Added Bind method to Scheduler Extender

- only one extender can support the bind method
- if an extender supports bind, scheduler delegates the pod binding to the extender

plugin/pkg/scheduler/algorithm/scheduler_interface.go

@@ -35,6 +35,12 @@ type SchedulerExtender interface {
 	// are used to compute the weighted score for an extender. The weighted scores are added to
 	// the scores computed  by Kubernetes scheduler. The total scores are used to do the host selection.
 	Prioritize(pod *v1.Pod, nodes []*v1.Node) (hostPriorities *schedulerapi.HostPriorityList, weight int, err error)
+
+	// Bind delegates the action of binding a pod to a node to the extender.
+	Bind(binding *v1.Binding) error
+
+	// IsBinder returns whether this extender is configured for the Bind method.
+	IsBinder() bool
 }
 
 // ScheduleAlgorithm is an interface implemented by things that know how to schedule pods

plugin/pkg/scheduler/api/BUILD

@@ -19,6 +19,7 @@ go_library(
         "//vendor/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/runtime:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/types:go_default_library",
         "//vendor/k8s.io/client-go/rest:go_default_library",
     ],
 )

plugin/pkg/scheduler/api/types.go

@@ -20,6 +20,7 @@ import (
 	"time"
 
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/types"
 	restclient "k8s.io/client-go/rest"
 	"k8s.io/kubernetes/pkg/api/v1"
 )
@@ -133,6 +134,10 @@ type ExtenderConfig struct {
 	// The numeric multiplier for the node scores that the prioritize call generates.
 	// The weight should be a positive integer
 	Weight int
+	// Verb for the bind call, empty if not supported. This verb is appended to the URLPrefix when issuing the bind call to extender.
+	// If this method is implemented by the extender, it is the extender's responsibility to bind the pod to apiserver. Only one extender
+	// can implement this function.
+	BindVerb string
 	// EnableHttps specifies whether https should be used to communicate with the extender
 	EnableHttps bool
 	// TLSConfig specifies the transport layer security config
@@ -176,6 +181,24 @@ type ExtenderFilterResult struct {
 	Error string
 }
 
+// ExtenderBindingArgs represents the arguments to an extender for binding a pod to a node.
+type ExtenderBindingArgs struct {
+	// PodName is the name of the pod being bound
+	PodName string
+	// PodNamespace is the namespace of the pod being bound
+	PodNamespace string
+	// PodUID is the UID of the pod being bound
+	PodUID types.UID
+	// Node selected by the scheduler
+	Node string
+}
+
+// ExtenderBindingResult represents the result of binding of a pod to a node from an extender.
+type ExtenderBindingResult struct {
+	// Error message indicating failure
+	Error string
+}
+
 // HostPriority represents the priority of scheduling to a particular host, higher priority is better.
 type HostPriority struct {
 	// Name of the host

plugin/pkg/scheduler/api/v1/BUILD

@@ -20,6 +20,7 @@ go_library(
         "//vendor/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/runtime:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/types:go_default_library",
         "//vendor/k8s.io/client-go/rest:go_default_library",
     ],
 )

plugin/pkg/scheduler/api/v1/types.go

@@ -20,6 +20,7 @@ import (
 	"time"
 
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/types"
 	restclient "k8s.io/client-go/rest"
 	apiv1 "k8s.io/kubernetes/pkg/api/v1"
 )
@@ -125,6 +126,10 @@ type ExtenderConfig struct {
 	// The numeric multiplier for the node scores that the prioritize call generates.
 	// The weight should be a positive integer
 	Weight int `json:"weight,omitempty"`
+	// Verb for the bind call, empty if not supported. This verb is appended to the URLPrefix when issuing the bind call to extender.
+	// If this method is implemented by the extender, it is the extender's responsibility to bind the pod to apiserver. Only one extender
+	// can implement this function.
+	BindVerb string
 	// EnableHttps specifies whether https should be used to communicate with the extender
 	EnableHttps bool `json:"enableHttps,omitempty"`
 	// TLSConfig specifies the transport layer security config
@@ -168,6 +173,24 @@ type ExtenderFilterResult struct {
 	Error string `json:"error,omitempty"`
 }
 
