Milo: Use custom config caching layer

milo/appengine/frontend/frontpage.go

 // Copyright 2016 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package frontend
 
 import (
-        "net/http"
-
         "github.com/luci/luci-go/server/router"
         "github.com/luci/luci-go/server/templates"
 
         "github.com/luci/luci-go/common/sync/parallel"
         "github.com/luci/luci-go/milo/api/resp"
         "github.com/luci/luci-go/milo/appengine/buildbot"
         "github.com/luci/luci-go/milo/appengine/buildbucket"
         "github.com/luci/luci-go/milo/appengine/common"
 )
 
 func frontpageHandler(c *router.Context) {
         fp := resp.FrontPage{}
         var mBuildbot, mBuildbucket *resp.CIService
 
         err := parallel.FanOutIn(func(ch chan<- func() error) {
                 ch <- func() (err error) {
                         mBuildbot, err = buildbot.GetAllBuilders(c.Context)
                         return err
                 }
                 ch <- func() (err error) {
                         mBuildbucket, err = buildbucket.GetAllBuilders(c.Context)
                         return err
                 }
         })
-        if err != nil {
-                common.ErrorPage(c, http.StatusInternalServerError, err.Error())
-                return
-        }
 
         fp.CIServices = append(fp.CIServices, *mBuildbucket)
         fp.CIServices = append(fp.CIServices, *mBuildbot)
         templates.MustRender(c.Context, c.Writer, "pages/frontpage.html", templates.Args{
                 "frontpage": fp,
+                "error":     err.Error(),
         })
 }
 
 func frontpageTestData() []common.TestBundle {
         data := &templates.Args{
                 "frontpage": resp.FrontPage{
                         CIServices: []resp.CIService{
                                 {
                                         Name: "Module 1",
                                         BuilderGroups: []resp.BuilderGroup{
                                                 {
                                                         Name: "Example master A",
                                                         Builders: []resp.Link{
                                                                 {
                                                                         Label: "Example builder",
                                                                         URL:   "/master1/buildera",
                                                                 },
                                                                 {
                                                                         Label: "Example builder 2",
                                                                         URL:   "/master1/builderb",
                                                                 },
                                                         },
                                                 },
                                         },
                                 },
                         },
                 },
+                "error": "couldn't find ice cream",
         }
         return []common.TestBundle{
                 {
                         Description: "Basic frontpage",
                         Data:        *data,
                 },
         }
 }