borg_add_client.sh

#!/bin/bash
####################################################
# borg_add_client.sh - Version: 0.1
# By Gerrit 'Nold' Pannek - 03/2016
# GPLv3 Licensed - https://gnu.org/licenses/gpl.txt
#
# This script helps to add a new ssh client on
# a borg backup server.
#
# Configuration:
#  Change BORG_DIR & BORG_USER variables in this
#  script:
#  - BORG_DIR is the base-directory where all
#    borg-repostories are located.
#  - BORG_USER is the local user which all borg
#    clients use via ssh
#
# Executing:
#  When executing this script, you need to pass two
#  parameters to it:
#  - HOSTNAME: Hostname of the client & will become
#    the repository name
#  - SSH_KEY: SSH-Public-Key of the borg client
#
# Example:
#  # borg_add_client.sh myclient.lan "ssh-rsa AAAAB3NzaC1yc2E... nold@myclient.lan"
####################################################

function usage {
    echo "Add Client to Borg-Backup"
    echo "Usage: $0 <HOSTNAME> <SSH-KEY>"
    echo
    echo $1
    exit 1
}

### CONFIG:
BORG_DIR=/backup
BORG_USER=borg
### END CONFIG

# Params
HOSTNAME=$1
SSH_KEY=$2

# Check if everything is setup correctly
[ ! -d "${BORG_DIR}" -o -z "${BORG_USER}" ] && usage "ERROR: You must configure BORG_DIR and BORG_USER correctly."
[ -z "${HOSTNAME}" -o -z "${SSH_KEY}" ] && usage

USER_HOME=$(awk -F: "/^${BORG_USER}:/ {print \$6}" /etc/passwd)
[ ! -d "${USER_HOME}" ] && usage "ERROR: User ${BORG_USER} home doesn't exist: ${USER_HOME}"
[ ! -e "${USER_HOME}/.ssh/authorized_keys" ] && usage "ERROR: User ${BORG_USER} authorized_keys doesn't exist: ${USER_HOME}/.ssh/authorized_keys"

# Check if TARGET_DIR exists, otherwise create it
TARGET_DIR="${BORG_DIR}/${HOSTNAME}"
[ ! -e "$TARGET_DIR" ] && mkdir -p "$TARGET_DIR" 2>/dev/null && chown -R ${BORG_USER}: "$TARGET_DIR"

# Check if SSH_KEY is already in use
# grep -q "${SSH_KEY}" ${USER_HOME}/.ssh/authorized_keys && usage "ERROR: Key already in use!"

# Check if TARGET_DIR is already in use
# grep -q "${TARGET_DIR}" ${USER_HOME}/.ssh/authorized_keys && usage "ERROR: TARGET_DIR \"${TARGET_DIR}\" already in use!"

# Add Key and Params to authorized_keys
echo "command=\"cd ${TARGET_DIR}; borg serve --restrict-to-path ${TARGET_DIR}\",no-port-forwarding,no-X11-forwarding,no-pty,no-agent-forwarding,no-user-rc ${SSH_KEY}" >> ${USER_HOME}/.ssh/authorized_keys

echo "Borg repository \"${TARGET_DIR}\" successfully created & SSH-Key Authorized"
exit 0