This part is well documented in the SOC7 docs:
[CODE]13.1 Default Configuration Files
By default, a configuration snippet with a basic configuration for each OpenStack component is available in the following directory:
/etc/SERVICE/SERVICE.conf.d/010-SERVICE.conf
For example: /etc/nova/nova.conf.d/010-nova.conf
Those files should not be modified.
13.2 Custom Configuration Files
To adjust or overwrite settings for the respective OpenStack component, add a custom configuration file to the same directory, /etc/SERVICE/SERVICE.conf.d/.
The same applies if you want to configure individual components or roles of an OpenStack component, like nova-api or nova-compute, for example. But in this case, add your custom configuration file to the following directory:
/etc/SERVICE/ROLE.conf.d/
All custom configuration file must follow the rules listed in Section 13.3, ÂNaming Conventions for Custom Configuration FilesÂ.
13.3 Naming Conventions for Custom Configuration Files
Use the following rules for any configuration files you add:
- The file name must start with a 3-digit number and a dash. For example: /etc/nova/nova.conf.d/500-nova.conf
- The file must have the following file name extension: .conf
- For configuration management systems (for example: Crowbar, Salt), use numbers between 100 and 499.
- To override settings written by the configuration management system, use numbers starting from 500. They have higher priority.
13.4 Processing Order of Configuration Files
The configuration files are processed in the following order:
/etc/SERVICE/SERVICE.conf
/etc/SERVICE/SERVICE.conf.d/*.conf (in dictionary order)
/etc/SERVICE/ROLE.conf.d/*.conf (in dictionary order)
If conflicting values are set for the same parameter, the last configured value overwrites all previous ones. In particular, values defined in
/etc/SERVICE/SERVICE.conf.d/XXX-SERVICE.conf
overwrite configuration values in
/etc/SERVICE/SERVICE.conf[/CODE]