bpcadd

#!/bin/bash
#
# Enrolling a new host into BackupPC.
# Also provides helpers to print out BackupPC's SSH public key with recommended
# authorized_keys options and remove hosts.

set -euo pipefail

# Print usage information for this tool.
show_usage() {
	cat <<EOF
Usage: $0 [OPTION]
   or: $0 HOSTNAME
   or: $0 -R HOSTNAME
Adds or removes the client HOSTNAME to BackupPC.

   -h, --help       show usage
   -k, --ssh-key    print ssh public key in a format for authorized_keys
   -R, --remove     remove the client from BackupPC

Client requirements:
 - BackupPC SSH public added to root authorized_keys, viewable with the
   --ssh-key argument to this script.
 - SSH command is set to /usr/bin/rsync with the 'command' option in
   authorized_keys.
 - Must have rsync installed.

Author: Ollie Armstrong <ollie@fubra.com> 2016
EOF
}

# Echos everything passed to it to stderr.
err() {
	cat <<< "$@" 1>&2;
}

# Print BackupPC's SSH public key proceeded by a comment and authorized_keys
# options.
ssh_key() {
	public_key=$(</var/lib/BackupPC/.ssh/id_rsa.pub)
	ip_addresses=$(ip addr | grep inet | awk '{print $2}' | grep -v '127.0.0.1/8' | cut -d'/' -f1 | tr '\n' ',' | sed 's/,$//')
	ssh_key_preamble="# BackupPC\ncommand=\"/usr/bin/rsync \$SSH_ORIGINAL_COMMAND\",from=\"$ip_addresses\",no-agent-forwarding,no-port-forwarding,no-x11-forwarding"

	echo -e "$ssh_key_preamble $public_key"
}

# Checks if the client is already enrolled in BackupPC.
client_exists() {
	if grep -Pq "^$1 " /etc/BackupPC/hosts; then
		return 0
	fi

	return 1
}

# Add the client into BackupPC.
add_client() {
	client_hostname=$1

	# Accept the client's ssh host key
	sudo -u backuppc ssh -q -o StrictHostKeyChecking=no "root@$client_hostname" -- --help >/dev/null

	# Add client to BackupPC hosts file
	echo "$client_hostname 0 root" >>/etc/BackupPC/hosts
}

# Removes a client from BackupPC.
remove_client() {
	client_hostname=$1

	sed -i "/^$client_hostname\s/d" /etc/BackupPC/hosts
	sed -i "/^$client_hostname,/d" /var/lib/BackupPC/.ssh/known_hosts

	# Remove client backups
	if [ -d "/var/lib/BackupPC/pc/$client_hostname" ]; then
		rm -rf "/var/lib/BackupPC/pc/$client_hostname"
	fi

	# Remove client specific config
	if [ -f "/etc/BackupPC/pc/${client_hostname}.pl" ]; then
		rm "/etc/BackupPC/pc/${client_hostname}.pl"
	fi
	
	echo "Removed ${client_hostname}, it'll remain in BackupPC until the next wakeup."
	echo "Now remove the SSH key from the client."
}

if [ "$#" -eq 0 ]; then
	show_usage
	exit 1
fi

while :; do
	case $1 in
		-h|--help)
			show_usage
			exit
			;;
		-k|--ssh-key)
			ssh_key
			exit
			;;
		-R|--remove)
			shift
			remove_client $1
			exit
			;;
		*)
			break
	esac

	shift
done

if client_exists $1; then
	err "Host already exists" 
	exit 2
fi

add_client $1
echo "System added, it will be backed up automatically on the next hour."