Add Un-reserve extension point for the scheduling framework

pkg/scheduler/framework/v1alpha1/framework.go

@@ -33,6 +33,7 @@ type framework struct {
 	plugins          map[string]Plugin // a map of initialized plugins. Plugin name:plugin instance.
 	reservePlugins   []ReservePlugin
 	prebindPlugins   []PrebindPlugin
+	unreservePlugins []UnreservePlugin
 }
 
 var _ = Framework(&framework{})
@@ -64,6 +65,9 @@ func NewFramework(r Registry, _ *runtime.Unknown) (Framework, error) {
 		if pp, ok := p.(PrebindPlugin); ok {
 			f.prebindPlugins = append(f.prebindPlugins, pp)
 		}
+		if up, ok := p.(UnreservePlugin); ok {
+			f.unreservePlugins = append(f.unreservePlugins, up)
+		}
 	}
 	return f, nil
 }
@@ -105,6 +109,14 @@ func (f *framework) RunReservePlugins(
 	return nil
 }
 
+// RunUnreservePlugins runs the set of configured unreserve plugins.
+func (f *framework) RunUnreservePlugins(
+	pc *PluginContext, pod *v1.Pod, nodeName string) {
+	for _, pl := range f.unreservePlugins {
+		pl.Unreserve(pc, pod, nodeName)
+	}
+}
+
 // NodeInfoSnapshot returns the latest NodeInfo snapshot. The snapshot
 // is taken at the beginning of a scheduling cycle and remains unchanged until a
 // pod finishes "Reserve". There is no guarantee that the information remains

pkg/scheduler/framework/v1alpha1/interface.go

@@ -113,6 +113,17 @@ type PrebindPlugin interface {
 	Prebind(pc *PluginContext, p *v1.Pod, nodeName string) *Status
 }
 
+// UnreservePlugin is an interface for Unreserve plugins. This is an informational
+// extension point. If a pod was reserved and then rejected in a later phase, then
+// un-reserve plugins will be notified. Un-reserve plugins should clean up state
+// associated with the reserved Pod.
+type UnreservePlugin interface {
+	Plugin
+	// Unreserve is called by the scheduling framework when a reserved pod was
+	// rejected in a later phase.
+	Unreserve(pc *PluginContext, p *v1.Pod, nodeName string)
+}
+
 // 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 {
@@ -128,6 +139,9 @@ type Framework interface {
 	// plugins returns an error, it does not continue running the remaining ones and
 	// returns the error. In such case, pod will not be scheduled.
 	RunReservePlugins(pc *PluginContext, pod *v1.Pod, nodeName string) *Status
+
+	// RunUnreservePlugins runs the set of configured unreserve plugins.
+	RunUnreservePlugins(pc *PluginContext, pod *v1.Pod, nodeName string)
 }
 
 // FrameworkHandle provides data and some tools that plugins can use. It is

pkg/scheduler/scheduler.go

@@ -515,6 +515,8 @@ func (sched *Scheduler) scheduleOne() {
 	if err != nil {
 		klog.Errorf("error assuming pod: %v", err)
 		metrics.PodScheduleErrors.Inc()
+		// trigger un-reserve plugins to clean up state associated with the reserved Pod
+		fwk.RunUnreservePlugins(pluginContext, assumedPod, scheduleResult.SuggestedHost)
 		return
 	}
 	// bind the pod to its host asynchronously (we can do this b/c of the assumption step above).
@@ -525,6 +527,8 @@ func (sched *Scheduler) scheduleOne() {
 			if err != nil {
 				klog.Errorf("error binding volumes: %v", err)
 				metrics.PodScheduleErrors.Inc()
+				// trigger un-reserve plugins to clean up state associated with the reserved Pod
+				fwk.RunUnreservePlugins(pluginContext, assumedPod, scheduleResult.SuggestedHost)
 				return
 			}
 		}
@@ -543,6 +547,8 @@ func (sched *Scheduler) scheduleOne() {
 				klog.Errorf("scheduler cache ForgetPod failed: %v", forgetErr)
 			}
 			sched.recordSchedulingFailure(assumedPod, prebindStatus.AsError(), reason, prebindStatus.Message())
+			// trigger un-reserve plugins to clean up state associated with the reserved Pod
+			fwk.RunUnreservePlugins(pluginContext, assumedPod, scheduleResult.SuggestedHost)
 			return
 		}
 
