Begin scheduler plugin

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)
+		}
+	}
+}