From a63bd1bdfa1b15b230e9d6089d87602577dffbca Mon Sep 17 00:00:00 2001
From: Daniel Smith <dbsmith@google.com>
Date: Thu, 18 Dec 2014 17:47:59 -0800
Subject: [PATCH] Remove an unneeded trip over the network when getting/listing
 pods.

---
 pkg/master/master.go        | 14 ++++--
 pkg/master/rest_to_nodes.go | 85 +++++++++++++++++++++++++++++++++++++
 2 files changed, 96 insertions(+), 3 deletions(-)
 create mode 100644 pkg/master/rest_to_nodes.go

diff --git a/pkg/master/master.go b/pkg/master/master.go
index 94b1ca55261..866191c00e1 100644
--- a/pkg/master/master.go
+++ b/pkg/master/master.go
@@ -325,6 +325,8 @@ func (m *Master) init(c *Config) {
 	var userContexts = handlers.NewUserRequestContext()
 	var authenticator = c.Authenticator
 
+	nodeRESTStorage := minion.NewREST(m.minionRegistry)
+
 	// TODO: Factor out the core API registration
 	m.storage = map[string]apiserver.RESTStorage{
 		"pods": pod.NewREST(&pod.RESTConfig{
@@ -332,13 +334,19 @@ func (m *Master) init(c *Config) {
 			PodCache:      podCache,
 			PodInfoGetter: c.KubeletClient,
 			Registry:      m.podRegistry,
-			Nodes:         m.client.Nodes(),
+			// Note: this allows the pod rest object to directly call
+			// the node rest object without going through the network &
+			// apiserver. This arrangement should be temporary, nodes
+			// shouldn't really need this at all. Once we add more auth in,
+			// we need to consider carefully if this sort of shortcut is a
+			// good idea.
+			Nodes: RESTStorageToNodes(nodeRESTStorage).Nodes(),
 		}),
 		"replicationControllers": controller.NewREST(m.controllerRegistry, m.podRegistry),
 		"services":               service.NewREST(m.serviceRegistry, c.Cloud, m.minionRegistry, m.portalNet),
 		"endpoints":              endpoint.NewREST(m.endpointRegistry),
-		"minions":                minion.NewREST(m.minionRegistry),
-		"nodes":                  minion.NewREST(m.minionRegistry),
+		"minions":                nodeRESTStorage,
+		"nodes":                  nodeRESTStorage,
 		"events":                 event.NewREST(m.eventRegistry),
 
 		// TODO: should appear only in scheduler API group.
diff --git a/pkg/master/rest_to_nodes.go b/pkg/master/rest_to_nodes.go
new file mode 100644
index 00000000000..a86a7eea90b
--- /dev/null
+++ b/pkg/master/rest_to_nodes.go
@@ -0,0 +1,85 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package master
+
+import (
+	"errors"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/apiserver"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/client"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/labels"
+)
+
+// RESTStorageToNodes will take a RESTStorage object and return a client interface
+// which will work for any use expecting a client.Nodes() interface. The advantage
+// of doing this in server code is that it doesn't require an actual trip through
+// the network.
+//
+// TODO: considering that the only difference between the various client types
+// and RESTStorage type is the type of the arguments, maybe use "go generate" to
+// write a specialized adaptor for every client type?
+func RESTStorageToNodes(storage apiserver.RESTStorage) client.NodesInterface {
+	return &nodeAdaptor{storage}
+}
+
+type nodeAdaptor struct {
+	storage apiserver.RESTStorage
+}
+
+func (n *nodeAdaptor) Nodes() client.NodeInterface {
+	return n
+}
+
+// Create creates a new minion.
+func (n *nodeAdaptor) Create(minion *api.Node) (*api.Node, error) {
+	return nil, errors.New("direct creation not implemented")
+	// TODO: apiserver should expose newOperation to make this easier.
+	// the actual code that should go here would start like this:
+	//
+	// ctx := api.NewDefaultContext()
+	// out, err := n.storage.Create(ctx, minion)
+	// if err != nil {
+	//	return nil, err
+	// }
+}
+
+// List lists all the nodes in the cluster.
+func (n *nodeAdaptor) List() (*api.NodeList, error) {
+	ctx := api.NewContext()
+	obj, err := n.storage.List(ctx, labels.Everything(), labels.Everything())
+	if err != nil {
+		return nil, err
+	}
+	return obj.(*api.NodeList), nil
+}
+
+// Get gets an existing minion
+func (n *nodeAdaptor) Get(name string) (*api.Node, error) {
+	ctx := api.NewContext()
+	obj, err := n.storage.Get(ctx, name)
+	if err != nil {
+		return nil, err
+	}
+	return obj.(*api.Node), nil
+}
+
+// Delete deletes an existing minion.
+// TODO: implement
+func (n *nodeAdaptor) Delete(name string) error {
+	return errors.New("direct deletion not implemented")
+}