Revert "Revert "Add Bind extension point of the scheduling framework""

This reverts commit b8950dab50.

pkg/scheduler/framework/v1alpha1/framework.go

@@ -39,6 +39,7 @@ type framework struct {
 	prefilterPlugins []PrefilterPlugin
 	reservePlugins   []ReservePlugin
 	prebindPlugins   []PrebindPlugin
+	bindPlugins      []BindPlugin
 	postbindPlugins  []PostbindPlugin
 	unreservePlugins []UnreservePlugin
 	permitPlugins    []PermitPlugin
@@ -128,6 +129,20 @@ func NewFramework(r Registry, plugins *config.Plugins, args []config.PluginConfi
 		}
 	}
 
+	if plugins.Bind != nil {
+		for _, pb := range plugins.Bind.Enabled {
+			if pg, ok := f.plugins[pb.Name]; ok {
+				p, ok := pg.(BindPlugin)
+				if !ok {
+					return nil, fmt.Errorf("plugin %v does not extend bind plugin", pb.Name)
+				}
+				f.bindPlugins = append(f.bindPlugins, p)
+			} else {
+				return nil, fmt.Errorf("bind plugin %v does not exist", pb.Name)
+			}
+		}
+	}
+
 	if plugins.PostBind != nil {
 		for _, pb := range plugins.PostBind.Enabled {
 			if pg, ok := f.plugins[pb.Name]; ok {
@@ -243,6 +258,27 @@ func (f *framework) RunPrebindPlugins(
 	return nil
 }
 
+// RunBindPlugins runs the set of configured bind plugins until one returns a non `Skip` status.
+func (f *framework) RunBindPlugins(pc *PluginContext, pod *v1.Pod, nodeName string) *Status {
+	if len(f.bindPlugins) == 0 {
+		return NewStatus(Skip, "")
+	}
+	var status *Status
+	for _, bp := range f.bindPlugins {
+		status = bp.Bind(pc, pod, nodeName)
+		if status != nil && status.Code() == Skip {
+			continue
+		}
+		if !status.IsSuccess() {
+			msg := fmt.Sprintf("bind plugin %v failed to bind pod %v/%v: %v", bp.Name(), pod.Namespace, pod.Name, status.Message())
+			klog.Error(msg)
+			return NewStatus(Error, msg)
+		}
+		return status
+	}
+	return status
+}
+
 // RunPostbindPlugins runs the set of configured postbind plugins.
 func (f *framework) RunPostbindPlugins(
 	pc *PluginContext, pod *v1.Pod, nodeName string) {

pkg/scheduler/framework/v1alpha1/interface.go

@@ -42,6 +42,8 @@ const (
 	Unschedulable
 	// Wait is used when a permit plugin finds a pod scheduling should wait.
 	Wait
+	// Skip is used when a bind plugin chooses to skip binding.
+	Skip
 )
 
 // Status indicates the result of running a plugin. It consists of a code and a
@@ -192,6 +194,17 @@ type PermitPlugin interface {
 	Permit(pc *PluginContext, p *v1.Pod, nodeName string) (*Status, time.Duration)
 }
 
+// BindPlugin is an interface that must be implemented by "bind" plugins. Bind
+// plugins are used to bind a pod to a Node.
+type BindPlugin interface {
+	Plugin
+	// Bind plugins will not be called until all pre-bind plugins have completed. Each
+	// bind plugin is called in the configured order. A bind plugin may choose whether
+	// or not to handle the given Pod. If a bind plugin chooses to handle a Pod, the
+	// remaining bind plugins are skipped.
+	Bind(pc *PluginContext, p *v1.Pod, nodeName string) *Status
+}
+
 // Framework manages the set of plugins in use by the scheduling framework.
 // Configured plugins are called at specified points in a scheduling context.
 type Framework interface {
@@ -231,6 +244,13 @@ type Framework interface {
 	// Note that if multiple plugins asked to wait, then we wait for the minimum
 	// timeout duration.
 	RunPermitPlugins(pc *PluginContext, pod *v1.Pod, nodeName string) *Status
+
+	// RunBindPlugins runs the set of configured bind plugins. A bind plugin may choose
+	// whether or not to handle the given Pod. If a bind plugin chooses to skip the
+	// binding, it should return code=4("skip") status. Otherwise, it should return "Error"
+	// or "Success". If none of the plugins handled binding, RunBindPlugins returns
+	// code=4("skip") status.
+	RunBindPlugins(pc *PluginContext, pod *v1.Pod, nodeName string) *Status
 }
 
