Add initial support for creating volumes

For some services it may be desirable to have instances using
cinder volumes, this change allows to define that in the
infra_config.yml inventory and the provision_infra_servers
will create them.
A follow-up patch will attach the volumes defined on each instance.

Change-Id: I28d187569655fbbc45cec0bce771ce8adab1f4dd

infra_config.yml.sample

@@ -28,6 +28,11 @@ infra_servers:
     net_name: your_neutron_network
     security_groups: "default,webserver"
     infra_type: gerrit
+    volumes:
+      - name: gerrit_volume
+        size: 40
+      - name: gerrit_volume2
+        size: 60
   - name: nodepool
     image: 9d25fe2d-cf31-4b05-8c58-f238ec78e633
     flavor: standard.small

roles/provision_infra_servers/tasks/main.yml

@@ -16,3 +16,13 @@
       group: infra
       infra_type: "{{ item.infra_type }}"
   with_items: infra_servers
+
+- name: Create OpenStack volumes
+  os_volume:
+    state: present
+    cloud: "{{item.os_client_config_cloud | default(os_client_config_cloud) }}"
+    display_name: "{{ item.1.name }}"
+    size: "{{ item.1.size }}"
+  with_subelements:
+    - infra_servers
+    - volumes