go ServeFile

package main

import (
 "fmt"
 "net/http"
)

func main() {

 http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
  w.Header().Add("Content-Disposition", fmt.Sprintf("attachment; filename=%s", "sublime_text.tar.bz2"))
  w.Header().Add("Content-Type", "application/octet-stream")
  http.ServeFile(w, r, "/home/steven/sublime_text.tar.bz2")
 })

 err := http.ListenAndServe(":8090", nil)
 if err != nil {
  fmt.Println(err)
 }
}