 // FrameworkHandle provides data and some tools that plugins can use. It is

pkg/scheduler/internal/queue/scheduling_queue_test.go

@@ -175,6 +175,10 @@ func (*fakeFramework) RunPrebindPlugins(pc *framework.PluginContext, pod *v1.Pod
 	return nil
 }
 
+func (*fakeFramework) RunBindPlugins(pc *framework.PluginContext, pod *v1.Pod, nodeName string) *framework.Status {
+	return nil
+}
+
 func (*fakeFramework) RunPostbindPlugins(pc *framework.PluginContext, pod *v1.Pod, nodeName string) {}
 
 func (*fakeFramework) RunReservePlugins(pc *framework.PluginContext, pod *v1.Pod, nodeName string) *framework.Status {

pkg/scheduler/scheduler.go

@@ -415,11 +415,25 @@ func (sched *Scheduler) assume(assumed *v1.Pod, host string) error {
 
 // bind binds a pod to a given node defined in a binding object.  We expect this to run asynchronously, so we
 // handle binding metrics internally.
-func (sched *Scheduler) bind(assumed *v1.Pod, b *v1.Binding) error {
+func (sched *Scheduler) bind(assumed *v1.Pod, targetNode string, pluginContext *framework.PluginContext) error {
 	bindingStart := time.Now()
-	// If binding succeeded then PodScheduled condition will be updated in apiserver so that
-	// it's atomic with setting host.
-	err := sched.config.GetBinder(assumed).Bind(b)
+	bindStatus := sched.config.Framework.RunBindPlugins(pluginContext, assumed, targetNode)
+	var err error
+	if bindStatus != nil && bindStatus.Code() == framework.Skip {
+		// All bind plugins chooses to skip binding of this pod, call original binding func.
+
+		// If binding succeeded then PodScheduled condition will be updated in apiserver so that
+		// it's atomic with setting host.
+		err = sched.config.GetBinder(assumed).Bind(&v1.Binding{
+			ObjectMeta: metav1.ObjectMeta{Namespace: assumed.Namespace, Name: assumed.Name, UID: assumed.UID},
+			Target: v1.ObjectReference{
+				Kind: "Node",
+				Name: targetNode,
+			},
+		})
+	} else if !bindStatus.IsSuccess() {
+		err = fmt.Errorf("scheduler RunBindPlugins failed for pod %v/%v: code %d, err %v", assumed.Namespace, assumed.Name, bindStatus.Code(), err)
+	}
 	if finErr := sched.config.SchedulerCache.FinishBinding(assumed); finErr != nil {
 		klog.Errorf("scheduler cache FinishBinding failed: %v", finErr)
 	}
@@ -437,7 +451,7 @@ func (sched *Scheduler) bind(assumed *v1.Pod, b *v1.Binding) error {
 	metrics.DeprecatedBindingLatency.Observe(metrics.SinceInMicroseconds(bindingStart))
 	metrics.SchedulingLatency.WithLabelValues(metrics.Binding).Observe(metrics.SinceInSeconds(bindingStart))
 	metrics.DeprecatedSchedulingLatency.WithLabelValues(metrics.Binding).Observe(metrics.SinceInSeconds(bindingStart))
-	sched.config.Recorder.Eventf(assumed, nil, v1.EventTypeNormal, "Scheduled", "Binding", "Successfully assigned %v/%v to %v", assumed.Namespace, assumed.Name, b.Target.Name)
+	sched.config.Recorder.Eventf(assumed, nil, v1.EventTypeNormal, "Scheduled", "Binding", "Successfully assigned %v/%v to %v", assumed.Namespace, assumed.Name, targetNode)
 	return nil
 }
 
