Begin scheduler plugin

hack/build-go.sh

@@ -33,7 +33,7 @@ cd "${KUBE_REPO_ROOT}"
 
 if [[ $# == 0 ]]; then
   # Update $@ with the default list of targets to build.
-  set -- cmd/proxy cmd/apiserver cmd/controller-manager cmd/kubelet cmd/kubecfg
+  set -- cmd/proxy cmd/apiserver cmd/controller-manager cmd/kubelet cmd/kubecfg plugin/cmd/scheduler
 fi
 
 binaries=()

pkg/scheduler/listers.go

@@ -36,6 +36,7 @@ func (f FakeMinionLister) List() ([]string, error) {
 
 // PodLister interface represents anything that can list pods for a scheduler
 type PodLister interface {
+	// TODO: make this exactly the same as client's ListPods() method...
 	ListPods(labels.Selector) ([]api.Pod, error)
 }
 

pkg/scheduler/randomfit.go

@@ -57,6 +57,7 @@ func (s *RandomFitScheduler) Schedule(pod api.Pod, minionLister MinionLister) (s
 		return "", err
 	}
 	machineToPods := map[string][]api.Pod{}
+	// TODO: perform more targeted query...
 	pods, err := s.podLister.ListPods(labels.Everything())
 	if err != nil {
 		return "", err

plugin/cmd/scheduler/scheduler.go

@@ -0,0 +1,141 @@
+/*
+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 main
+
+import (
+	"flag"
+	"math/rand"
+	"time"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/client"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/client/cache"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/labels"
+	algorithm "github.com/GoogleCloudPlatform/kubernetes/pkg/scheduler"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
+	verflag "github.com/GoogleCloudPlatform/kubernetes/pkg/version/flag"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/watch"
+	"github.com/GoogleCloudPlatform/kubernetes/plugin/pkg/scheduler"
+)
+
+var (
+	master = flag.String("master", "", "The address of the Kubernetes API server")
+)
+
+// storeToMinionLister turns a store into a minion lister. The store must contain (only) minions.
+type storeToMinionLister struct {
+	s cache.Store
+}
+
+func (s storeToMinionLister) List() (machines []string, err error) {
+	for _, m := range s.s.List() {
+		machines = append(machines, m.(*api.Minion).ID)
+	}
+	return machines, nil
+}
+
+// storeToPodLister turns a store into a pod lister. The store must contain (only) pods.
+type storeToPodLister struct {
+	s cache.Store
+}
+
+func (s storeToPodLister) ListPods(selector labels.Selector) (pods []api.Pod, err error) {
+	for _, m := range s.s.List() {
+		pod := m.(*api.Pod)
+		if selector.Matches(labels.Set(pod.Labels)) {
+			pods = append(pods, *pod)
+		}
+	}
+	return pods, nil
+}
+
+type binder struct {
+	kubeClient *client.Client
+}
+
+// Bind just does a POST binding RPC.
+func (b binder) Bind(binding *api.Binding) error {
+	return b.kubeClient.Post().Path("bindings").Body(binding).Do().Error()
+}
+
+func main() {
+	flag.Parse()
+	util.InitLogs()
+	defer util.FlushLogs()
+
+	verflag.PrintAndExitIfRequested()
+
+	// This function is long because we inject all the dependencies into scheduler here.
+
+	// TODO: security story for plugins!
+	kubeClient := client.New("http://"+*master, nil)
+
+	// Watch and queue pods that need scheduling.
+	podQueue := cache.NewFIFO()
+	cache.NewReflector(func(resourceVersion uint64) (watch.Interface, error) {
+		// This query will only find pods with no assigned host.
+		return kubeClient.
+			Get().
+			Path("pods").
+			Path("watch").
+			SelectorParam("fields", labels.Set{"DesiredState.Host": ""}.AsSelector()).
+			UintParam("resourceVersion", resourceVersion).
+			Watch()
+	}, &api.Pod{}, podQueue).Run()
+
+	// Watch and cache all running pods. Scheduler needs to find all pods
+	// so it knows where it's safe to place a pod. Cache this locally.
+	podCache := cache.NewStore()
+	cache.NewReflector(func(resourceVersion uint64) (watch.Interface, error) {
+		// This query will only find pods that do have an assigned host.
+		return kubeClient.
+			Get().
+			Path("pods").
+			Path("watch").
+			ParseSelectorParam("fields", "DesiredState.Host!=").
+			UintParam("resourceVersion", resourceVersion).
+			Watch()
+	}, &api.Pod{}, podCache).Run()
+
+	// Watch minions.
+	// Minions may be listed frequently, so provide a local up-to-date cache.
+	minionCache := cache.NewStore()
+	cache.NewReflector(func(resourceVersion uint64) (watch.Interface, error) {
+		// This query will only find pods that do have an assigned host.
+		return kubeClient.
+			Get().
+			Path("minions").
+			Path("watch").
+			UintParam("resourceVersion", resourceVersion).
+			Watch()
+	}, &api.Minion{}, minionCache).Run()
+
+	r := rand.New(rand.NewSource(time.Now().UnixNano()))
+	algo := algorithm.NewRandomFitScheduler(
+		storeToPodLister{podCache}, r)
+
+	s := scheduler.New(&scheduler.Config{
+		MinionLister: storeToMinionLister{minionCache},
+		Algorithm:    algo,
+		NextPod:      func() *api.Pod { return podQueue.Pop().(*api.Pod) },
+		Binder:       binder{kubeClient},
+	})
+
+	s.Run()
+
+	select {}
+}

