#!/usr/bin/env bash

# migrate_vm - Exports a VM from a PVC cluster to another PVC cluster
# Part of the Parallel Virtual Cluster (PVC) system
#
#    Copyright (C) 2018-2020 Joshua M. Boniface <joshua@boniface.me>
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, version 3.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <https://www.gnu.org/licenses/>.
#
###############################################################################

set -o errexit
set -o pipefail

usage() {
    echo -e "Export a VM from a PVC cluster to another PVC cluster."
    echo -e "Usage:"
    echo -e "  $0 <vm> <source_cluster> <destination_cluster> <destination_pool>"
    echo -e ""
    echo -e "Important information:"
    echo -e " * The local user must have valid SSH access to the primary coordinator in the source_cluster."
    echo -e " * The user on the cluster primary coordinator must have 'sudo' access."
    echo -e " * If the VM is not in 'stop' state, it will be shut down."
    echo -e " * Do not switch the cluster primary coordinator on either cluster while the script is running."
    echo -e " * Ensure you have enough space on the target cluster to store all VM disks."
}

fail() {
    echo -e "$@"
    exit 1
}

# Arguments
if [[ -z ${1} || -z ${2} || -z ${3} || -z ${4} ]]; then
    usage
    exit 1
fi
source_vm="${1}"
source_cluster="${2}"
destination_cluster="${3}"
destination_pool="${4}"

# Verify each cluster is reachable
pvc -c ${source_cluster} status &>/dev/null || fail "Specified source_cluster is not accessible"
pvc -c ${destination_cluster} status &>/dev/null || fail "Specified destination_cluster is not accessible"

# Determine the connection IPs
source_cluster_address="$( pvc cluster list 2>/dev/null | grep -i "^${source_cluster}" | awk '{ print $2 }' )"
destination_cluster_address="$( pvc cluster list 2>/dev/null | grep -i "^${destination_cluster}" | awk '{ print $2 }' )"

# Attempt to connect to the cluster addresses
ssh ${source_cluster_address} which pvc &>/dev/null || fail "Could not SSH to source_cluster primary coordinator host"
ssh ${destination_cluster_address} which pvc &>/dev/null || fail "Could not SSH to destination_cluster primary coordinator host"

# Verify that the VM exists
pvc -c ${source_cluster} vm info ${source_vm} &>/dev/null || fail "Specified VM is not present on the source cluster"

echo "Verification complete."

# Shut down the VM
echo -n "Shutting down VM..."
set +o errexit
pvc -c ${source_cluster} vm shutdown ${source_vm} &>/dev/null
shutdown_success=$?
while ! pvc -c ${source_cluster} vm info ${source_vm} 2>/dev/null | grep '^State' | grep -q -E 'stop|disable'; do
    sleep 1
    echo -n "."
done
set -o errexit
echo " done."

tempfile="$( mktemp )"

# Dump the XML file
echo -n "Exporting VM configuration file from source cluster... "
pvc -c ${source_cluster} vm dump ${source_vm} 1> ${tempfile} 2>/dev/null
echo "done."

# Import the XML file
echo -n "Importing VM configuration file to destination cluster... "
pvc -c ${destination_cluster} vm define ${tempfile}
echo "done."

rm -f ${tempfile}

# Determine the list of volumes in this VM
volume_list="$( pvc -c ${source_cluster} vm info --long ${source_vm} 2>/dev/null | grep -w 'rbd' | awk '{ print $3 }' )"

# Parse and migrate each volume
for volume in ${volume_list}; do
    volume_pool="$( awk -F '/' '{ print $1 }' <<<"${volume}" )"
    volume_name="$( awk -F '/' '{ print $2 }' <<<"${volume}" )"
    volume_size="$( pvc -c ${source_cluster} storage volume list -p ${volume_pool} ${volume_name} 2>/dev/null | grep "^${volume_name}" | awk '{ print $3 }' )"
    echo "Transferring disk ${volume_name} (${volume_size})... "
    pvc -c ${destination_cluster} storage volume add ${destination_pool} ${volume_name} ${volume_size} 2>/dev/null
    ssh ${source_cluster_address} sudo rbd map ${volume_pool}/${volume_name} &>/dev/null || fail "Failed to map volume ${volume} on source cluster"
    ssh ${destination_cluster_address} sudo rbd map ${volume_pool}/${volume_name} &>/dev/null || fail "Failed to map volume ${volume} on destination cluster"
    ssh ${source_cluster_address} sudo dd if="/dev/rbd/${volume_pool}/${volume_name}" bs=1M 2>/dev/null | pv | ssh ${destination_cluster_address} sudo dd bs=1M of="/dev/rbd/${destination_pool}/${volume_name}" 2>/dev/null
    ssh ${source_cluster_address} sudo rbd unmap ${volume_pool}/${volume_name} &>/dev/null || fail "Failed to unmap volume ${volume} on source cluster"
    ssh ${destination_cluster_address} sudo rbd unmap ${volume_pool}/${volume_name} &>/dev/null || fail "Failed to unmap volume ${volume} on destination cluster"
done

if [[ ${shutdown_success} -eq 0 ]]; then
    pvc -c ${destination_cluster} vm start ${source_vm}
fi