Merge "Add compute inventory precheck"

ansible/roles/nova/tasks/precheck.yml

@@ -11,6 +11,11 @@
       - placement_api
   register: container_facts
 
+- name: Checking available compute nodes in inventory
+  fail:
+    msg: "At least 1 compute node required in inventory"
+  when: groups['compute'] | length < 1
+
 - name: Checking free port for Nova API
   vars:
     nova_api: "{{ nova_services['nova-api'] }}"