Add libvirt_vm_config.py filter plugins

These filter plugins allow mapping from declarative Tenks VM definitions
to config that can be accepted by the stackhpc.libvirt-vm role.

ansible/filter_plugins/libvirt_vm_config.py

@@ -0,0 +1,61 @@
+from ansible.errors import AnsibleFilterError
+from ansible.module_utils._text import to_text
+from jinja2 import contextfilter
+
+
+class FilterModule(object):
+    '''Libvirt configuration filters'''
+
+    def filters(self):
+        return {
+            'set_libvirt_interfaces': set_libvirt_interfaces,
+            'set_libvirt_volume_pool': set_libvirt_volume_pool,
+        }
+
+
+# Lifted from kayobe:ansible/filter_plugins/networks.py
+def _get_hostvar(context, var_name, inventory_hostname=None):
+    if inventory_hostname is None:
+        namespace = context
+    else:
+        if inventory_hostname not in context['hostvars']:
+            raise errors.AnsibleFilterError(
+                "Inventory hostname '%s' not in hostvars" % inventory_hostname)
+        namespace = context["hostvars"][inventory_hostname]
+    return namespace.get(var_name)
+
+
+@contextfilter
+def set_libvirt_interfaces(context, vm):
+    """Set interfaces for a VM's specified physical networks.
+    """
+    physnet_mappings = _get_hostvar(context, 'physnet_mappings')
+    veth_prefix = _get_hostvar(context, 'veth_prefix')
+    veth_    = _get_hostvar(context, 'veth_base_name')
+
+
+    vm['interfaces'] = []
+    physnets = vm.pop('physical_networks', [])
+    for physnet in physnets:
+        try:
+            vm['interfaces'].append(
+                {'type': 'direct',
+                 'source': {'dev': physnet_mappings[physnet]}}
+            )
+        except KeyError:
+            raise AnsibleFilterError(to_text(
+                "No interface mapping was specified for physical network "
+                "'%s'." % physnet
+            ))
+     return vm
+
+
+def set_libvirt_volume_pool(vm, volume_pool):
+    """
+    Set the Libvirt volume pool for each volume.
+
+    :param vm: A VM definiton.
+    :param volume_pool: The name of the Libvirt volume pool to use.
+    """
+    for vol in vm.get('volumes', []):
+        vol['pool'] = volume_pool