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https://github.com/llucax/bacap

An extremely simple - yet configurable - backup script
https://github.com/llucax/bacap

backup bash rsync rsync-backup script

Last synced: 11 months ago
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An extremely simple - yet configurable - backup script

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README 

          
.. -*- restructuredtext -*-



==========================================

Bacap - The extremely simple backup script

==========================================



:Author: Leandro Lucarella

:Contact: luca@llucax.com

:Copyright: Leandro Lucarella (2010), released under the BOLA_ license



.. _BOLA: http://blitiri.com.ar/p/bola/



About

=====



Bacap_ is a very simple script (~100 SLOC_ of Bash_) to do an incremental backup

that saves space using rsync_ and hard-links. Is not the first, and it probably

will not be the last, so why should you use precisely this one? I have **no**

idea. All I can tell you is:



1. I did it, so it has to be great!

2. Is very simple, meaning is very easy to understand and customize.

3. You can backup multiple hosts.



Did I mention is very simple? I guess that is the only selling point, so

remember: **It's very simple** =)



.. _Bacap: https://github.com/llucax/bacap/

.. _SLOC: http://en.wikipedia.org/wiki/Source_lines_of_code

.. _Bash: http://www.gnu.org/software/bash/

.. _rsync: http://rsync.samba.org/



Installation

============



Doing something very complex in ~100 SLOC_ is not easy, unless you're standing

in the shoulders of giants. I'm standing in the shoulders of rsync_ mainly, so

you should install it before using the script. You will need a bunch of `basic

POSIX commands`__, like ``date``, ``dirname``, ``readlink``, ``basename``,

``cat``, ``awk``, etc.; and ``crontab`` if you don't want to run the script

manually each time you remember to actually do a backup; but I'm sure you

already have those.  And of course, Bash_, but again, I'm sure you have it too.

If you want to backup remote hosts, be sure ssh_ is installed too.



__ http://www.opengroup.org/onlinepubs/009695399/utilities/toc.html

.. _ssh: http://www.openssh.com/



Once you have it all, just `download the script`__ from the git_ repo__ and copy

it to wherever you like. Set the executable bit if appropriate::



	chmod a+x bacap



__ https://raw.githubusercontent.com/llucax/bacap/main/bacap

__ https://github.com/llucax/bacap

.. _git: http://git-scm.com/



Configuration

=============



If you don't like the defaults (you probably wont), you can add a configuration

file. Configuration files are searched in this places:



1. ``/etc/bacaprc``

2. ``/etc/bacap/bacaprc``

3. ``bacaprc`` in the same directory as the ``bacap`` script

4. Optional parameter passed as argument to the script

5. ``$CONFIG_PATH/$HOST/bacaprc``



Order is important, since all files are read (if possible) and values in the

last configuration file read overwrites old values. The script takes an optional

parameter, which is another location to look for a configuration file. If the

configuration file passed as argument can't be found, an error will be printed

(no error is issued if any of the other configuration files are missing).

Also, config options could be specified on a per host basis by creating a

``bacaprc`` file in ``$CONFIG_PATH/$HOST``. As a side effect of this,

configuration file(s) are read initially and each time the script backups a new

host. So the configuration file(s) are read at least two times even if you

backup one host.



The configuration file is a Bash_ script too, you can see the `default values

in the script`__.



__ https://github.com/llucax/bacap/blob/main/bacap#L4-L44



Once you've created the configuration file(s), you should create the directory

``$CONFIG_PATH`` (meaning, the value you used for that variable in the

configuration file)::



	mkdir -p $CONFIG_PATH



Then create a directory for each host you want to backup there, the directory

name should be the name of the host (as you would use to connect to it using

ssh_). For now let's say we will only backup ``localhost``::



	mkdir $CONFIG_PATH/$LOCALHOST



You should be able to guess what ``$LOCALHOST`` stands for by now =)



