Make wordpress role pass container argument spec validation when docker_service_suffix is defined

roles/wordpress/tasks/main.yml

@@ -4,6 +4,11 @@
   set_fact:
     dockerfile: {}
 
+- name: Set docker service full name (required because docker_env uses it)
+  set_fact:
+    docker_service_name: "wordpress_{{ docker_service_suffix }}"
+  when: docker_service_suffix is defined
+
 - name: Add memcached php extension to container
   set_fact:
     dockerfile: "{{ dockerfile | combine({'run': \