BorgServer - Docker image

Debian based container image, running openssh-daemon only accessable by user named "borg" using SSH-Publickey Auth & "borgbackup" as client. Backup-Repositoriees, client's SSH-Keys & SSHd's Hostkeys will be stored in persistent storage. For every ssh-key added, a own borg-repository will be created.

NOTE: I will assume that you know, what a ssh-key is and how to generate & use it. If not, you might want to start here: Arch Wiki

Quick Example

Here is a quick example how to configure & run this image:

Create persistent sshkey storage

 $ mkdir -p borg/sshkeys/clients

Make sure that the permissions are right on the sshkey folder:

 $ chown 1000:1000 borg/sshkeys

(Generate &) Copy every client's ssh publickey into persistent storage

Remember: Filename = Borg-repository name!

 $ cp ~/.ssh/my_machine.pub borg/sshkeys/clients/my_machine

The OpenSSH-Deamon will expose on port 22/tcp - so you will most likely want to redirect it to a different port. Like in this example:

docker run -td \
			-p 2222:22  \
			--volume ./borg/sshkeys:/sshkeys \
			--volume ./borg/backup:/backup \
			nold360/borgserver:latest

Borgserver Configuration

• Place Borg-Clients SSH-PublicKeys in persistent storage
• Client Repositories will be named by the filename found in /sshkeys/clients/

Environment Variables

BORG_SERVE_ARGS

Use this variable if you want to set special options for the "borg serve"-command, which is used internally.

See the the documentation for all available arguments: borgbackup.readthedocs.io

Example

docker run -e BORG_SERVE_ARGS="--append-only --debug" (...) nold360/borgserver

Persistent Storages & Client Configuration

We will need two persistent storage directories for our borgserver to be usefull.

/sshkeys

This directory has two subdirectories:

/sshkeys/clients/

Here we will put all SSH public keys from our borg clients, we want to backup. Every key must be it's own file, containing only one line, with the key. The name of the file will become the name of the borg repository, we need for our client to connect.

That means every client get's it's own repository. So you might want to use the hostname of the client as the name of the sshkey file.

F.e. /sshkeys/clients/webserver.mydomain.com

Than your client would have to initiat the borg repository like this:

webserver.mydomain.com ~$ borg init ssh://borg@borgserver-container/backup/webserver.mydomain.com/my_first_repo

!IMPORTANT!: The container wouldn't start the SSH-Deamon until there is at least one ssh-keyfile in this directory!

/sshkeys/host/

This directory will be automaticly created on first start. Also run.sh will copy the SSH-Hostkeys here, so your clients can verify it's borgservers ssh-hostkey.

/backup

In this directory will borg write all the client data to. It's best to start with an empty directory.

Example Setup

docker-compose.yml

Here is a quick example, how to run borgserver using docker-compose:

services:
 borgserver:
  image: nold360/borgserver
  volumes:
   - /backup:/backup
   - ./sshkeys:/sshkeys
  ports:
   - "2222:22"
  environment:
   BORG_SERVE_ARGS: "--append-only"

~/.ssh/config

With this configuration (on your borg client) you can easily connect to your borgserver.

Host backup
	Hostname my.docker.host
	Port 2222
	User borg

Now initiate a borg-repository like this:

 $ borg init backup:my_first_borg_repo

And create your first backup!

 $ borg create backup:my_first_borg_repo::documents-2017-11-01 /home/user/MyImportentDocs