Merge pull request #120534 from pohly/dra-scheduler-ssa-as-fallback

dra scheduler: fall back to SSA for PodSchedulingContext updates

pkg/scheduler/framework/plugins/dynamicresources/dynamicresources.go

@@ -33,6 +33,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/util/sets"
+	resourcev1alpha2apply "k8s.io/client-go/applyconfigurations/resource/v1alpha2"
 	"k8s.io/client-go/kubernetes"
 	resourcev1alpha2listers "k8s.io/client-go/listers/resource/v1alpha2"
 	"k8s.io/component-helpers/scheduling/corev1/nodeaffinity"
@@ -187,6 +188,41 @@ func (p *podSchedulingState) publish(ctx context.Context, pod *v1.Pod, clientset
 			logger.V(5).Info("Updating PodSchedulingContext", "podSchedulingCtx", klog.KObj(schedulingCtx))
 		}
 		_, err = clientset.ResourceV1alpha2().PodSchedulingContexts(schedulingCtx.Namespace).Update(ctx, schedulingCtx, metav1.UpdateOptions{})
+		if apierrors.IsConflict(err) {
+			// We don't use SSA by default for performance reasons
+			// (https://github.com/kubernetes/kubernetes/issues/113700#issuecomment-1698563918)
+			// because most of the time an Update doesn't encounter
+			// a conflict and is faster.
+			//
+			// We could return an error here and rely on
+			// backoff+retry, but scheduling attempts are expensive
+			// and the backoff delay would cause a (small)
+			// slowdown. Therefore we fall back to SSA here if needed.
+			//
+			// Using SSA instead of Get+Update has the advantage that
+			// there is no delay for the Get. SSA is safe because only
+			// the scheduler updates these fields.
+			spec := resourcev1alpha2apply.PodSchedulingContextSpec()
+			spec.SelectedNode = p.selectedNode
+			if p.potentialNodes != nil {
+				spec.PotentialNodes = *p.potentialNodes
+			} else {
+				// Unchanged. Has to be set because the object that we send
+				// must represent the "fully specified intent". Not sending
+				// the list would clear it.
+				spec.PotentialNodes = p.schedulingCtx.Spec.PotentialNodes
+			}
+			schedulingCtxApply := resourcev1alpha2apply.PodSchedulingContext(pod.Name, pod.Namespace).WithSpec(spec)
+
+			if loggerV := logger.V(6); loggerV.Enabled() {
+				// At a high enough log level, dump the entire object.
+				loggerV.Info("Patching PodSchedulingContext", "podSchedulingCtx", klog.KObj(pod), "podSchedulingCtxApply", klog.Format(schedulingCtxApply))
+			} else {
+				logger.V(5).Info("Patching PodSchedulingContext", "podSchedulingCtx", klog.KObj(pod))
+			}
+			_, err = clientset.ResourceV1alpha2().PodSchedulingContexts(pod.Namespace).Apply(ctx, schedulingCtxApply, metav1.ApplyOptions{FieldManager: "kube-scheduler", Force: true})
+		}
+
 	} else {
 		// Create it.
 		schedulingCtx := &resourcev1alpha2.PodSchedulingContext{

test/integration/scheduler/scheduler_test.go

@@ -21,24 +21,33 @@ package scheduler
 import (
 	"context"
 	"fmt"
+	"net/http"
+	"strings"
+	"sync/atomic"
 	"testing"
 	"time"
 
 	"github.com/google/go-cmp/cmp"
 	v1 "k8s.io/api/core/v1"
+	resourcev1alpha2 "k8s.io/api/resource/v1alpha2"
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/api/resource"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/apimachinery/pkg/watch"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	clientset "k8s.io/client-go/kubernetes"
 	corelisters "k8s.io/client-go/listers/core/v1"
 	"k8s.io/client-go/tools/cache"
+	featuregatetesting "k8s.io/component-base/featuregate/testing"
 	configv1 "k8s.io/kube-scheduler/config/v1"
+	"k8s.io/kubernetes/pkg/features"
 	"k8s.io/kubernetes/pkg/scheduler"
 	configtesting "k8s.io/kubernetes/pkg/scheduler/apis/config/testing"
 	st "k8s.io/kubernetes/pkg/scheduler/testing"
 	testutils "k8s.io/kubernetes/test/integration/util"
+	"k8s.io/kubernetes/test/utils/format"
 	"k8s.io/utils/pointer"
 )
 