Now, you should create at least one file there, ``paths`` which should have one

line for each path to backup in that host. Let's say we want to backup only

``/etc`` and ``/home``::



	echo /etc > $CONFIG_PATH/$LOCALHOST/paths

	echo /home >> $CONFIG_PATH/$LOCALHOST/paths



But sometimes there are things there that you don't want to backup, in that

case you can create a file named ``excludes`` too, and write which paths you

want to exclude there, one path in each line (you can use wildcards and anything

supported by the ``--exclude-from`` rsync_ option). Let's say we don't want to

backup rata's home::



	echo /home/rata/ > $CONFIG_PATH/$LOCALHOST/excludes



Also, if you don't want to exclude files matching some pattern, you can create

a file named ``includes`` with the patterns you want to include (you can use

anything supported by the ``--include-from`` rsync_ option)



That's pretty much it. If you want to add other hosts, just create the host

directory and the needed host configuration files.



Usage

=====



As we said in the configuration section, the only argument the script take is an

extra configuration file. All options are managed through configurations files.



The script creates a new directory in ``$BACKUP_PATH/$host/$date`` and copies

(hard-links) the configured paths for each ``$host``. ``$date`` is the current

date at the time of starting the script, formatted according to ``$DATE_FMT``. By

default this has day *resolution*, but you can add hours, minutes or even

seconds if you want to do more frequent backups. If the directory already exist

for any host, it skips that host.



A symbolic link is created at the end of the backup, with the name

``$BACKUP_PATH/$host/current``, and pointing to the newly created directory.



Tips

====



Here are a few tips on how to configure Bacap_ for several common scenarios.



Automating backups using cron

-----------------------------



You probably want to automate your backup using *cron*. I will not include

a *cron* tutorial here, but if you are completely lost, you can add this line to

``/etc/crontab`` to make a daily backup at 6:30::



	30 6 * * * root /path/to/bacap



If you are a Debian_ user, you can also simply install the script in

``/etc/cron.daily`` (or make a symlink or something similar) and you are set.



.. _Debian: http://www.debian.org/



Providing a ssh_ key

--------------------



When doing a backup of a remote host, you probably want ssh_ to be able to

login without providing a password. To do so, you can generate a ssh_ key using

``ssh-keygen``, copy the public key to the target's

``/root/.ssh/authorized_keys`` using ``ssh-copy-id root@host`` (or the user

that runs the backup) and set the Bacap_ configuration variable ``RSYNC_RSH``

to something like::



	RSYNC_RSH="ssh -i /path/to/priv-key -o NumberOfPasswordPrompts=0"



The ``-o NumberOfPasswordPrompts=0`` is not necessary, but you would appreciate

it if something is wrong with your key, since if you don't use it, rsync_ will

hang asking for a password.



Also, you may consider using ``StrictHostKeyChecking=no`` ssh option if you

backup hosts with dynamic IP address.



Backup local networks nodes (or nodes with a fast connection)

-------------------------------------------------------------



When the bandwidth is not tight, you probably want to ensure ssh_ doesn't use

compression::



	RSYNC_RSH="ssh -o Compression=no"



And if your network is trusted, you probably don't need very strong encryption

either::



	RSYNC_RSH="ssh -o Compression=no -c arcfour"



Listing differences between 2 snapshots

---------------------------------------



If you want to see what have actually changed between two backups you can run

rsync_ with your usual flags plus ``-nv --delete``. For example if you just use

``-a``, to see the differences between ``lolaus/2010-07-11`` and

``lolaus/2010-07-12`` you can run::



        rsync -nav --delete lolaus/2010-07-11/ lolaus/2010-07-12/



Similar alternatives

====================



* Do it yourself: this script was **heavily** inspired by an article__ by `Kevin

  Korb`__ (well, it was really inspired by the `previous version`__ of the

  article =).

* `Back In Time`__: Nice looking graphical alternative.

* `rsnapshot`__: A more mature and heavier alternative. I didn't really used it

  though, so I can't say much.



__ http://www.sanitarium.net/golug/rsync_backups_2010.html

__ http://www.sanitarium.net/

__ http://www.sanitarium.net/golug/rsync_backups_2005.html



__ http://backintime.le-web.org/



__ http://rsnapshot.org/



I'm sure there are plenty of others, if you have one and want to be listed here,

please feel free to `drop me an e-mail`__.



__ mailto:luca@llucax.com