#!/bin/bash

#
# Libvirt VMs backup script 
# Upload gziped images of VMs volumes to remote server using SSH
# Public key authentication is required
# Images stored on daily and weekly (each sunday) basis
#
# Written by Andrii Salnikov aka manf@grid.org.ua
#

# configuration
SE_SSH="cluster.univ@se.imbg.org.ua"
SE_PATH="/mnt/se1/backups/cluster.univ.kiev.ua/vm-images/"
EXCLUDE_LIST=( '^h7091.*' )

#TODO: handle turned off VMs

# functions
get_all_vms () {
	VMS=( $(virsh list --all | sed '$d' | sed -n '3,$p' | awk '{print $2}') )
}

check_vm_excluded () {
	local vm=$1
	for exclude in "${EXCLUDE_LIST[@]}"; do
		echo $vm | grep -q -e "$exclude"
		[ $? -eq 0 ] && return 1
	done
	return 0
}

get_vm_disks () {
	local vm=$1
	virsh domblklist $vm | sed -n 's/[vsh]d[a-z]\s\+\(\/.*\)/\1/p'
}

check_lvm () {
	local path=$1
	lvs $path > /dev/null 2>&1
	return $?
}

get_lvm_snapshot () {
	local path=$1
	local devname=${path##*/}
	lvcreate -s -L 1G -n "${devname}-snapshot" $path > /dev/null
	if [ $? -ne 0 -a $? -ne 5 ]; then 
		echo "ERROR: Failed to create LVM snapshot for: $path"
		return 1
	fi
	echo "${path%/*}/${devname}-snapshot"
	return 0
}

remove_lvm_snapshot () {
	local path=$1
	sync
	lvremove -f $path
}

get_backup_file () {
	local day_of_week=$( date +"%w" )  # 0-6
	local day_of_month=$( date +"%_d" ) # 1-...
	local week_of_month=$(( ($day_of_month-1)/7 ))
	[ $week_of_month -eq 4 ] && week_of_month=3
	if [ $day_of_week -eq 0 ]; then 
		echo "weekly/w${week_of_month}-"
	else
		echo "daily/d${day_of_week}-"
	fi
}

make_remotedirs () {
	 ssh $SE_SSH " mkdir -p $SE_PATH/{daily,weekly}"
}

do_backup () {
	local disk=$1
	local filename=${disk##*/}
	filename=${filename%-snapshot}
	local filepath="$( get_backup_file )${filename}.img.gz"

	make_remotedirs
	echo "INFO: Backing up $disk to $filepath"
	dd if=$disk | gzip | ssh $SE_SSH " cat > $SE_PATH/$filepath"
}

do_xml_backup () {
	local vmname=$1
	local filepath="$( get_backup_file )${vmname}-config.xml.gz"
	virsh dumpxml $vmname | gzip | ssh $SE_SSH " cat > $SE_PATH/$filepath"
}

# main cycle
get_all_vms
for vm in "${VMS[@]}"; do
	echo "INFO: Processing VM $vm"
	check_vm_excluded $vm
	if [ $? -ne 0 ]; then 
		echo "NOTICE: VM $vm has excluded in the configuration"
		continue
	fi
        do_xml_backup $vm
	vmdisks=$( get_vm_disks $vm )
	for disk in $vmdisks; do
		echo "INFO: Found disk $disk for VM $vm"
		check_lvm $disk
		if [ $? -ne 0 ]; then
			echo "ERROR: VM $vm disk $disk is not LVM volume. Non-LVM volumes is not supported yet."
			continue 2
		else
			echo "INFO: Creating LVM snapshot for disk $disk"
			disk_snap=$( get_lvm_snapshot $disk )
			[ $? -ne 0 ] && continue
			do_backup $disk_snap
			remove_lvm_snapshot $disk_snap
		fi
	done
done