Milo: Use custom config caching layer

milo/appengine/buildbucket/buckets.go

 // Copyright 2017 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 buildbucket
 
 import (
         "errors"
         "fmt"
 
         "golang.org/x/net/context"
 
-        "github.com/luci/luci-go/common/logging"
         "github.com/luci/luci-go/milo/api/resp"
         "github.com/luci/luci-go/milo/appengine/common"
 )
 
 func GetAllBuilders(c context.Context) (*resp.CIService, error) {
-        settings, err := common.GetSettings(c)
-        if err != nil {
-                logging.WithError(err).Errorf(c, "could not get settings for buildbucket")
-                return nil, err
-        }
+        settings := common.GetSettings(c)
         bucketSettings := settings.Buildbucket
         if bucketSettings == nil {
                 return nil, errors.New("buildbucket settings missing in config")
         }
         result := &resp.CIService{
                 Name: "Swarmbucket",
                 Host: &resp.Link{
                         Label: bucketSettings.Name,
                         URL:   "https://" + bucketSettings.Host,
                 },
@@ skipping 16 matching lines @@
                         group.Builders[j] = resp.Link{
                                 Label: builder.Name,
                                 URL:   fmt.Sprintf("/buildbucket/%s/%s", bucket.Name, builder.Name),
                         }
                 }
                 result.BuilderGroups[i] = group
         }
 
         return result, nil
 }