@@ -611,3 +620,131 @@ func TestNodeEvents(t *testing.T) {
 	}
 
 }
+
+// TestPodSchedulingContextSSA checks that the dynamicresources plugin falls
+// back to SSA successfully when the normal Update call encountered
+// a conflict.
+//
+// This is an integration test because:
+//   - Unit testing does not cover RBAC rules.
+//   - Triggering this particular race is harder in E2E testing
+//     and harder to verify (needs apiserver metrics and there's
+//     no standard API for those).
+func TestPodSchedulingContextSSA(t *testing.T) {
+	defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.DynamicResourceAllocation, true)()
+
+	testCtx := testutils.InitTestAPIServer(t, "podschedulingcontext-ssa", nil)
+	testCtx.DisableEventSink = true
+	testCtx = testutils.InitTestSchedulerWithOptions(t, testCtx, 0)
+	testutils.SyncSchedulerInformerFactory(testCtx)
+	go testCtx.Scheduler.Run(testCtx.SchedulerCtx)
+
+	// Set up enough objects that the scheduler will start trying to
+	// schedule the pod and create the PodSchedulingContext.
+	nodeRes := map[v1.ResourceName]string{
+		v1.ResourcePods:   "32",
+		v1.ResourceCPU:    "30m",
+		v1.ResourceMemory: "30",
+	}
+	for _, name := range []string{"node-a", "node-b"} {
+		if _, err := testutils.CreateNode(testCtx.ClientSet, st.MakeNode().Name(name).Capacity(nodeRes).Obj()); err != nil {
+			t.Fatalf("Failed to create node: %v", err)
+		}
+	}
+
+	defer func() {
+		if err := testCtx.ClientSet.ResourceV1alpha2().ResourceClasses().DeleteCollection(testCtx.Ctx, metav1.DeleteOptions{}, metav1.ListOptions{}); err != nil {
+			t.Errorf("Unexpected error deleting ResourceClasses: %v", err)
+		}
+	}()
+	class := &resourcev1alpha2.ResourceClass{
+		ObjectMeta: metav1.ObjectMeta{
+			Name: "my-class",
+		},
+		DriverName: "does-not-matter",
+	}
+	if _, err := testCtx.ClientSet.ResourceV1alpha2().ResourceClasses().Create(testCtx.Ctx, class, metav1.CreateOptions{}); err != nil {
+		t.Fatalf("Failed to create class: %v", err)
+	}
+
+	claim := &resourcev1alpha2.ResourceClaim{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      "my-claim",
+			Namespace: testCtx.NS.Name,
+		},
+		Spec: resourcev1alpha2.ResourceClaimSpec{
+			ResourceClassName: class.Name,
+		},
+	}
+	if _, err := testCtx.ClientSet.ResourceV1alpha2().ResourceClaims(claim.Namespace).Create(testCtx.Ctx, claim, metav1.CreateOptions{}); err != nil {
+		t.Fatalf("Failed to create claim: %v", err)
+	}
+
+	podConf := testutils.PausePodConfig{
+		Name:      "testpod",
+		Namespace: testCtx.NS.Name,
+	}
+	pod := testutils.InitPausePod(&podConf)
+	podClaimName := "myclaim"
+	pod.Spec.Containers[0].Resources.Claims = []v1.ResourceClaim{{Name: podClaimName}}
+	pod.Spec.ResourceClaims = []v1.PodResourceClaim{{Name: podClaimName, Source: v1.ClaimSource{ResourceClaimName: &claim.Name}}}
+	if _, err := testCtx.ClientSet.CoreV1().Pods(pod.Namespace).Create(testCtx.Ctx, pod, metav1.CreateOptions{}); err != nil {
+		t.Fatalf("Failed to create pod: %v", err)
+	}
+
+	// Check that the PodSchedulingContext exists and has a selected node.
+	var schedulingCtx *resourcev1alpha2.PodSchedulingContext
+	if err := wait.PollUntilContextTimeout(testCtx.Ctx, 10*time.Microsecond, 30*time.Second, true,
+		func(context.Context) (bool, error) {
+			var err error
+			schedulingCtx, err = testCtx.ClientSet.ResourceV1alpha2().PodSchedulingContexts(pod.Namespace).Get(testCtx.Ctx, pod.Name, metav1.GetOptions{})
+			if apierrors.IsNotFound(err) {
+				return false, nil
+			}
+			if err == nil && schedulingCtx.Spec.SelectedNode != "" {
+				return true, nil
+			}
+			return false, err
+		}); err != nil {
+		t.Fatalf("Failed while waiting for PodSchedulingContext with selected node: %v\nLast PodSchedulingContext:\n%s", err, format.Object(schedulingCtx, 1))
+	}
+
+	// Force the plugin to use SSA.
+	var podSchedulingContextPatchCounter atomic.Int64
+	roundTrip := testutils.RoundTripWrapper(func(transport http.RoundTripper, req *http.Request) (*http.Response, error) {
+		if strings.HasPrefix(req.URL.Path, "/apis/resource.k8s.io/") &&
+			strings.HasSuffix(req.URL.Path, "/podschedulingcontexts/"+pod.Name) {
+			switch req.Method {
+			case http.MethodPut, http.MethodPost:
+				return &http.Response{
+					Status:     fmt.Sprintf("%d %s", http.StatusConflict, metav1.StatusReasonConflict),
+					StatusCode: http.StatusConflict,
+				}, nil
+			case http.MethodPatch:
+				podSchedulingContextPatchCounter.Add(1)
+			}
+		}
+		return transport.RoundTrip(req)
+	})
+	testCtx.RoundTrip.Store(&roundTrip)
+
+	// Now force the scheduler to update the PodSchedulingContext by setting UnsuitableNodes so that
+	// the selected node is not suitable.
+	schedulingCtx.Status.ResourceClaims = []resourcev1alpha2.ResourceClaimSchedulingStatus{{
+		Name:            podClaimName,
+		UnsuitableNodes: []string{schedulingCtx.Spec.SelectedNode},
+	}}
+
+	if _, err := testCtx.ClientSet.ResourceV1alpha2().PodSchedulingContexts(pod.Namespace).UpdateStatus(testCtx.Ctx, schedulingCtx, metav1.UpdateOptions{}); err != nil {
+		t.Fatalf("Unexpected PodSchedulingContext status update error: %v", err)
+	}
+
+	// We know that the scheduler has to use SSA because above we inject a conflict
+	// error whenever it tries to use a plain update. We just need to wait for it...
+	if err := wait.PollUntilContextTimeout(testCtx.Ctx, 10*time.Microsecond, time.Minute, true,
+		func(context.Context) (bool, error) {
+			return podSchedulingContextPatchCounter.Load() > 0, nil
+		}); err != nil {
+		t.Fatalf("Failed while waiting for PodSchedulingContext Patch: %v", err)
+	}
+}

