@algernon All that's really needed for a binary cache is to have the files exposed through some kind of webserver. Hydra can shift these files to the correct place for eg. an nginx to find them, though the setup was not very well-documented last I did this...

I have a few random notes here but they don't seem to go into the 'cache' part: https://wiki.slightly.tech/books/miscellaneous-notes/page/setting-up-hydra