Add Cache-Control header for static files

staticFiles.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -28,5 +29,6 @@ func allStaticPaths() (paths []string) {
 
 // Gets only called by registered paths
 func serveStaticFile(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Cache-Control", fmt.Sprintf("public,max-age=%d,s-max-age=%d,stale-while-revalidate=%d", appConfig.Cache.Expiration, appConfig.Cache.Expiration/3, appConfig.Cache.Expiration))
 	http.ServeFile(w, r, filepath.Join(staticFolder, r.URL.Path))
 }