config: Update remote URL handling.

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

Index: logdog/appengine/coordinator/endpoints/services/getConfig.go
diff --git a/logdog/appengine/coordinator/endpoints/services/getConfig.go b/logdog/appengine/coordinator/endpoints/services/getConfig.go
index 576228d15dead9870849d76c7ff495b73631ab6e..c85671e0519982af2ab942696a0587ee3f5233df 100644
--- a/logdog/appengine/coordinator/endpoints/services/getConfig.go
+++ b/logdog/appengine/coordinator/endpoints/services/getConfig.go
@@ -10,6 +10,8 @@ import (
 	"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"
+	"github.com/luci/luci-go/luci_config/appengine/gaeconfig"
+
 	"golang.org/x/net/context"
 )
 
@@ -18,15 +20,24 @@ import (
 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.")
+		log.WithError(err).Errorf(c, "Failed to load configuration.")
+		return nil, grpcutil.Internal
+	}
+
+	// Load our config service host from settings.
+	settings, err := gaeconfig.FetchCachedSettings(c)
+	if err != nil {
+		log.WithError(err).Errorf(c, "Failed to load settings.")
 		return nil, grpcutil.Internal
 	}
 
 	return &logdog.GetConfigResponse{
-		ConfigServiceUrl:  gcfg.ConfigServiceURL.String(),
+		ConfigServiceHost: settings.ConfigServiceHost,
 		ConfigSet:         string(gcfg.ConfigSet),
 		ServiceConfigPath: gcfg.ServiceConfigPath,
+
+		// TODO(dnj): Deprecate this field once everything has switched over to
+		// using host.
+		ConfigServiceUrl: gcfg.ConfigServiceURL.String(),
 	}, nil
 }