Rename NoSwap to LimitedSwap as workloads may still swap

Also made the options a kubelet type, address API review feedback

pkg/kubelet/apis/config/types.go

@@ -326,7 +326,7 @@ type KubeletConfiguration struct {
 	FeatureGates map[string]bool
 	// Tells the Kubelet to fail to start if swap is enabled on the node.
 	FailSwapOn bool
-	// Configure swap memory available to container workloads.
+	// memorySwap configures swap memory available to container workloads.
 	// +featureGate=NodeSwapEnabled
 	// +optional
 	MemorySwap MemorySwapConfiguration
@@ -574,8 +574,10 @@ type MemoryReservation struct {
 }
 
 type MemorySwapConfiguration struct {
-	// Configure swap memory available to container workloads. May be one of
+	// swapBehavior configures swap memory available to container workloads. May be one of
-	// "", "NoSwap": workloads cannot use swap
+	// "", "LimitedSwap": workload combined memory and swap usage cannot exceed pod memory limit
 	// "UnlimitedSwap": workloads can use unlimited swap, up to the allocatable limit.
+	// +featureGate=NodeSwapEnabled
+	// +optional
 	SwapBehavior string
 }

pkg/kubelet/apis/config/validation/validation.go

@@ -156,8 +156,8 @@ func ValidateKubeletConfiguration(kc *kubeletconfig.KubeletConfiguration) error
 		allErrors = append(allErrors, fmt.Errorf("invalid configuration: Specifying ShutdownGracePeriod or ShutdownGracePeriodCriticalPods requires feature gate GracefulNodeShutdown"))
 	}
 	if localFeatureGate.Enabled(features.NodeSwapEnabled) {
-		if kc.MemorySwap.SwapBehavior != "" && kc.MemorySwap.SwapBehavior != "NoSwap" && kc.MemorySwap.SwapBehavior != "UnlimitedSwap" {
+		if kc.MemorySwap.SwapBehavior != "" && kc.MemorySwap.SwapBehavior != kubetypes.LimitedSwap && kc.MemorySwap.SwapBehavior != kubetypes.UnlimitedSwap {
-			allErrors = append(allErrors, fmt.Errorf("invalid configuration: MemorySwap.SwapBehavior %v must be one of: NoSwap, UnlimitedSwap", kc.MemorySwap.SwapBehavior))
+			allErrors = append(allErrors, fmt.Errorf("invalid configuration: MemorySwap.SwapBehavior %v must be one of: LimitedSwap, UnlimitedSwap", kc.MemorySwap.SwapBehavior))
 		}
 	}
 

pkg/kubelet/apis/config/validation/validation_test.go

@@ -24,6 +24,7 @@ import (
 	utilerrors "k8s.io/apimachinery/pkg/util/errors"
 	componentbaseconfig "k8s.io/component-base/config"
 	kubeletconfig "k8s.io/kubernetes/pkg/kubelet/apis/config"
+	kubetypes "k8s.io/kubernetes/pkg/kubelet/types"
 )
 
 func TestValidateKubeletConfiguration(t *testing.T) {
@@ -145,7 +146,7 @@ func TestValidateKubeletConfiguration(t *testing.T) {
 		TopologyManagerPolicy:           kubeletconfig.NoneTopologyManagerPolicy,
 		ShutdownGracePeriod:             metav1.Duration{Duration: 10 * time.Minute},
 		ShutdownGracePeriodCriticalPods: metav1.Duration{Duration: 0},
-		MemorySwap:                      kubeletconfig.MemorySwapConfiguration{SwapBehavior: "UnlimitedSwap"},
+		MemorySwap:                      kubeletconfig.MemorySwapConfiguration{SwapBehavior: kubetypes.UnlimitedSwap},
 		FeatureGates: map[string]bool{
 			"CustomCPUCFSQuotaPeriod": true,
 			"GracefulNodeShutdown":    true,

pkg/kubelet/kuberuntime/kuberuntime_container_linux.go

@@ -30,6 +30,7 @@ import (
 	kubefeatures "k8s.io/kubernetes/pkg/features"
 	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
 	"k8s.io/kubernetes/pkg/kubelet/qos"
+	kubelettypes "k8s.io/kubernetes/pkg/kubelet/types"
 )
 