@@ -558,6 +564,8 @@ func (sched *Scheduler) scheduleOne() {
 		if err != nil {
 			klog.Errorf("error binding pod: %v", err)
 			metrics.PodScheduleErrors.Inc()
+			// trigger un-reserve plugins to clean up state associated with the reserved Pod
+			fwk.RunUnreservePlugins(pluginContext, assumedPod, scheduleResult.SuggestedHost)
 		} else {
 			klog.V(2).Infof("pod %v/%v is bound successfully on node %v, %d nodes evaluated, %d nodes were found feasible", assumedPod.Namespace, assumedPod.Name, scheduleResult.SuggestedHost, scheduleResult.EvaluatedNodes, scheduleResult.FeasibleNodes)
 			metrics.PodScheduleSuccesses.Inc()

test/integration/scheduler/framework_test.go

@@ -18,23 +18,24 @@ package scheduler
 
 import (
 	"fmt"
-	"k8s.io/apimachinery/pkg/runtime"
 	"testing"
 	"time"
 
 	"k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/wait"
 	framework "k8s.io/kubernetes/pkg/scheduler/framework/v1alpha1"
 )
 
 // TesterPlugin is common ancestor for a test plugin that allows injection of
 // failures and some other test functionalities.
 type TesterPlugin struct {
-	numReserveCalled int
-	numPrebindCalled int
-	failReserve      bool
-	failPrebind      bool
-	rejectPrebind    bool
+	numReserveCalled   int
+	numPrebindCalled   int
+	numUnreserveCalled int
+	failReserve        bool
+	failPrebind        bool
+	rejectPrebind      bool
 }
 
 type ReservePlugin struct {
@@ -45,19 +46,27 @@ type PrebindPlugin struct {
 	TesterPlugin
 }
 
+type UnreservePlugin struct {
+	TesterPlugin
+}
+
 const (
-	reservePluginName = "reserve-plugin"
-	prebindPluginName = "prebind-plugin"
+	reservePluginName   = "reserve-plugin"
+	prebindPluginName   = "prebind-plugin"
+	unreservePluginName = "unreserve-plugin"
 )
 
 var _ = framework.ReservePlugin(&ReservePlugin{})
 var _ = framework.PrebindPlugin(&PrebindPlugin{})
+var _ = framework.UnreservePlugin(&UnreservePlugin{})
 
 // Name returns name of the plugin.
 func (rp *ReservePlugin) Name() string {
 	return reservePluginName
 }
 
+var resPlugin = &ReservePlugin{}
+
 // Reserve is a test function that returns an error or nil, depending on the
 // value of "failReserve".
 func (rp *ReservePlugin) Reserve(pc *framework.PluginContext, pod *v1.Pod, nodeName string) *framework.Status {
@@ -68,14 +77,13 @@ func (rp *ReservePlugin) Reserve(pc *framework.PluginContext, pod *v1.Pod, nodeN
 	return nil
 }
 
-var resPlugin = &ReservePlugin{}
-var pbdPlugin = &PrebindPlugin{}
-
 // NewReservePlugin is the factory for reserve plugin.
 func NewReservePlugin(_ *runtime.Unknown, _ framework.FrameworkHandle) (framework.Plugin, error) {
 	return resPlugin, nil
 }
 
+var pbdPlugin = &PrebindPlugin{}
+
 // Name returns name of the plugin.
 func (pp *PrebindPlugin) Name() string {
 	return prebindPluginName
@@ -93,11 +101,39 @@ func (pp *PrebindPlugin) Prebind(pc *framework.PluginContext, pod *v1.Pod, nodeN
 	return nil
 }
 
