Most OpenStack API implementations, including fog, allow discovering the different endpoints (per components) from Keystone's catalog. Each component has public, internal and admin URLs. For most uses cases, using the public URL is the right choice (this is the default in fog) but some use cases may benefit from using internal URLs (when using a private OpenStack deployment, for exemple).

It would be great to add a URL type attribute per OpenStack compute resource, which would be publicURL by default, but could be set to internalURL.