+// ExtenderBindingArgs represents the arguments to an extender for binding a pod to a node.
+type ExtenderBindingArgs struct {
+	// PodName is the name of the pod being bound
+	PodName string
+	// PodNamespace is the namespace of the pod being bound
+	PodNamespace string
+	// PodUID is the UID of the pod being bound
+	PodUID types.UID
+	// Node selected by the scheduler
+	Node string
+}
+
+// ExtenderBindingResult represents the result of binding of a pod to a node from an extender.
+type ExtenderBindingResult struct {
+	// Error message indicating failure
+	Error string
+}
+
 // HostPriority represents the priority of scheduling to a particular host, higher priority is better.
 type HostPriority struct {
 	// Name of the host

plugin/pkg/scheduler/api/validation/validation.go

@@ -34,10 +34,17 @@ func ValidatePolicy(policy schedulerapi.Policy) error {
 		}
 	}
 
+	binders := 0
 	for _, extender := range policy.ExtenderConfigs {
 		if extender.Weight <= 0 {
 			validationErrors = append(validationErrors, fmt.Errorf("Priority for extender %s should have a positive weight applied to it", extender.URLPrefix))
 		}
+		if extender.BindVerb != "" {
+			binders++
+		}
+	}
+	if binders > 1 {
+		validationErrors = append(validationErrors, fmt.Errorf("Only one extender can implement bind, found %v", binders))
 	}
 	return utilerrors.NewAggregate(validationErrors)
 }

plugin/pkg/scheduler/api/validation/validation_test.go

@@ -72,3 +72,15 @@ func TestValidateExtenderWithNegativeWeight(t *testing.T) {
 		t.Errorf("Expected error about priority weight for extender not being positive")
 	}
 }
+
+func TestValidateMultipleExtendersWithBind(t *testing.T) {
+	extenderPolicy := api.Policy{
+		ExtenderConfigs: []api.ExtenderConfig{
+			{URLPrefix: "http://127.0.0.1:8081/extender", BindVerb: "bind"},
+			{URLPrefix: "http://127.0.0.1:8082/extender", BindVerb: "bind"},
+		},
+	}
+	if ValidatePolicy(extenderPolicy) == nil {
+		t.Errorf("Expected failure when multiple extenders with bind")
+	}
+}

plugin/pkg/scheduler/core/extender.go

@@ -41,6 +41,7 @@ type HTTPExtender struct {
 	extenderURL      string
 	filterVerb       string
 	prioritizeVerb   string
+	bindVerb         string
 	weight           int
 	client           *http.Client
 	nodeCacheCapable bool
@@ -86,6 +87,7 @@ func NewHTTPExtender(config *schedulerapi.ExtenderConfig) (algorithm.SchedulerEx
 		extenderURL:      config.URLPrefix,
 		filterVerb:       config.FilterVerb,
 		prioritizeVerb:   config.PrioritizeVerb,
+		bindVerb:         config.BindVerb,
 		weight:           config.Weight,
 		client:           client,
 		nodeCacheCapable: config.NodeCacheCapable,
@@ -193,6 +195,33 @@ func (h *HTTPExtender) Prioritize(pod *v1.Pod, nodes []*v1.Node) (*schedulerapi.
 	return &result, h.weight, nil
 }
 
+// Bind delegates the action of binding a pod to a node to the extender.
+func (h *HTTPExtender) Bind(binding *v1.Binding) error {
+	var result schedulerapi.ExtenderBindingResult
+	if !h.IsBinder() {
+		// This shouldn't happen as this extender wouldn't have become a Binder.
+		return fmt.Errorf("Unexpected empty bindVerb in extender")
+	}
+	req := &schedulerapi.ExtenderBindingArgs{
+		PodName:      binding.Name,
+		PodNamespace: binding.Namespace,
+		PodUID:       binding.UID,
+		Node:         binding.Target.Name,
+	}
+	if err := h.send(h.bindVerb, &req, &result); err != nil {
+		return err
+	}
+	if result.Error != "" {
+		return fmt.Errorf(result.Error)
+	}
+	return nil
+}
+
+// IsBinder returns whether this extender is configured for the Bind method.
+func (h *HTTPExtender) IsBinder() bool {
+	return h.bindVerb != ""
+}
+
 // Helper function to send messages to the extender
 func (h *HTTPExtender) send(action string, args interface{}, result interface{}) error {
 	out, err := json.Marshal(args)
@@ -214,6 +243,10 @@ func (h *HTTPExtender) send(action string, args interface{}, result interface{})
 		return err
 	}
 
