Secret generate fail with hostvars is undefined for kubernetes orchestration engine

My kolla-ansible and kolla-kubernetes code is upstream.
When I try to generate kubernetes secret, it raise following errors.

> tools/secret-generator.py create
File "tools/secret-generator.py", line 53, in <module>
    nsname = KollaKubernetesResources.GetJinjaDict()[nsname]
  File "/home/lyan/venvs/kolla-kubernetes/local/lib/python2.7/site-packages/kolla_kubernetes/service_resources.py", line 88, in GetJinjaDict
    r = JinjaUtils.dict_self_render(x)
  File "/home/lyan/venvs/kolla-kubernetes/local/lib/python2.7/site-packages/kolla_kubernetes/utils.py", line 181, in dict_self_render
    rendered_template = JinjaUtils.render_jinja(d, template)
  File "/home/lyan/venvs/kolla-kubernetes/local/lib/python2.7/site-packages/kolla_kubernetes/utils.py", line 166, in render_jinja
    rendered_template = j2env.get_template(name).render(dict_)
  File "/home/lyan/venvs/kolla-kubernetes/local/lib/python2.7/site-packages/jinja2/environment.py", line 989, in render
    return self.environment.handle_exception(exc_info, True)
  File "/home/lyan/venvs/kolla-kubernetes/local/lib/python2.7/site-packages/jinja2/environment.py", line 754, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "<template>", line 477, in top-level template code
  File "/home/lyan/venvs/kolla-kubernetes/local/lib/python2.7/site-packages/jinja2/environment.py", line 389, in getitem
    return obj[argument]
jinja2.exceptions.UndefinedError: 'hostvars' is undefined

kolla-kubernetes will found one file named ansible/group_vars/all.yml at kolla directory.
Then try to render the file.
There is one variable named tunnel_interface_addres at kolla-ansible upstream code.

tunnel_interface_address: "{{ hostvars[inventory_hostname]['ansible_' + tunnel_interface]['ipv4']['address'] }}"

This variable will not exist if we using kuberentes orchestration engine.
So there are two solution to fix this issue.

One is override the variable at globals.yml file or kolla-kuberenetes.yml file
The other is add condition statement which will determine whether orchestration engine is ansible at kolla-ansible's code.

I prefer we should add condition statement at kolla-ansible project.
Because of api_interface_address variable also have condition statement to determine whether orchestration engine is using ansible.