 // applyPlatformSpecificContainerConfig applies platform specific configurations to runtimeapi.ContainerConfig.
@@ -93,11 +94,12 @@ func (m *kubeGenericRuntimeManager) generateLinuxContainerConfig(container *v1.C
 		// NOTE(ehashman): Behaviour is defined in the opencontainers runtime spec:
 		// https://github.com/opencontainers/runtime-spec/blob/1c3f411f041711bbeecf35ff7e93461ea6789220/config-linux.md#memory
 		switch m.memorySwapBehavior {
-		case "UnlimitedSwap":
+		case kubelettypes.UnlimitedSwap:
 			// -1 = unlimited swap
 			lc.Resources.MemorySwapLimitInBytes = -1
 		default:
-			// memorySwapLimit = total permitted memory+swap; if equal to memory limit, => 0 swap
+			// memorySwapLimit = total permitted memory+swap; if equal to memory limit, => 0 swap above memory limit
+			// Some swapping is still possible.
 			// Note that if memory limit is 0, memory swap limit is ignored.
 			lc.Resources.MemorySwapLimitInBytes = lc.Resources.MemoryLimitInBytes
 		}

pkg/kubelet/kuberuntime/kuberuntime_container_linux_test.go

@@ -33,6 +33,7 @@ import (
 	runtimeapi "k8s.io/cri-api/pkg/apis/runtime/v1alpha2"
 	"k8s.io/kubernetes/pkg/features"
 	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
+	kubelettypes "k8s.io/kubernetes/pkg/kubelet/types"
 )
 
 func makeExpectedConfig(m *kubeGenericRuntimeManager, pod *v1.Pod, containerIndex int) *runtimeapi.ContainerConfig {
@@ -417,8 +418,8 @@ func TestGenerateLinuxContainerConfigSwap(t *testing.T) {
 		},
 		{
 			// Note: behaviour will be the same as previous two cases
-			name:        "config set to NoSwap, memory limit set",
+			name:        "config set to LimitedSwap, memory limit set",
-			swapSetting: "NoSwap",
+			swapSetting: kubelettypes.LimitedSwap,
 			pod: &v1.Pod{
 				Spec: v1.PodSpec{
 					Containers: []v1.Container{{
@@ -438,7 +439,7 @@ func TestGenerateLinuxContainerConfigSwap(t *testing.T) {
 		},
 		{
 			name:        "UnlimitedSwap enabled",
-			swapSetting: "UnlimitedSwap",
+			swapSetting: kubelettypes.UnlimitedSwap,
 			pod: &v1.Pod{
 				Spec: v1.PodSpec{
 					Containers: []v1.Container{

pkg/kubelet/types/constants.go

@@ -38,3 +38,9 @@ const (
 	KubeReservedEnforcementKey    = "kube-reserved"
 	NodeAllocatableNoneKey        = "none"
 )
+
+// SwapBehavior types
+const (
+	LimitedSwap   = "LimitedSwap"
+	UnlimitedSwap = "UnlimitedSwap"
+)

staging/src/k8s.io/kubelet/config/v1beta1/types.go

@@ -752,7 +752,7 @@ type KubeletConfiguration struct {
 	// Default: true
 	// +optional
 	FailSwapOn *bool `json:"failSwapOn,omitempty"`
-	// Configure swap memory available to container workloads.
+	// memorySwap configures swap memory available to container workloads.
 	// +featureGate=NodeSwapEnabled
 	// +optional
 	MemorySwap MemorySwapConfiguration `json:"memorySwap,omitempty"`
@@ -1040,9 +1040,11 @@ type MemoryReservation struct {
 	Limits   v1.ResourceList `json:"limits"`
 }
 
-// Configure swap memory available to container workloads. May be one of
-// "", "NoSwap": workloads cannot use swap
-// "UnlimitedSwap": workloads can use unlimited swap, up to the allocatable limit.
 type MemorySwapConfiguration struct {
+	// swapBehavior configures swap memory available to container workloads. May be one of
+	// "", "LimitedSwap": workload combined memory and swap usage cannot exceed pod memory limit
+	// "UnlimitedSwap": workloads can use unlimited swap, up to the allocatable limit.
+	// +featureGate=NodeSwapEnabled
+	// +optional
 	SwapBehavior string `json:"swapBehavior,omitempty"`
 }