test/integration/util/util.go

@@ -21,17 +21,21 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"net/http"
+	"sync/atomic"
 	"testing"
 	"time"
 
 	v1 "k8s.io/api/core/v1"
 	policy "k8s.io/api/policy/v1"
+	resourcev1alpha2 "k8s.io/api/resource/v1alpha2"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/uuid"
 	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/apiserver/pkg/admission"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	cacheddiscovery "k8s.io/client-go/discovery/cached/memory"
 	"k8s.io/client-go/dynamic"
 	"k8s.io/client-go/dynamic/dynamicinformer"
@@ -45,6 +49,7 @@ import (
 	"k8s.io/client-go/scale"
 	"k8s.io/client-go/tools/cache"
 	"k8s.io/client-go/tools/events"
+	cliflag "k8s.io/component-base/cli/flag"
 	pvutil "k8s.io/component-helpers/storage/volume"
 	"k8s.io/controller-manager/pkg/informerfactory"
 	"k8s.io/klog/v2"
@@ -56,6 +61,7 @@ import (
 	"k8s.io/kubernetes/pkg/controller/namespace"
 	"k8s.io/kubernetes/pkg/controller/resourceclaim"
 	"k8s.io/kubernetes/pkg/controlplane"
+	"k8s.io/kubernetes/pkg/features"
 	"k8s.io/kubernetes/pkg/scheduler"
 	kubeschedulerconfig "k8s.io/kubernetes/pkg/scheduler/apis/config"
 	configtesting "k8s.io/kubernetes/pkg/scheduler/apis/config/testing"
@@ -239,8 +245,15 @@ func CreateNamespaceController(ctx context.Context, tb testing.TB, restConfig re
 	}
 }
 
