Site-wide configuration

[sleiner]

Discussed in #1199

^{Originally posted by sleiner July 5, 2022}
In PDM 2.0, there are two "layers" of configuration as far as I see (ranked by descending priority):

• Project Configuration (which is, of course, project-specific)
• Home Configuration (which is user specific)

I'm proposing to add a third layer, located at platformdirs.site_config_dir("pdm") which serves as the lowest-priority layer.
This layer should be read-only in the CLI.

Why would this be helpful?

For multi-user setups, it would make sense for the system administrator to set some default settings, e.g. the default Python path or a potential PyPI mirror.