pull-through dist server

cmd/dkl-local-server/upstream.go

@@ -9,9 +9,11 @@ import (
 	"log"
 	"net/http"
 	"os"
+	"path"
 	gopath "path"
 	"path/filepath"
 	"strconv"
+	"strings"
 	"time"
 
 	"github.com/dustin/go-humanize"
@@ -22,8 +24,22 @@ var (
 	upstreamURL = flag.String("upstream", "https://dkl.novit.io/dist", "Upstream server for dist elements")
 )
 
-func (ctx *renderContext) distFetch(path ...string) (outPath string, err error) {
-	outPath = ctx.distFilePath(path...)
+type upstreamServer struct{}
+
+func (_ upstreamServer) ServeHTTP(w http.ResponseWriter, req *http.Request) {
+	path := path.Clean(req.URL.Path)
+	outPath, err := distFetch(strings.Split(path, "/")...)
+	if err != nil {
+		w.WriteHeader(http.StatusBadGateway)
+		w.Write([]byte(err.Error() + "\n"))
+		return
+	}
+
+	http.ServeFile(w, req, outPath)
+}
+
+func distFetch(path ...string) (outPath string, err error) {
+	outPath = distFilePath(path...)
 
 	if _, err = os.Stat(outPath); err == nil {
 		return