Add server/cache support to gaeconfig.

logdog/appengine/coordinator/endpoints/services/getConfig.go

 // Copyright 2015 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 services
 
 import (
         log "github.com/luci/luci-go/common/logging"
         "github.com/luci/luci-go/common/proto/google"
         "github.com/luci/luci-go/grpc/grpcutil"
         "github.com/luci/luci-go/logdog/api/endpoints/coordinator/services/v1"
         "github.com/luci/luci-go/logdog/appengine/coordinator"
         "golang.org/x/net/context"
 )
 
 // GetConfig allows a service to retrieve the current service configuration
 // parameters.
 func (s *server) GetConfig(c context.Context, req *google.Empty) (*logdog.GetConfigResponse, error) {
         gcfg, err := coordinator.GetServices(c).Config(c)
         if err != nil {
                 log.Fields{
                         log.ErrorKey: err,
                 }.Errorf(c, "Failed to load configuration.")
                 return nil, grpcutil.Internal
         }
 
         return &logdog.GetConfigResponse{
                 ConfigServiceUrl:  gcfg.ConfigServiceURL.String(),
-                ConfigSet:         gcfg.ConfigSet,
+                ConfigSet:         string(gcfg.ConfigSet),
                 ServiceConfigPath: gcfg.ServiceConfigPath,
         }, nil
 }