Mine is like this:
[main]
fastestmirror=True
gpgcheck=1
max_parallel_downloads=10
installonly_limit=2
clean_requirements_on_remove=True
keepcache=True
ip_resolve=4
You also have to take in consideration that you might playing with to different cache’s. On the workstation it self at least. I don’t know how it looks like with docker … do you always use sudo to use dnf?
I had the problem that when i just wanted to get an info of a package that i used dnf without sudo. This creates a cache for my own user … if you do with sudo it creates a other cache for the root privileged user. I always was creating cache while waiting to execute the command it self.
See here:
https://discussion.fedoraproject.org/t/can-make-dnf-cache-system-wide-instead-of-per-user/73981