Fix libvirt metadata used to store ansible tags

According to https://libvirt.org/formatdomain.html#elementsMetadata , the `metadata` tag can contain only one top-level element per namespace.
Because of that, libvirt stored only the `deployment-type-{{ deployment_type }}` tag.
As a consequence, the dynamic inventory reported no `env-{{ cluster }}` group.
This is problematic for the `terminate.yml` playbook which iterates over `groups['tag-env-{{ cluster-id }}]`
The symptom is that `oo_hosts_to_terminate` was not defined.
In the end, as Ansible couldn’t iterate on the value of `groups['oo_hosts_to_terminate']`, it iterated on its letters:
```
TASK: [Destroy VMs] ***********************************************************
failed: [localhost] => (item=['g', 'destroy']) => {"failed": true, "item": ["g", "destroy"]}
msg: virtual machine g not found
failed: [localhost] => (item=['g', 'undefine']) => {"failed": true, "item": ["g", "undefine"]}
msg: virtual machine g not found
failed: [localhost] => (item=['r', 'destroy']) => {"failed": true, "item": ["r", "destroy"]}
msg: virtual machine r not found
failed: [localhost] => (item=['r', 'undefine']) => {"failed": true, "item": ["r", "undefine"]}
msg: virtual machine r not found
failed: [localhost] => (item=['o', 'destroy']) => {"failed": true, "item": ["o", "destroy"]}
msg: virtual machine o not found
failed: [localhost] => (item=['o', 'undefine']) => {"failed": true, "item": ["o", "undefine"]}
msg: virtual machine o not found
failed: [localhost] => (item=['u', 'destroy']) => {"failed": true, "item": ["u", "destroy"]}
msg: virtual machine u not found
failed: [localhost] => (item=['u', 'undefine']) => {"failed": true, "item": ["u", "undefine"]}
msg: virtual machine u not found
failed: [localhost] => (item=['p', 'destroy']) => {"failed": true, "item": ["p", "destroy"]}
msg: virtual machine p not found
failed: [localhost] => (item=['p', 'undefine']) => {"failed": true, "item": ["p", "undefine"]}
msg: virtual machine p not found
failed: [localhost] => (item=['s', 'destroy']) => {"failed": true, "item": ["s", "destroy"]}
msg: virtual machine s not found
failed: [localhost] => (item=['s', 'undefine']) => {"failed": true, "item": ["s", "undefine"]}
msg: virtual machine s not found
failed: [localhost] => (item=['[', 'destroy']) => {"failed": true, "item": ["[", "destroy"]}
msg: virtual machine [ not found
failed: [localhost] => (item=['[', 'undefine']) => {"failed": true, "item": ["[", "undefine"]}
msg: virtual machine [ not found
failed: [localhost] => (item=["'", 'destroy']) => {"failed": true, "item": ["'", "destroy"]}
msg: virtual machine ' not found
failed: [localhost] => (item=["'", 'undefine']) => {"failed": true, "item": ["'", "undefine"]}
msg: virtual machine ' not found
failed: [localhost] => (item=['o', 'destroy']) => {"failed": true, "item": ["o", "destroy"]}
msg: virtual machine o not found
failed: [localhost] => (item=['o', 'undefine']) => {"failed": true, "item": ["o", "undefine"]}
msg: virtual machine o not found
etc…
```

inventory/libvirt/hosts/libvirt_generic.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2
 
 """
 libvirt external inventory script
@@ -131,7 +131,7 @@ class LibvirtInventory(object):
 
             root = ET.fromstring(domain.XMLDesc())
             ns = {'ansible': 'https://github.com/ansible/ansible'}
-            for tag_elem in root.findall('./metadata/ansible:tag', ns):
+            for tag_elem in root.findall('./metadata/ansible:tags/ansible:tag', ns):
                 tag = tag_elem.text
                 self.push(inventory, "tag_%s" % tag, domain_name)
                 self.push(hostvars, 'libvirt_tags', tag)

playbooks/libvirt/openshift-cluster/templates/domain.xml

@@ -2,10 +2,12 @@
   <name>{{ item }}</name>
   <memory unit='GiB'>1</memory>
   <metadata xmlns:ansible="https://github.com/ansible/ansible">
-    <ansible:tag>deployment-type-{{ deployment_type }}</ansible:tag>
-    <ansible:tag>env-{{ cluster }}</ansible:tag>
-    <ansible:tag>env-host-type-{{ cluster }}-openshift-{{ type }}</ansible:tag>
-    <ansible:tag>host-type-{{ type }}</ansible:tag>
+    <ansible:tags>
+      <ansible:tag>deployment-type-{{ deployment_type }}</ansible:tag>
+      <ansible:tag>env-{{ cluster }}</ansible:tag>
+      <ansible:tag>env-host-type-{{ cluster }}-openshift-{{ type }}</ansible:tag>
+      <ansible:tag>host-type-{{ type }}</ansible:tag>
+    </ansible:tags>
   </metadata>
   <currentMemory unit='GiB'>1</currentMemory>
   <vcpu placement='static'>2</vcpu>