@@ -578,13 +592,7 @@ func (sched *Scheduler) scheduleOne() {
 			return
 		}
 
-		err := sched.bind(assumedPod, &v1.Binding{
-			ObjectMeta: metav1.ObjectMeta{Namespace: assumedPod.Namespace, Name: assumedPod.Name, UID: assumedPod.UID},
-			Target: v1.ObjectReference{
-				Kind: "Node",
-				Name: scheduleResult.SuggestedHost,
-			},
-		})
+		err := sched.bind(assumedPod, scheduleResult.SuggestedHost, pluginContext)
 		metrics.E2eSchedulingLatency.Observe(metrics.SinceInSeconds(start))
 		metrics.DeprecatedE2eSchedulingLatency.Observe(metrics.SinceInMicroseconds(start))
 		if err != nil {

test/integration/scheduler/framework_test.go

@@ -22,8 +22,10 @@ import (
 	"time"
 
 	v1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/wait"
+	clientset "k8s.io/client-go/kubernetes"
 	schedulerconfig "k8s.io/kubernetes/pkg/scheduler/apis/config"
 	framework "k8s.io/kubernetes/pkg/scheduler/framework/v1alpha1"
 )
@@ -45,6 +47,13 @@ type PrebindPlugin struct {
 	rejectPrebind    bool
 }
 
+type BindPlugin struct {
+	numBindCalled int
+	PluginName string
+	bindStatus *framework.Status
+	client *clientset.Clientset
+}
+
 type PostbindPlugin struct {
 	numPostbindCalled int
 }
@@ -75,6 +84,7 @@ const (
 var _ = framework.PrefilterPlugin(&PrefilterPlugin{})
 var _ = framework.ReservePlugin(&ReservePlugin{})
 var _ = framework.PrebindPlugin(&PrebindPlugin{})
+var _ = framework.BindPlugin(&BindPlugin{})
 var _ = framework.PostbindPlugin(&PostbindPlugin{})
 var _ = framework.UnreservePlugin(&UnreservePlugin{})
 var _ = framework.PermitPlugin(&PermitPlugin{})
@@ -132,11 +142,38 @@ func (pp *PrebindPlugin) reset() {
 	pp.rejectPrebind = false
 }
 
+const bindPluginAnnotation = "bindPluginName"
+
 // NewPrebindPlugin is the factory for prebind plugin.
 func NewPrebindPlugin(_ *runtime.Unknown, _ framework.FrameworkHandle) (framework.Plugin, error) {
 	return pbdPlugin, nil
 }
 
+func (bp *BindPlugin) Name() string {
+	return bp.PluginName
+}
+
+func (bp *BindPlugin) Bind(pc *framework.PluginContext, p *v1.Pod, nodeName string) *framework.Status {
+	bp.numBindCalled++
+	if bp.bindStatus.IsSuccess() {
+		if err := bp.client.CoreV1().Pods(p.Namespace).Bind(&v1.Binding{
+			ObjectMeta: metav1.ObjectMeta{Namespace: p.Namespace, Name: p.Name, UID: p.UID, Annotations: map[string]string{bindPluginAnnotation: bp.Name()}},
+			Target: v1.ObjectReference{
+				Kind: "Node",
+				Name: nodeName,
+			},
+		}); err != nil {
+			return framework.NewStatus(framework.Error, fmt.Sprintf("bind failed: %v", err))
+		}
+	}
+	return bp.bindStatus
+}
+
+// reset used to reset numBindCalled.
+func (bp *BindPlugin) reset() {
+	bp.numBindCalled = 0
+}
+
 var ptbdPlugin = &PostbindPlugin{}
 
 // Name returns name of the plugin.
@@ -616,6 +653,165 @@ func TestUnreservePlugin(t *testing.T) {
 	}
 }
 
