feat(layer,queue): prevent browser caching for queue page

internal/proxy/director/layer/queue/queue.go

@@ -7,6 +7,7 @@ import (
 	"math/rand"
 	"net/http"
 	"path/filepath"
+	"strconv"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -181,6 +182,8 @@ func (q *Queue) renderQueuePage(w http.ResponseWriter, r *http.Request, queueNam
 		RefreshRate:     refreshRate,
 	}
 
+	w.Header().Add("Cache-Control", "no-cache")
+	w.Header().Add("Retry-After", strconv.FormatInt(int64(refreshRate.Seconds()), 10))
 	w.WriteHeader(http.StatusServiceUnavailable)
 
 	if err := q.tmpl.ExecuteTemplate(w, "queue", templateData); err != nil {