Comment 4 for bug 1995778

Alex, thanks for the analysis! I came to the same conclusion regaring api-paste.ini but you were much quicker to post the results of your investigation. Good stuff!

I tested it and added the following to the templates/mitaka/api-paste.ini template on nova-cloud-controler unit.
```
api_version = {{ api_version }}
```

The resulting /etc/nova/api-paste.ini ended up with the correct configuration rendered:

```
$ sudo grep api_version /etc/nova/api-paste.ini
api_version = 3
```

Then, after I executed the config-changed hook on nova-ironic unit, the configuration in nova.conf has been correctly rendered with /v3:

```
$ sudo grep -A2 '\[ironic\]' /etc/nova/nova.conf
[ironic]
auth_type = password
auth_url = https://keystone-internal.engineering-cloud.example.com:35357/v3
```