vmdesc2xml: Command to print libvirt domain XML

The `vmdesc2xml` command reads a VM description from a YAML document and
prints the generated libvirt domain XML to stdout. This can be useful
for debugging or other purposes besides creating VMs directly.

setup.py

@@ -13,6 +13,7 @@ setup(
     entry_points={
         'console_scripts': [
             'mkvm=mkvm.mkvm:main',
+            'vmdesc2xml=mkvm.vmdesc:main',
         ],
     },
 )

src/mkvm/vmdesc.py

@@ -1,7 +1,9 @@
 from . import storage
+import argparse
 import logging
 import os
 import re
+import sys
 import tempfile
 import yaml
 try:
@@ -400,3 +402,13 @@ class VirtualMachine(object):
         storage.create_lvm_vg(self.vg_name, *pvs)
         for vol in self.volumes:
             storage.create_lvm_lv(self.vg_name, vol['name'], vol['size'])
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('description',
+                        help='Path to VM description document')
+    args = parser.parse_args()
+
+    vm = VirtualMachine.from_yaml(args.description)
+    sys.stdout.write(vm.to_xml(True))