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("Failed %v with extender at URL %v, code %v", action, h.extenderURL, resp.StatusCode)
+	}
+
 	defer resp.Body.Close()
 	body, err := ioutil.ReadAll(resp.Body)
 	if err != nil {

plugin/pkg/scheduler/core/extender_test.go

@@ -109,6 +109,7 @@ type FakeExtender struct {
 	prioritizers     []priorityConfig
 	weight           int
 	nodeCacheCapable bool
+	filteredNodes    []*v1.Node
 }
 
 func (f *FakeExtender) Filter(pod *v1.Pod, nodes []*v1.Node, nodeNameToInfo map[string]*schedulercache.NodeInfo) ([]*v1.Node, schedulerapi.FailedNodesMap, error) {
@@ -133,6 +134,7 @@ func (f *FakeExtender) Filter(pod *v1.Pod, nodes []*v1.Node, nodeNameToInfo map[
 		}
 	}
 
+	f.filteredNodes = filtered
 	if f.nodeCacheCapable {
 		return filtered, failedNodesMap, nil
 	}
@@ -162,6 +164,25 @@ func (f *FakeExtender) Prioritize(pod *v1.Pod, nodes []*v1.Node) (*schedulerapi.
 	return &result, f.weight, nil
 }
 
+func (f *FakeExtender) Bind(binding *v1.Binding) error {
+	if len(f.filteredNodes) != 0 {
+		for _, node := range f.filteredNodes {
+			if node.Name == binding.Target.Name {
+				f.filteredNodes = nil
+				return nil
+			}
+		}
+		err := fmt.Errorf("Node %v not in filtered nodes %v", binding.Target.Name, f.filteredNodes)
+		f.filteredNodes = nil
+		return err
+	}
+	return nil
+}
+
+func (f *FakeExtender) IsBinder() bool {
+	return true
+}
+
 func TestGenericSchedulerWithExtenders(t *testing.T) {
 	tests := []struct {
 		name                 string

plugin/pkg/scheduler/factory/factory.go

@@ -386,6 +386,16 @@ func (f *ConfigFactory) CreateFromConfig(policy schedulerapi.Policy) (*scheduler
 	return f.CreateFromKeys(predicateKeys, priorityKeys, extenders)
 }
 
+// getBinder returns an extender that supports bind or a default binder.
+func (f *ConfigFactory) getBinder(extenders []algorithm.SchedulerExtender) scheduler.Binder {
+	for i := range extenders {
+		if extenders[i].IsBinder() {
+			return extenders[i]
+		}
+	}
+	return &binder{f.client}
+}
+
 // Creates a scheduler from a set of registered fit predicate keys and priority keys.
 func (f *ConfigFactory) CreateFromKeys(predicateKeys, priorityKeys sets.String, extenders []algorithm.SchedulerExtender) (*scheduler.Config, error) {
 	glog.V(2).Infof("Creating scheduler with fit predicates '%v' and priority functions '%v", predicateKeys, priorityKeys)
@@ -422,7 +432,7 @@ func (f *ConfigFactory) CreateFromKeys(predicateKeys, priorityKeys sets.String,
 		// The scheduler only needs to consider schedulable nodes.
 		NodeLister:          &nodePredicateLister{f.nodeLister},
 		Algorithm:           algo,
-		Binder:              &binder{f.client},
+		Binder:              f.getBinder(extenders),
 		PodConditionUpdater: &podConditionUpdater{f.client},
 		WaitForCacheSync: func() bool {
 			return cache.WaitForCacheSync(f.StopEverything, f.scheduledPodsHasSynced)

plugin/pkg/scheduler/scheduler.go

@@ -271,7 +271,7 @@ func (sched *Scheduler) scheduleOne() {
 	// bind the pod to its host asynchronously (we can do this b/c of the assumption step above).
 	go func() {
 		err := sched.bind(pod, &v1.Binding{
-			ObjectMeta: metav1.ObjectMeta{Namespace: pod.Namespace, Name: pod.Name},
+			ObjectMeta: metav1.ObjectMeta{Namespace: pod.Namespace, Name: pod.Name, UID: pod.UID},
 			Target: v1.ObjectReference{
 				Kind: "Node",
 				Name: suggestedHost,