Improvements required for config merging

[Paul Bourke]

Naming
======
The naming scheme used for config merging in some of the services needs to be improved / made more consistent. We're coming across confusion from operators such as the following (paraphrased)

"I've added an ini file in /etc/kolla/config/cinder-api/cinder.conf on the system running kolla-ansible, and none of the parameters are showing up on my target system."

Answer here is to put it in either /etc/kolla/config/cinder.conf or /etc/kolla/config/cinder/cinder-api.conf. This is confusing, either both situations should be supported or documentation needs to be better.

Flexibility
===========
"I want to make changes to nova.conf on *api nodes only*. I put changes in /etc/kolla/config/nova/nova-api.conf but they're ending up on compute nodes"

There's currently no way of doing the above.

[Jeffrey Zhang (jeffrey4l)]

should only support one situation. The choice is bad.

> "I want to make changes to nova.conf on *api nodes only*. I put changes in /etc/kolla/config/nova/nova-api.conf but they're ending up on compute nodes"

the configure should be only copied to the node who need it, this is a bug[0].

the custom config file also support ansible template and this should be documented. like

cat <<EOF > /etc/kolla/config/nova.conf
{% if service_name='nova-api' %}
[DEFAULT]
debug=True
{% endif %}

[0] https://bugs.launchpad.net/kolla/+bug/1559122

[Radosław Piliszek (yoctozepto)]

Mark's idea: add documentation that you can mix host/group vars and config overrides as they are templatable.