-// TestContext store necessary context info
+// TestContext store necessary context info.
+// It also contains some optional parameters for InitTestScheduler.
 type TestContext struct {
+	// DisableEventSink, if set to true before calling InitTestScheduler,
+	// will skip the eventBroadcaster.StartRecordingToSink and thus
+	// some extra goroutines which are tricky to get rid of after
+	// a test.
+	DisableEventSink bool
+
 	NS                 *v1.Namespace
 	ClientSet          clientset.Interface
 	KubeConfig         *restclient.Config
@@ -257,8 +270,29 @@ type TestContext struct {
 	// SchedulerCloseFn will tear down the resources in creating scheduler,
 	// including the scheduler itself.
 	SchedulerCloseFn framework.TearDownFunc
+
+	// RoundTrip, if set, will be called for every HTTP request going to the apiserver.
+	// It can be used for error injection.
+	RoundTrip atomic.Pointer[RoundTripWrapper]
 }
 
+type RoundTripWrapper func(http.RoundTripper, *http.Request) (*http.Response, error)
+
+type roundTripWrapper struct {
+	tc        *TestContext
+	transport http.RoundTripper
+}
+
+func (r roundTripWrapper) RoundTrip(req *http.Request) (*http.Response, error) {
+	wrapper := r.tc.RoundTrip.Load()
+	if wrapper != nil {
+		return (*wrapper)(r.transport, req)
+	}
+	return r.transport.RoundTrip(req)
+}
+
+var _ http.RoundTripper = roundTripWrapper{}
+
 // CleanupNodes cleans all nodes which were created during integration test
 func CleanupNodes(cs clientset.Interface, t *testing.T) {
 	err := cs.CoreV1().Nodes().DeleteCollection(context.TODO(), *metav1.NewDeleteOptions(0), metav1.ListOptions{})
@@ -468,11 +502,16 @@ func UpdateNodeStatus(cs clientset.Interface, node *v1.Node) error {
 func InitTestAPIServer(t *testing.T, nsPrefix string, admission admission.Interface) *TestContext {
 	_, ctx := ktesting.NewTestContext(t)
 	ctx, cancel := context.WithCancel(ctx)
-	testCtx := TestContext{Ctx: ctx}
+	testCtx := &TestContext{Ctx: ctx}
 
 	testCtx.ClientSet, testCtx.KubeConfig, testCtx.CloseFn = framework.StartTestServer(ctx, t, framework.TestServerSetup{
 		ModifyServerRunOptions: func(options *options.ServerRunOptions) {
 			options.Admission.GenericAdmission.DisablePlugins = []string{"ServiceAccount", "TaintNodesByCondition", "Priority", "StorageObjectInUseProtection"}
+			if utilfeature.DefaultFeatureGate.Enabled(features.DynamicResourceAllocation) {
+				options.APIEnablement.RuntimeConfig = cliflag.ConfigurationMap{
+					resourcev1alpha2.SchemeGroupVersion.String(): "true",
+				}
+			}
 		},
 		ModifyServerConfig: func(config *controlplane.Config) {
 			if admission != nil {
@@ -481,6 +520,16 @@ func InitTestAPIServer(t *testing.T, nsPrefix string, admission admission.Interf
 		},
 	})
 
+	// Support wrapping HTTP requests.
+	testCtx.KubeConfig.Wrap(func(transport http.RoundTripper) http.RoundTripper {
+		return roundTripWrapper{tc: testCtx, transport: transport}
+	})
+	var err error
+	testCtx.ClientSet, err = clientset.NewForConfig(testCtx.KubeConfig)
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	oldCloseFn := testCtx.CloseFn
 	testCtx.CloseFn = func() {
 		cancel()
@@ -494,10 +543,10 @@ func InitTestAPIServer(t *testing.T, nsPrefix string, admission admission.Interf
 	}
 
 	t.Cleanup(func() {
-		CleanupTest(t, &testCtx)
+		CleanupTest(t, testCtx)
 	})
 
-	return &testCtx
+	return testCtx
 }
 
 // WaitForSchedulerCacheCleanup waits for cleanup of scheduler's cache to complete
@@ -560,7 +609,9 @@ func InitTestSchedulerWithOptions(
 		t.Fatalf("Couldn't create scheduler: %v", err)
 	}
 
-	eventBroadcaster.StartRecordingToSink(ctx.Done())
+	if !testCtx.DisableEventSink {
+		eventBroadcaster.StartRecordingToSink(ctx.Done())
+	}
 
 	oldCloseFn := testCtx.CloseFn
 	testCtx.CloseFn = func() {