this script can run without human intervention to type in the password. Setting up ssh keys is simple.

  1. Create your keys 
    ssh-keygen

    Select an empty passphrase and choose the default location

  2. Put the id_rsa.pub file in your authorized key file: 
    cd ~/.ssh
cat id_rsa.pub >> authorized_keys
  3. Copy the id_rsa.pub, id_rsa, and authorized_keys file to all your hosts. 
    scp id_rsa id_rsa.pub authorized_keys host.example.com:.ssh/
  4. Test it out to see that you can ssh around without typing in your password.