Use http request to check cinder api availability

Using a port open check is not reliable when going through a load
balancer.

httplib2 is added as it is required by the Ansible uri module.

Change-Id: I0e489e8f671b262c56c1442e7af85fd53c061598
Closes-bug: #1525208
Closes-Bug: #1510990

playbooks/roles/os_cinder/defaults/main.yml

@@ -232,6 +232,7 @@ cinder_requires_pip_packages:
   - virtualenv
   - virtualenv-tools
   - python-keystoneclient # Keystoneclient needed to OSA keystone lib
+  - httplib2
 
 # Common pip packages
 cinder_pip_packages:

playbooks/roles/os_cinder/tasks/cinder_backends.yml

@@ -13,11 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-- name: Ensure cinder api ip/port are responsive
-  wait_for:
-    port: "{{ cinder_service_port }}"
-    delay: 10
-    host: "{{ internal_lb_vip_address }}"
+- name: Ensure cinder api is available
+  uri:
+    url: "{{ cinder_service_internaluri }}"
+    status_code: 200
+  register: api_status
+  until: api_status |success
+  retries: 10
+  delay: 10
   tags:
     - cinder-backends