Actually I'm having exactly the same symptom/issue as question 46403678: The links returned are invalid. The solution posted there appears to require the use of the Gorilla mux:
r.PathPrefix("/download/").Handler(
http.StripPrefix("/download", http.FileServer(http.Dir(dirPath))),
).Methods("GET")
I'm looking for a solution that doesn't require importing any 3rd party packages.