OpenWRT Home Server - Backup and Restore

Overview

After completing OpenWRT Home Server - Installation and Configuration we want to make sure that we can backup and restore our OpenWRT router with ease. It will allow us to continue through the series with a bit of confidence, giving us more freedom to experiment.

This how to is useful to anyone wanting to backup an OpenWRT router, even if you are not following along with this series.

Details

The following should be backed up on all systems:

Installed packages.
Configuration files.

Installed packages

Here we back up a list of installed packages. The credit goes to Upgrade OpenWRT and reinstalling packages for the idea on how to handle this.

Backing up list of installed packages

Make sure to run this before baking up the configuration files, covered in a section below.

root@homesrv:~# opkg list-installed > /etc/config/installed.packages

Restoring installed packages

The router will need access to the Internet before being able to install packages. Assuming that there is a path out:

root@homesrv:~# opkg update
root@homesrv:~# opkg install \
   $(cut -f 1 -d ' ' < /etc/config/installed.packages)

Configuration files

OpenWRT uses sysupgrade to backup configuration files. sysupgrade is used for both LuCI web admin and command line backups, so it is important to configure it correctly.

WARNING: The OpenWRT sysupgrade backup system has to be configured correctly or else files will be missed during backup. Throughout this series, I will do my best to point out when sysupgrade needed to be informed of a new configuration file to backup. In the end it is your responsibility to keep sysupgrade configured correctly.

Configuring sysupgrade

sysupgrade determines which configuration files to backup by:

Using a list of modified configuration files provided by opkg, this list can be viewed by using the opkg list-changed-conffiles command.
Reading the list of file names in /etc/sysupgrade.conf, an example can be found here: sysupgrade.conf.

On the router, comb through the output of opkg list-changed-conffiles and check for missing entries:

$ ssh root@192.168.1.1
root@homesrv:~# opkg list-changed-conffiles | sort -u

If you completed OpenWRT Home Server - Installation and Configuration, you might notice that /etc/dropbear/authorized_keys is missing. /etc/config/installed.packages from above should be added as well. Update the sysupgrade configuration with vi /etc/sysupgrade.conf and add it. The contents of /etc/sysupgrade.conf should look something like:

## This file contains files and directories that should
## be preserved during an upgrade.

# /etc/example.conf
# /etc/openvpn/
/etc/sysupgrade.conf
/etc/config/installed.packages

OpenWRT comes with a minimalistic vi application that is part of BusyBox.

Backing up configuration files

Create the backup in the /tmp/ directory. /tmp/ is actually an in memory file system (RAM). Backing up to anywhere else would likely fill up the already limited space on the router, as well as increase the wear on the flash.

root@homesrv:~# sysupgrade -v --create-backup \
    /tmp/backup-$(cat /proc/sys/kernel/hostname)-$(date +%F).tgz

Next you should confirm that backup exists and contains the expected files:

root@homesrv:~# ls -l /tmp/backup-*-$(date +%F).tgz
root@homesrv:~# tar -zvtf /tmp/backup-*-$(date +%F).tgz

Copy the backup file off of the router and put it somewhere safe, scp to your workstation might be a good option. The remove the backup file once it has been copied off of the router to free up space:

root@homesrv:~# rm /tmp/backup-*-$(date +%F).tgz

Restoring configuration files

scp the backup file into the /tmp/ directory on the router, then:

root@OpenWrt~# sysupgrade -v --restore-backup /tmp/backup-*.tgz
root@OpenWrt~# reboot

Workflows

Some general workflows on how to backup and restore a router with OpenWRT.

Backup workflow

Backup list of installed packages.
Backup configuration files.
Copy the backup file off of the router and put it in a safe place.
Delete the backup file from /tmp/ on the router.

Restore workflow

For a simple, configuration only restore:

Copy the backup file to the /tmp/ director on the router.
Restore installed packages.
Reboot the router.

If you lost everything, configuration files and installed packages (this happens after a factory reset):

First get the router connected to the Internet again. You can untar the backup file on your workstation and pull the information you need from there.
Once connected to the Internet, copy installed.packages to /tmp/ on the router. The Restore installed packages.
Copy the backup file to the /tmp/ director on the router.
Restore configuration files.
Reboot the router.

Backup and restore through the web interface

And, of course, backups and restores can be performed through the administrative web interface. The page can be found through the System -> Backup / Flash Firmware menu.

Backups through the web admin site do not include a list of installed packages, that will still have to be done manually. /etc/sysupgrade.conf still has to be updates to pick up missing files, as described in Configuring sysupgrade.

Advanced backup and restore

For those that want to do a full backup of the flash, read OpenWRT Generic Backup.

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