+// reset used to reset numPrebindCalled.
+func (pp *PrebindPlugin) reset() {
+	pp.numPrebindCalled = 0
+}
+
 // NewPrebindPlugin is the factory for prebind plugin.
 func NewPrebindPlugin(_ *runtime.Unknown, _ framework.FrameworkHandle) (framework.Plugin, error) {
 	return pbdPlugin, nil
 }
 
+var unresPlugin = &UnreservePlugin{}
+
+// Name returns name of the plugin.
+func (up *UnreservePlugin) Name() string {
+	return unreservePluginName
+}
+
+// Unreserve is a test function that returns an error or nil, depending on the
+// value of "failUnreserve".
+func (up *UnreservePlugin) Unreserve(pc *framework.PluginContext, pod *v1.Pod, nodeName string) {
+	up.numUnreserveCalled++
+}
+
+// reset used to reset numUnreserveCalled.
+func (up *UnreservePlugin) reset() {
+	up.numUnreserveCalled = 0
+}
+
+// NewUnreservePlugin is the factory for unreserve plugin.
+func NewUnreservePlugin(_ *runtime.Unknown, _ framework.FrameworkHandle) (framework.Plugin, error) {
+	return unresPlugin, nil
+}
+
 // TestReservePlugin tests invocation of reserve plugins.
 func TestReservePlugin(t *testing.T) {
 	// Create a plugin registry for testing. Register only a reserve plugin.
@@ -216,3 +252,87 @@ func TestPrebindPlugin(t *testing.T) {
 		cleanupPods(cs, t, []*v1.Pod{pod})
 	}
 }
+
+// TestUnreservePlugin tests invocation of un-reserve plugin
+func TestUnreservePlugin(t *testing.T) {
+	// TODO: register more plugin which would trigger un-reserve plugin
+	registry := framework.Registry{
+		unreservePluginName: NewUnreservePlugin,
+		prebindPluginName:   NewPrebindPlugin,
+	}
+
+	// Create the master and the scheduler with the test plugin set.
+	context := initTestSchedulerWithOptions(t,
+		initTestMaster(t, "unreserve-plugin", nil),
+		false, nil, registry, 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 {
+		prebindFail   bool
+		prebindReject bool
+	}{
+		{
+			prebindFail:   false,
+			prebindReject: false,
+		},
+		{
+			prebindFail:   true,
+			prebindReject: false,
+		},
+		{
+			prebindFail:   false,
+			prebindReject: true,
+		},
+		{
+			prebindFail:   true,
+			prebindReject: true,
+		},
+	}
+
+	for i, test := range tests {
+		pbdPlugin.failPrebind = test.prebindFail
+		pbdPlugin.rejectPrebind = test.prebindReject
+
+		// 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.prebindFail {
+			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 unresPlugin.numUnreserveCalled == 0 || unresPlugin.numUnreserveCalled != pbdPlugin.numPrebindCalled {
+				t.Errorf("test #%v: Expected the unreserve plugin to be called %d times, was called %d times.", i, pbdPlugin.numPrebindCalled, unresPlugin.numUnreserveCalled)
+			}
+		} else {
+			if test.prebindReject {
+				if err = waitForPodUnschedulable(cs, pod); err != nil {
+					t.Errorf("test #%v: Didn't expected the pod to be scheduled. error: %v", i, err)
+				}
+				if unresPlugin.numUnreserveCalled == 0 || unresPlugin.numUnreserveCalled != pbdPlugin.numPrebindCalled {
+					t.Errorf("test #%v: Expected the unreserve plugin to be called %d times, was called %d times.", i, pbdPlugin.numPrebindCalled, unresPlugin.numUnreserveCalled)
+				}
+			} else {
+				if err = waitForPodToSchedule(cs, pod); err != nil {
+					t.Errorf("test #%v: Expected the pod to be scheduled. error: %v", i, err)
+				}
+				if unresPlugin.numUnreserveCalled > 0 {
+					t.Errorf("test #%v: Didn't expected the unreserve plugin to be called, was called %d times.", i, unresPlugin.numUnreserveCalled)
+				}
+			}
+		}
+		unresPlugin.reset()
+		pbdPlugin.reset()
+		cleanupPods(cs, t, []*v1.Pod{pod})
+	}
+}