+// TestBindPlugin tests invocation of bind plugins.
+func TestBindPlugin(t *testing.T) {
+	testContext := initTestMaster(t, "bind-plugin", nil)
+	bindPlugin1, bindPlugin2 := &BindPlugin{PluginName: "bind-plugin-1", client: testContext.clientSet}, &BindPlugin{PluginName: "bind-plugin-2", client: testContext.clientSet}
+	// Create a plugin registry for testing. Register an unreserve, a bind plugin and a postBind plugin.
+	registry := framework.Registry{
+		unreservePluginName: NewUnreservePlugin,
+		bindPlugin1.Name(): func(_ *runtime.Unknown, _ framework.FrameworkHandle) (framework.Plugin, error) {
+			return bindPlugin1, nil
+		},
+		bindPlugin2.Name(): func(_ *runtime.Unknown, _ framework.FrameworkHandle) (framework.Plugin, error) {
+			return bindPlugin2, nil
+		},
+		postbindPluginName: NewPostbindPlugin,
+	}
+
+	// Setup initial unreserve and bind plugins for testing.
+	plugins := &schedulerconfig.Plugins{
+		Unreserve: &schedulerconfig.PluginSet{
+			Enabled: []schedulerconfig.Plugin{{Name: unreservePluginName}},
+		},
+		Bind: &schedulerconfig.PluginSet{
+			Enabled: []schedulerconfig.Plugin{{Name: bindPlugin1.Name()}, {Name: bindPlugin2.Name()}},
+		},
+		PostBind: &schedulerconfig.PluginSet{
+			Enabled: []schedulerconfig.Plugin{{Name: postbindPluginName}},
+		},
+	}
+	// Set reserve and bind config for testing
+	pluginConfig := []schedulerconfig.PluginConfig{
+		{
+			Name: unreservePluginName,
+			Args: runtime.Unknown{},
+		},
+		{
+			Name: bindPlugin1.Name(),
+			Args: runtime.Unknown{},
+		},
+		{
+			Name: bindPlugin2.Name(),
+			Args: runtime.Unknown{},
+		},
+		{
+			Name: postbindPluginName,
+			Args: runtime.Unknown{},
+		},
+	}
+
+	// Create the master and the scheduler with the test plugin set.
+	context := initTestSchedulerWithOptions(t, testContext,
+		false, nil, registry, plugins, pluginConfig, false, time.Second)
+	defer cleanupTest(t, context)
+
+	cs := context.clientSet
+	// Add a few nodes.
+	_, err := createNodes(cs, "test-node", nil, 2)
+	if err != nil {
+		t.Fatalf("Cannot create nodes: %v", err)
+	}
+
+	tests := []struct {
+		bindPluginStatuses     []*framework.Status
+		expectBoundByScheduler bool   // true means this test case expecting scheduler would bind pods
+		expectBoundByPlugin    bool   // true means this test case expecting a plugin would bind pods
+		expectBindPluginName   string // expecting plugin name to bind pods
+	}{
+		// bind plugins skiped to bind the pod and scheduler binded the pod
+		{
+			bindPluginStatuses:     []*framework.Status{framework.NewStatus(framework.Skip, ""), framework.NewStatus(framework.Skip, "")},
+			expectBoundByScheduler: true,
+		},
+		// bindplugin2 succeeded to bind the pod
+		{
+			bindPluginStatuses:   []*framework.Status{framework.NewStatus(framework.Skip, ""), framework.NewStatus(framework.Success, "")},
+			expectBoundByPlugin:  true,
+			expectBindPluginName: bindPlugin2.Name(),
+		},
+		// bindplugin1 succeeded to bind the pod
+		{
+			bindPluginStatuses:   []*framework.Status{framework.NewStatus(framework.Success, ""), framework.NewStatus(framework.Success, "")},
+			expectBoundByPlugin:  true,
+			expectBindPluginName: bindPlugin1.Name(),
+		},
+		// bind plugin fails to bind the pod
+		{
+			bindPluginStatuses: []*framework.Status{framework.NewStatus(framework.Error, "failed to bind"), framework.NewStatus(framework.Success, "")},
+		},
+	}
+
+	for i, test := range tests {
+		bindPlugin1.bindStatus = test.bindPluginStatuses[0]
