#!/bin/sh
# vim: set sw=4 ts=4 sts=4 et :

cordon() {
    printf 'Cordoning node %s ... ' "$1" >&2
    if kubectl cordon "$1"; then
        :
    else
        r=$?
        echo FAILED >&2
        return $r
    fi
}

drain() {
    printf 'Draining node %s ... ' "$1"
    kubectl drain \
        --ignore-daemonsets \
        --pod-selector 'app!=csi-attacher,app!=csi-provisioner' \
        --delete-emptydir-data \
        "$1"
}

migrate() {
    printf 'Migrating %s to %s ... \n' "$1" "$2" >&2
    virsh migrate "$1" "$2" --live --persistent --undefinesource --verbose
}

shutdown() {
    if [ "$(virsh domstate "$1")" = 'shut off' ]; then
        printf 'VM %s is already shut off\n' "$1" >&2
        return 0
    fi
    virsh shutdown "$1" || return
    printf 'Waiting for %s to shut down ... ' "$1" >&2
    if virsh event --event lifecycle "$1"; then
        echo OK >&2
    else
        r=$?
        echo FAILED >&2
        return $r
    fi
}

host="$1"
export LIBVIRT_DEFAULT_URI=qemu+ssh://${host}/system

case "${host}" in
vmhost0.pyrocufflink.blue)
    dest=qemu+ssh://vmhost1.pyrocufflink.blue/system
    ;;
vmhost1.pyrocufflink.blue)
    dest=qemu+ssh://vmhost0.pyrocufflink.blue/system
    ;;
*)
    printf 'Unknown VM host: %s\n' "${host}" >&2
    exit 1
    ;;
esac

printf 'Checking libvirt connection ... '
virsh uri || exit

set --
nodes=$(
    kubectl get node -o name -l '!node-role.kubernetes.io/control-plane' \
    | sed s@node/@@
)
for node in ${nodes}; do
    if virsh domuuid "${node%%.*}" >/dev/null 2>&1; then
        set -- "$@" "${node}"
        cordon "${node}" || exit
    fi
done

for node; do
    drain "${node}" || exit
done

for node; do
    shutdown "${node%%.*}" || exit
done

virsh list --name | while read -r vm_name; do
    [ -n "${vm_name}" ] || continue
    if [ "$(virsh domstate "${vm_name}")" = running ]; then
        migrate "${vm_name}" "${dest}" || exit
    fi
done