Package cachefs implements a read-only cache around a fs.FS, using groupcache. Using cachefs is straightforward: cachefs "wraps" the underlying file system with caching. You can specify groupcache parameters - the group name and the cache size. groupcache does not support expiration, but cachefs supports quantizing values so that expiration happens around the expiration duration provided. Expiration can be disabled by specifying 0 for the duration. See https://pkg.go.dev/github.com/golang/groupcache for more information on groupcache.