+		bindPlugin2.bindStatus = test.bindPluginStatuses[1]
+
+		// Create a best effort pod.
+		pod, err := createPausePod(cs,
+			initPausePod(cs, &pausePodConfig{Name: "test-pod", Namespace: context.ns.Name}))
+		if err != nil {
+			t.Errorf("Error while creating a test pod: %v", err)
+		}
+
+		if test.expectBoundByScheduler || test.expectBoundByPlugin {
+			// bind plugins skiped to bind the pod
+			if err = waitForPodToSchedule(cs, pod); err != nil {
+				t.Errorf("test #%v: Expected the pod to be scheduled. error: %v", i, err)
+				continue
+			}
+			pod, err = cs.CoreV1().Pods(pod.Namespace).Get(pod.Name, metav1.GetOptions{})
+			if err != nil {
+				t.Errorf("can't get pod: %v", err)
+			}
+			if test.expectBoundByScheduler {
+				if pod.Annotations[bindPluginAnnotation] != "" {
+					t.Errorf("test #%v: Expected the pod to be binded by scheduler instead of by bindplugin %s", i, pod.Annotations[bindPluginAnnotation])
+				}
+				if bindPlugin1.numBindCalled != 1 || bindPlugin2.numBindCalled != 1 {
+					t.Errorf("test #%v: Expected each bind plugin to be called once, was called %d and %d times.", i, bindPlugin1.numBindCalled, bindPlugin2.numBindCalled)
+				}
+			} else {
+				if pod.Annotations[bindPluginAnnotation] != test.expectBindPluginName {
+					t.Errorf("test #%v: Expected the pod to be binded by bindplugin %s instead of by bindplugin %s", i, test.expectBindPluginName, pod.Annotations[bindPluginAnnotation])
+				}
+				if bindPlugin1.numBindCalled != 1 {
+					t.Errorf("test #%v: Expected %s to be called once, was called %d times.", i, bindPlugin1.Name(), bindPlugin1.numBindCalled)
+				}
+				if test.expectBindPluginName == bindPlugin1.Name() && bindPlugin2.numBindCalled > 0 {
+					// expect bindplugin1 succeeded to bind the pod and bindplugin2 should not be called.
+					t.Errorf("test #%v: Expected %s not to be called, was called %d times.", i, bindPlugin2.Name(), bindPlugin1.numBindCalled)
+				}
+			}
+			if err = wait.Poll(10*time.Millisecond, 30*time.Second, func() (done bool, err error) {
+				return ptbdPlugin.numPostbindCalled == 1, nil
+			}); err != nil {
+				t.Errorf("test #%v: Expected the postbind plugin to be called once, was called %d times.", i, ptbdPlugin.numPostbindCalled)
+			}
+			if unresPlugin.numUnreserveCalled != 0 {
+				t.Errorf("test #%v: Expected the unreserve plugin not to be called, was called %d times.", i, unresPlugin.numUnreserveCalled)
+			}
+		} else {
+			// bind plugin fails to bind the pod
+			if err = wait.Poll(10*time.Millisecond, 30*time.Second, podSchedulingError(cs, pod.Namespace, pod.Name)); err != nil {
+				t.Errorf("test #%v: Expected a scheduling error, but didn't get it. error: %v", i, err)
+			}
+			if ptbdPlugin.numPostbindCalled > 0 {
+				t.Errorf("test #%v: Didn't expected the postbind plugin to be called %d times.", i, ptbdPlugin.numPostbindCalled)
+			}
+			if err = wait.Poll(10*time.Millisecond, 30*time.Second, func() (done bool, err error) {
+				return unresPlugin.numUnreserveCalled == 1, nil
+			}); err != nil {
+				t.Errorf("test #%v: Expected the unreserve plugin to be called once, was called %d times.", i, unresPlugin.numUnreserveCalled)
+			}
+		}
+		ptbdPlugin.reset()
+		bindPlugin1.reset()
+		bindPlugin2.reset()
+		unresPlugin.reset()
+		cleanupPods(cs, t, []*v1.Pod{pod})
+	}
+}
+
 // TestPostbindPlugin tests invocation of postbind plugins.
 func TestPostbindPlugin(t *testing.T) {
 	// Create a plugin registry for testing. Register a prebind and a postbind plugin.