View source for btrbk

[http://digint.ch/btrbk/ btrbk] is a backup tool for [[Btrfs]] disks.

{{WIP}}

== Setup Server ==
The backup server will be the machine that will receive the backup data. Clients will connect to it to sent their backup data. As a consequence, your server must be reachable from all your clients.

=== Destination Disk ===
Create a Btrfs volume or subvolume and mount it on <code>/backup</code>.

=== User ===
<syntaxhighlight lang="console">
$ sudo adduser --system --shell /bin/sh --home /backup/ --group --no-create-home btrbk
Adding system user `btrbk' (UID 122) ...
Adding new group `btrbk' (GID 124) ...
Adding new user `btrbk' (UID 122) with group `btrbk' ...
Not creating home directory `/backup/'.
$ sudo mkdir /backup/.ssh
$ sudo touch /backup/.ssh/authorized_keys
$ sudo chown root:btrbk /backup/
$ sudo chmod 710 /backup/
</syntaxhighlight>
This user will need to run <code>btrfs</code> tools as root. Let’s add this to the <code>/etc/sudoers</code> file
<syntaxhighlight lang="sh">
btrbk   ALL=NOPASSWD:/bin/btrfs
</syntaxhighlight>If you limited access to certain users through SSH, add <code>btrbk</code> to the [[SSH#Authentication|AllowUsers]] list and [[SSH#Restart|restart SSH]]

== Setup Client ==

=== Install btrbk ===
btrbk is not yet included in Debian Jessie. Make sure you configure [[Apt|stretch source]] before running the command bellow.<syntaxhighlight lang="console">
$ sudo apt install btrbk
</syntaxhighlight>

=== SSH Key ===
Create an SSH key dedicated to your backups<syntaxhighlight lang="console">
$ sudo mkdir /etc/btrbk/ssh
$ sudo chmod 700 /etc/btrbk/ssh
$ sudo ssh-keygen -t ed25519 -N "" -f /etc/btrbk/ssh/id_ed25519
Generating public/private ed25519 key pair.
Your identification has been saved in /etc/btrbk/ssh/id_ed25519.
Your public key has been saved in /etc/btrbk/ssh/id_ed25519.pub.
The key fingerprint is:
SHA256:y5VremJsz5wHiO2KKrtupPZYbaqNeURxeLdznaCw450 root@client.example.org
The key's randomart image is:
+--[ED25519 256]--+
|    .            |
|   o + . .       |
|    + + o o .    |
|   . o + . +     |
|  . . ooS.o      |
| . ....Eoo..     |
|o .. o oo o.     |
|oo*.o.  *=...    |
|*X==. .+.+=.     |
+----[SHA256]-----+
$ sudo cat /etc/btrbk/ssh/id_ed25519.pub
AAAAC3NzaC1lZDI1NTE5AAAAIB5ScAgJnpqYCipj6PyrOjbXpsaQZIzys7uHcVe1J3ay root@client.example.org
</syntaxhighlight>Keep the result of the last command, you will need it at the next step.

=== Register Client on the Server ===
'''Note:''' On the instructions bellow, the token <code><client></code> must be replace by the machine name.

==== Create Destination Folder ====
'''On the backup server''', create a new folder for the client.<syntaxhighlight lang="console">
$ sudo mkdir /backup/<client>
$ sudo chmod 700 /backup/<client>
</syntaxhighlight>
==== Setup SSH Key ====
Then, '''on the backup server''', add the following line to <code>/backup/.ssh/authorized_keys</code>. The key at the end of the line must be replaced with the public key that you created above.

If you have OpenSSH 7.2 or above (test using <code>ssh -V</code>), use this line<syntaxhighlight lang="sh">
command="/usr/share/btrbk/scripts/ssh_filter_btrbk.sh --target --info -p /backup/<client> --sudo",restrict ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIB5ScAgJnpqYCipj6PyrOjbXpsaQZIzys7uHcVe1J3ay root@client.example.org
</syntaxhighlight>Otherwise, you need the more verbose version<syntaxhighlight lang="sh">
command="/usr/share/btrbk/scripts/ssh_filter_btrbk.sh --target --info -p /backup/<client> --sudo",no-agent-forwarding,no-port-forwarding,no-pty,no-user-rc,no-X11-forwarding ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIB5ScAgJnpqYCipj6PyrOjbXpsaQZIzys7uHcVe1J3ay root@client.example.org
</syntaxhighlight>

=== Configure btrbk ===
Create file <code>/ect/btrbk/btrbk.conf</code><syntaxhighlight lang="properties">
# Enable transaction log
transaction_log             /var/log/btrbk.log

# Directory in which the btrfs snapshots are created. Relative to
# <volume-directory> of the volume section.
# If not set, the snapshots are created in <volume-directory>.
#
# If you want to set a custom name for the snapshot (and backups),
# use the "snapshot_name" option within the subvolume section.
#
# NOTE: btrbk does not autmatically create this directory, and the
# snapshot creation will fail if it is not present.
#
snapshot_dir                _btrbk_snap


# Specify SSH private key for "ssh://" volumes / targets:
ssh_identity                /etc/btrbk/ssh/id_ed25519
ssh_user                    btrbk
#ssh_port                   default
#ssh_compression            no
#ssh_cipher_spec            default

# Don't wait for transaction commit on deletion. Set this to "after"
# or "each" to make sure the deletion of subvolumes is committed to
# disk when btrbk terminates.
#btrfs_commit_delete        no

# Set this to "yes" to enable btrfs-progs < 3.17 compatibility.
# Set this either globally or in a specific "target" section.
#btrfs_progs_compat         no

snapshot_preserve_min 5d
snapshot_preserve     14d 2w 1m

target_preserve_min 5d
target_preserve     14d 10w 24m

#
# Volume section: "volume <volume-directory>"
#
#   <volume-directory>  Directory of a btrfs volume (or subvolume)
#                       containing the subvolume to be backuped
#                       (usually the mount-point of a btrfs filesystem
#                       mounted with subvolid=0 option)
#
# Subvolume section: "subvolume <subvolume-name>
#
#   <subvolume-name>    Subvolume to be backuped, relative to
#                       <volume-directory> in volume section.
#
# Target section: "target <type> <volume-directory>"
#
#   <type>              Backup type, currently only "send-receive".
#   <volume-directory>  Directory of a btrfs volume (or subvolume)
#                       receiving the backups.
#
# NOTE: The parser does not care about indentation, this is only for
# human readability. The options always apply to the last section
# encountered, overriding the corresponding option of the upper
# section. This means that the global options must be set before any
# "volume" section.
#

</syntaxhighlight>

== Add a Backup Volume ==
<syntaxhighlight lang="console">
$ sudo btrfs subvolume create /backup/<client>/<volume>
</syntaxhighlight>{{TODO|msg = }}

[[Category:Debian Release]]
[[Category:Linux Desktop]]
[[Category:Linux Server]]