scripts: Add VM host maintenance scripts

The `migrate-all.sh` script is used to migrate one or more VMs (default:
all) from one VM host to the other on demand.

The `shutdown-vmhost.sh` script prepares a VM host to shut down by
evicting Kubernetes Pods from the Nodes running on that host and then
shutting them down, followed by migrating the rest of the running VMs to
the other host.

scripts/migrate-all.sh

@@ -0,0 +1,28 @@
+#!/bin/sh
+# vim: set sw=4 ts=4 sts=4 et :
+
+list_vms() {
+    if [ $# -gt 0 ]; then
+        echo "$@" | xargs -n1
+    else
+        virsh list --name
+    fi
+}
+
+src=$1
+shift 2>&-
+dest=$1
+shift 2>&-
+
+if [ -z "${src}" ] || [ -z "${dest}" ]; then
+    printf 'usage: %s source_uri dest_uri [name [...]]\n' "${0##*/}"
+    exit 2
+fi
+
+export LIBVIRT_DEFAULT_URI="${src}"
+
+list_vms "$@" | while read name; do
+    [ -n "${name}" ] || continue
+    printf 'Migrating %s ...\n' "${name}"
+    virsh migrate "${name}" "${dest}" --live --persistent --undefinesource --verbose
+done