update the delivery of the index.html page so that we can inject values into it dynamically.

src/metabase/routes.clj

@@ -2,8 +2,28 @@
   (:require [compojure.core :refer [context defroutes GET]]
             [compojure.route :as route]
             [ring.util.response :as resp]
+            [stencil.core :as stencil]
             [metabase.api.routes :as api]
-            [metabase.setup :as setup]))
+            [metabase.setup :as setup]
+            [metabase.util :as u]))
+
+(defn- load-index-template
+  "Slurp in the Metabase index.html file as a `String`"
+  []
+  (slurp (clojure.java.io/resource "frontend_client/index.html")))
+
+(def load-index
+  "Memoized version of `load-index-template`"
+  ;(memoize load-index-template)
+  load-index-template)
+
+(def date-format-rfc2616
+  "Java SimpleDateFormat representing rfc2616 style date used in http headers."
+  "EEE, dd MMM yyyy HH:mm:ss zzz")
+
+(def index-page-vars
+  "Static values that we inject into the index.html page via Mustache."
+  {:ga_code "UA-60817802-1"})
 
 ;; Redirect naughty users who try to visit a page other than setup if setup is not yet complete
 (let [redirect-to-setup? (fn [{:keys [uri]}]
@@ -11,7 +31,9 @@
                                 (not (re-matches #"^/setup/.*$" uri))))
       index (fn [request]
               (if (redirect-to-setup? request) (resp/redirect (format "/setup/init/%s" (setup/token-value)))
-                  (resp/resource-response "frontend_client/index.html")))]
+                  (-> (resp/response (stencil/render-string (load-index) index-page-vars))
+                      (resp/content-type "text/html")
+                      (resp/header "Last-Modified" (u/now-with-format date-format-rfc2616)))))]
   (defroutes routes
     (GET "/" [] index)                                     ; ^/$           -> index.html
     (GET "/favicon.ico" [] (resp/resource-response "frontend_client/favicon.ico"))