Move controller to it's own package, it's not part of the registry.

pkg/controller/replication_controller.go

@@ -0,0 +1,199 @@
+/*
+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 controller
+
+import (
+	"encoding/json"
+	"fmt"
+	"log"
+	"math/rand"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/client"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
+	"github.com/coreos/go-etcd/etcd"
+)
+
+// ReplicationManager is responsible for synchronizing ReplicationController objects stored in etcd
+// with actual running pods.
+// TODO: Remove the etcd dependency and re-factor in terms of a generic watch interface
+type ReplicationManager struct {
+	etcdClient *etcd.Client
+	kubeClient client.ClientInterface
+	podControl PodControlInterface
+	updateLock sync.Mutex
+}
+
+// An interface that knows how to add or delete pods
+// created as an interface to allow testing.
+type PodControlInterface interface {
+	createReplica(controllerSpec api.ReplicationController)
+	deletePod(podID string) error
+}
+
+type RealPodControl struct {
+	kubeClient client.ClientInterface
+}
+
+func (r RealPodControl) createReplica(controllerSpec api.ReplicationController) {
+	labels := controllerSpec.DesiredState.PodTemplate.Labels
+	if labels != nil {
+		labels["replicationController"] = controllerSpec.ID
+	}
+	pod := api.Pod{
+		JSONBase: api.JSONBase{
+			ID: fmt.Sprintf("%x", rand.Int()),
+		},
+		DesiredState: controllerSpec.DesiredState.PodTemplate.DesiredState,
+		Labels:       controllerSpec.DesiredState.PodTemplate.Labels,
+	}
+	_, err := r.kubeClient.CreatePod(pod)
+	if err != nil {
+		log.Printf("%#v\n", err)
+	}
+}
+
+func (r RealPodControl) deletePod(podID string) error {
+	return r.kubeClient.DeletePod(podID)
+}
+
+func MakeReplicationManager(etcdClient *etcd.Client, kubeClient client.ClientInterface) *ReplicationManager {
+	return &ReplicationManager{
+		kubeClient: kubeClient,
+		etcdClient: etcdClient,
+		podControl: RealPodControl{
+			kubeClient: kubeClient,
+		},
+	}
+}
+
+func (rm *ReplicationManager) WatchControllers() {
+	watchChannel := make(chan *etcd.Response)
+	go func() {
+		defer util.HandleCrash()
+		defer func() {
+			close(watchChannel)
+		}()
+		rm.etcdClient.Watch("/registry/controllers", 0, true, watchChannel, nil)
+	}()
+
+	for {
+		watchResponse, ok := <-watchChannel
+		if !ok {
+			// watchChannel has been closed. Let the util.Forever() that
+			// called us call us again.
+			return
+		}
+		if watchResponse == nil {
+			time.Sleep(time.Second * 10)
+			continue
+		}
+		log.Printf("Got watch: %#v", watchResponse)
+		controller, err := rm.handleWatchResponse(watchResponse)
+		if err != nil {
+			log.Printf("Error handling data: %#v, %#v", err, watchResponse)
+			continue
+		}
+		rm.syncReplicationController(*controller)
+	}
+}
+
+func (rm *ReplicationManager) handleWatchResponse(response *etcd.Response) (*api.ReplicationController, error) {
+	if response.Action == "set" {
+		if response.Node != nil {
+			var controllerSpec api.ReplicationController
+			err := json.Unmarshal([]byte(response.Node.Value), &controllerSpec)
+			if err != nil {
+				return nil, err
+			}
+			return &controllerSpec, nil
+		} else {
+			return nil, fmt.Errorf("response node is null %#v", response)
+		}
+	}
+	return nil, nil
+}
+
+func (rm *ReplicationManager) filterActivePods(pods []api.Pod) []api.Pod {
+	var result []api.Pod
+	for _, value := range pods {
+		if strings.Index(value.CurrentState.Status, "Exit") == -1 {
+			result = append(result, value)
+		}
+	}
+	return result
+}
+
+func (rm *ReplicationManager) syncReplicationController(controllerSpec api.ReplicationController) error {
+	rm.updateLock.Lock()
+	podList, err := rm.kubeClient.ListPods(controllerSpec.DesiredState.ReplicasInSet)
+	if err != nil {
+		return err
+	}
+	filteredList := rm.filterActivePods(podList.Items)
+	diff := len(filteredList) - controllerSpec.DesiredState.Replicas
+	log.Printf("%#v", filteredList)
+	if diff < 0 {
+		diff *= -1
+		log.Printf("Too few replicas, creating %d\n", diff)
+		for i := 0; i < diff; i++ {
+			rm.podControl.createReplica(controllerSpec)
+		}
+	} else if diff > 0 {
+		log.Print("Too many replicas, deleting")
+		for i := 0; i < diff; i++ {
+			rm.podControl.deletePod(filteredList[i].ID)
+		}
+	}
+	rm.updateLock.Unlock()
+	return nil
+}
+
+func (rm *ReplicationManager) Synchronize() {
+	for {
+		response, err := rm.etcdClient.Get("/registry/controllers", false, false)
+		if err != nil {
+			log.Printf("Synchronization error %#v", err)
+		}
+		// TODO(bburns): There is a race here, if we get a version of the controllers, and then it is
+		// updated, its possible that the watch will pick up the change first, and then we will execute
+		// using the old version of the controller.
+		// Probably the correct thing to do is to use the version number in etcd to detect when
+		// we are stale.
+		// Punting on this for now, but this could lead to some nasty bugs, so we should really fix it
+		// sooner rather than later.
+		if response != nil && response.Node != nil && response.Node.Nodes != nil {
+			for _, value := range response.Node.Nodes {
+				var controllerSpec api.ReplicationController
+				err := json.Unmarshal([]byte(value.Value), &controllerSpec)
+				if err != nil {
+					log.Printf("Unexpected error: %#v", err)
+					continue
+				}
+				log.Printf("Synchronizing %s\n", controllerSpec.ID)
+				err = rm.syncReplicationController(controllerSpec)
+				if err != nil {
+					log.Printf("Error synchronizing: %#v", err)
+				}
+			}
+		}
+		time.Sleep(10 * time.Second)
+	}
+}