rs-backup-suite

rs-backup-suite is a set of shell scripts for setting up a custom NAS on a computer in the network. It uses rsync and rsnapshot.

How it works

rs-backup-suite is designed for push backups, which means the client pushes its files to the server. This is ideal for computers which are not always on such as most desktop PCs.

It is also a user-centric backup system. That means each user creates his own backup on the NAS instead of root backing up the whole machine at once (although this is possible). That also means that each user has a UNIX account on the NAS. The NAS username is usually <hostname>-<local user name> (e.g. mymachine-johndoe).

On the client machine(s) each user can create a file called .rs-backup-include (name is configurable) inside his home directory which includes the list of files that should be considered by the backup. Additionally root can maintain a similar file located at /usr/local/etc/rs-backup/include-files for the system files.

Setup (please read this carefully before performing any actions!)

rs-backup-suite is split into two parts: a client part for pushing the backup to the NAS and a server part which runs on the NAS itself.

Server

For installing the server component run

sudo ./install.sh server

on your server machine. This installs all the necessary files into the right location on your system.

Tweaking the configuration file

If you need to tweak the server settings, simply edit /etc/rs-backup/server-config to your needs. There you can configure the following directives:

• BACKUP_ROOT: The directory under which the home directories of the backup users are stored. The default is /bkp
• FILES_DIR: The directory under which the actual backups are kept (relative to the backup user's home directory). The default is files.
• SET_QUOTA: Whether to set disk quota for the users or not (for Ext3/4 file systems). Default is false.
• QUOTA_SOFT_LIMIT, QUOTA_HARD_LIMIT, QUOTA_INODE_SOFT_LIMIT, QUOTA_INODE_HARD_LIMIT: The individual limits for disk quota. Ignored, if SET_QUOTA is false.

WARNING: Adjust these settings before you create backup users, because they won't be re-applied for already existing users!

Adding a backup user

A backup user is an unprivileged UNIX account on the server. Normally each user on each client has one corresponding backup user which he uses to log into the NAS. A backup user can be created by running

rs-add-user hostname username [ssh-public-key-file]

on the server where hostname is the name of the client host and username is the name of the user on that machine for whom this account is made. Of course you can use any other names for hostname and username as well, but it's generally a good idea to stick to this naming convention. The resulting UNIX username will be the combination of both.

The optional third parameter specifies the path to the SSH public key file which the user will use to log into the NAS. If you don't specify it, the user won't be able to log in at all. But you can add one later at any time by running

rs-add-ssh-key hostname username ssh-public-key-file

hostname and username are the same as above and mandatory for identifying the user that should get the new key.

TIP: If you don't remember the parameters for all these commands, simply run them without any and you'll get simple usage instructions.

Making the chroot work

rs-backup-suite can chroot backup users into the backup home base directory. For this to work you need to create a few bind mounts. The install script already created the respective lines in your /etc/fstab for you. If you don't need any special configuration on your system, all you need to do is to uncomment everything between the BEGIN and END lines (do NOT change these two lines, though):

# BEGIN: rs-backup-suite
#/lib                    /bkp/lib                 none    bind             0       0
#/dev                    /bkp/dev                 none    bind             0       0
#/usr/bin                /bkp/usr/bin             none    bind             0       0
#/usr/lib                /bkp/usr/lib             none    bind             0       0
#/usr/share/perl5        /bkp/usr/share/perl5     none    bind             0       0
# END: rs-backup-suite

The necessary mounts may differ from system to system. For instance, Ubuntu needs /usr/share/perl instead of /usr/share/perl5. Synology DSM doesn't need /usr/share/* at all, but requires /opt/bin, /opt/lib and /opt/libexec. But in most cases you don't need to worry about that since the install script tries to make the correct decisions for you.

NOTE: If your 64-bit system doesn't have a /lib folder but only /lib64 you may need to change the /lib line in your /etc/fstab as follows:

/lib64                  /bkp/lib64               none    bind             0       0

Don't forget to rename /bkp/lib to /bkp/lib64.

When you're done, add this to the end of your /etc/ssh/sshd_config:

Match Group backup 
    ChrootDirectory /bkp/

and restart OpenSSH. Your backup users are now chrooted into /bkp.

NOTE: When using a chroot environment and you change anything in your user configuration (e.g. the username) you need to run rs-update-passwd or your user might not be able to log in anymore.

Changing the rotation options/backup levels

To change how many increments of which level are kept, edit the file /bkp/etc/rsnapshot.global.conf. This is the global configuration file for rsnapshot which will be included in each user-specific configuration. There you can tweak the names and numbers for all backup levels.