plugin/pkg/scheduler/scheduler.go

@@ -0,0 +1,80 @@
+/*
+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 scheduler
+
+import (
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
+	// TODO: move everything from pkg/scheduler into this package. Remove references from registry.
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/scheduler"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
+)
+
+// Binder knows how to write a binding.
+type Binder interface {
+	Bind(binding *api.Binding) error
+}
+
+// Scheduler watches for new unscheduled pods. It attempts to find
+// minions that they fit on and writes bindings back to the api server.
+type Scheduler struct {
+	c *Config
+}
+
+type Config struct {
+	MinionLister scheduler.MinionLister
+	Algorithm    scheduler.Scheduler
+	Binder       Binder
+
+	// NextPod should be a function that blocks until the next pod
+	// is available. We don't use a channel for this, because scheduling
+	// a pod may take some amount of time and we don't want pods to get
+	// stale while they sit in a channel.
+	NextPod func() *api.Pod
+
+	// Error is called if there is an error. It is passed the pod in
+	// question, and the error
+	Error func(*api.Pod, error)
+}
+
+// New returns a new scheduler.
+func New(c *Config) *Scheduler {
+	s := &Scheduler{
+		c: c,
+	}
+	return s
+}
+
+// Run begins watching and scheduling.
+func (s *Scheduler) Run() {
+	go util.Forever(s.scheduleOne, 0)
+}
+
+func (s *Scheduler) scheduleOne() {
+	pod := s.c.NextPod()
+	dest, err := s.c.Algorithm.Schedule(*pod, s.c.MinionLister)
+	if err != nil {
+		s.c.Error(pod, err)
+		return
+	}
+	b := &api.Binding{
+		PodID: pod.ID,
+		Host:  dest,
+	}
+	if err := s.c.Binder.Bind(b); err != nil {
+		s.c.Error(pod, err)
+	}
+}

plugin/pkg/scheduler/scheduler_test.go

@@ -0,0 +1,110 @@
+/*
+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 scheduler
+
+import (
+	"errors"
+	"reflect"
+	"testing"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/scheduler"
+)
+
+type fakeBinder struct {
+	b func(binding *api.Binding) error
+}
+
+func (fb fakeBinder) Bind(binding *api.Binding) error { return fb.b(binding) }
+
+func podWithID(id string) *api.Pod {
+	return &api.Pod{JSONBase: api.JSONBase{ID: "foo"}}
+}
+
+type mockScheduler struct {
+	machine string
+	err     error
+}
+
+func (es mockScheduler) Schedule(pod api.Pod, ml scheduler.MinionLister) (string, error) {
+	return es.machine, es.err
+}
+
+func TestScheduler(t *testing.T) {
+
+	errS := errors.New("scheduler")
+	errB := errors.New("binder")
+
+	table := []struct {
+		injectBindError error
+		sendPod         *api.Pod
+		algo            scheduler.Scheduler
+		expectErrorPod  *api.Pod
+		expectError     error
+		expectBind      *api.Binding
+	}{
+		{
+			sendPod:    podWithID("foo"),
+			algo:       mockScheduler{"machine1", nil},
+			expectBind: &api.Binding{PodID: "foo", Host: "machine1"},
+		}, {
+			sendPod:        podWithID("foo"),
+			algo:           mockScheduler{"machine1", errS},
+			expectError:    errS,
+			expectErrorPod: podWithID("foo"),
+		}, {
+			sendPod:         podWithID("foo"),
+			algo:            mockScheduler{"machine1", nil},
+			expectBind:      &api.Binding{PodID: "foo", Host: "machine1"},
+			injectBindError: errB,
+			expectError:     errB,
+			expectErrorPod:  podWithID("foo"),
+		},
+	}
+
+	for i, item := range table {
+		var gotError error
+		var gotPod *api.Pod
+		var gotBinding *api.Binding
+		c := &Config{
+			MinionLister: scheduler.FakeMinionLister{"machine1"},
+			Algorithm:    item.algo,
+			Binder: fakeBinder{func(b *api.Binding) error {
+				gotBinding = b
+				return item.injectBindError
+			}},
+			Error: func(p *api.Pod, err error) {
+				gotPod = p
+				gotError = err
+			},
+			NextPod: func() *api.Pod {
+				return item.sendPod
+			},
+		}
+		s := New(c)
+		s.scheduleOne()
+		if e, a := item.expectErrorPod, gotPod; !reflect.DeepEqual(e, a) {
+			t.Errorf("%v: error pod: wanted %v, got %v", i, e, a)
+		}
+		if e, a := item.expectError, gotError; !reflect.DeepEqual(e, a) {
+			t.Errorf("%v: error: wanted %v, got %v", i, e, a)
+		}
+		if e, a := item.expectBind, gotBinding; !reflect.DeepEqual(e, a) {
+			t.Errorf("%v: error: wanted %v, got %v", i, e, a)
+		}
+	}
+}