If you add or remove any backup levels, make sure you also update the cron scripts. By default three cron scripts are installed: /etc/cron.daily/rs-backup-rotate, /etc/cron.weekly/rs-backup-rotate and /etc/cron.monthly/rs-backup-rotate.

Client

To set up the client you simply need to run

sudo ./install.sh client

on your client machine. Then open the file /etc/rs-backup/client-config as root and replace the value of REMOTE_HOST with the hostname or IP address of your NAS.

On the client machines the script /usr/bin/rs-backup-run is used for performing the backups. This script can either be run as root or as an unprivileged user. The behavior differs in both cases:

• If run as root, all files and folder specified in /etc/rs-backup/include-files will be backed up. The backup user used for logging into the NAS is hostname-root by default (where hostname is the hostname of the current machine). Additionally the home directories of all users will be scanned. If a home directory contains a file called .rs-backup-include all files and folders specified inside that file will be backed up under this user's privileges. The username used for logging into the NAS is hostname-username (where hostname is again substituted for the hostname of the current machine and username for the user whose home directory is being backed up).
• If run as a normal user, only the files that are specified in your own .rs-backup-include will be backed up.

Changing the default configuration

All the client configuration options are defined in /etc/rs-backup/client-config. You can edit the file as you wish. All parameters are documented clearly by comments. Most of these configuration options can also be overridden at runtime by passing command line arguments to rs-backup-run. For a list and a description of all possible command line arguments run

rs-backup-run --help

Installing client and server on the same machine

You can of course also install server and client on the same machine. This may be useful if you want, e.g. save your data to an external USB drive instead of a real NAS. A shortcut for running both sudo ./install server and sudo ./install client is simply running

sudo ./install all

Uninstalling

For uninstalling run

./uninstall.sh [all|server|client]

This removes all the scripts but preserves the data in /bkp (or whatever your backup folder is).

Backup strategies

The intended use case for rs-backup-suite is as follows: you set up the server part on your NAS. Then you create a backup user for each user on each client machine.

In the next step you edit the crontab for root on each client and add a job for running /usr/bin/rs-backup-run at certain times. You can of course also create a shell script that calls rs-backup-run and put it in /etc/cron.daily to perform a global backup once a day.

After everything is set up that way you create the file /etc/rs-backup/include-file and write to it a list of files and folders you want to back up as root (e.g. you can specify /etc/*** to backup the whole /etc directory and all its subdirectories). Furthermore each user creates a file called .rs-backup-include inside his home directory that serves the same purpose for his own home directory instead of the global system. Such a file could look like this:

- /home/johndoe/.cache/***
/home
/home/johndoe/***

Lines that start with a - are treated as excludes, all other lines as includes. The three asterisks mean “Include this directory and everything below”. For more information about these globbing patterns read the FILTER RULES section of the rsync(1) man page.

NOTE: To include a directory you need to mark all parent directories for inclusion, too. For instance to include /home/johndoe you also need to include /home as shown above. But don't confuse /home with /home/! /home without the trailing slash only selects the (empty) directory itself, not its contents.

Restoring files from the NAS

To restore files from the NAS server simply run:

rsync -a -e ssh backupuser@remotehost::pull/source/path /destination/path

Replace backupuser with the proper backup user (e.g. mymachine-johndoe) and remotehost with the hostname of the NAS. /source/path is the file name on the remote side (e.g. /daily.2/home/johndoe/foobar) and /destination/path is the local destination file name.

You can also log into the NAS using SFTP or SSHFS. This is probably more convenient for browsing available files.

Be aware that both access methods are strictly read-only! Write access is only granted via rsync through the push module:

rsync -a -e ssh backupuser@remotehost::push/destination/path /source/path

Side note

Because rs-backup-suite uses rsync for the client-server communication you don't necessarily need both parts. As long as you have a working rsync server on your NAS you can use the client script to push files to it. On the other hand you can use the rs-backup-suite server part with any other rsync client, as well.

Warning to users of older versions

rs-backup used to reside in /usr/local instead of /usr. With the addition of a proper Makefile in version 0.2.0 this has changed. The consequence is that older setups won't work with the new version without modifications. In order to update your setup you need to update the path to rs-run-ssh-cmd (now at /usr/bin/rs-run-ssh-cmd) inside your users' ~/.ssh/authorized_keys files as well as the path to rs-rotate (/usr/bin/rs-rotate) inside their rsync.conf files. Alternatively just create symlinks to the old locations.

Moving rs-backup to /usr also means that for chroot setups the /bkp/usr/local mountpoint is no longer needed.