From 0deef4610e8e62690136e98674d1bf0e8c85dffa Mon Sep 17 00:00:00 2001
From: Elana Hashman <ehashman@redhat.com>
Date: Wed, 16 Jun 2021 16:27:50 -0700
Subject: [PATCH] Set MemorySwapLimitInBytes for CRI when NodeSwapEnabled

---
 pkg/kubelet/kubelet.go                        |  1 +
 .../kuberuntime_container_linux.go            | 14 +++
 .../kuberuntime_container_linux_test.go       | 89 +++++++++++++++++++
 .../kuberuntime/kuberuntime_manager.go        |  5 ++
 4 files changed, 109 insertions(+)

diff --git a/pkg/kubelet/kubelet.go b/pkg/kubelet/kubelet.go
index ebf2fbf5e2f..43cad89dba0 100644
--- a/pkg/kubelet/kubelet.go
+++ b/pkg/kubelet/kubelet.go
@@ -652,6 +652,7 @@ func NewMainKubelet(kubeCfg *kubeletconfiginternal.KubeletConfiguration,
 		klet.containerLogManager,
 		klet.runtimeClassManager,
 		seccompDefault,
+		kubeCfg.MemorySwap.SwapBehavior,
 	)
 	if err != nil {
 		return nil, err
diff --git a/pkg/kubelet/kuberuntime/kuberuntime_container_linux.go b/pkg/kubelet/kuberuntime/kuberuntime_container_linux.go
index 85ad47772e8..c65d6b22946 100644
--- a/pkg/kubelet/kuberuntime/kuberuntime_container_linux.go
+++ b/pkg/kubelet/kuberuntime/kuberuntime_container_linux.go
@@ -89,6 +89,20 @@ func (m *kubeGenericRuntimeManager) generateLinuxContainerConfig(container *v1.C
 
 	lc.Resources.HugepageLimits = GetHugepageLimitsFromResources(container.Resources)
 
+	if utilfeature.DefaultFeatureGate.Enabled(kubefeatures.NodeSwapEnabled) {
+		// 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":
+			// -1 = unlimited swap
+			lc.Resources.MemorySwapLimitInBytes = -1
+		default:
+			// memorySwapLimit = total permitted memory+swap; if equal to memory limit, => 0 swap
+			// Note that if memory limit is 0, memory swap limit is ignored.
+			lc.Resources.MemorySwapLimitInBytes = lc.Resources.MemoryLimitInBytes
+		}
+	}
+
 	return lc
 }
 
diff --git a/pkg/kubelet/kuberuntime/kuberuntime_container_linux_test.go b/pkg/kubelet/kuberuntime/kuberuntime_container_linux_test.go
index 98203fef23e..2028c951453 100644
--- a/pkg/kubelet/kuberuntime/kuberuntime_container_linux_test.go
+++ b/pkg/kubelet/kuberuntime/kuberuntime_container_linux_test.go
@@ -367,3 +367,92 @@ func TestGenerateLinuxContainerConfigNamespaces(t *testing.T) {
 		})
 	}
 }
+
+func TestGenerateLinuxContainerConfigSwap(t *testing.T) {
+	defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.NodeSwapEnabled, true)()
+	_, _, m, err := createTestRuntimeManager()
+	if err != nil {
+		t.Fatalf("error creating test RuntimeManager: %v", err)
+	}
+	m.machineInfo.MemoryCapacity = 1000000
+	containerName := "test"
+
+	for _, tc := range []struct {
+		name        string
+		swapSetting string
+		pod         *v1.Pod
+		expected    int64
+	}{
+		{
+			name: "config unset, memory limit set",
+			// no swap setting
+			pod: &v1.Pod{
+				Spec: v1.PodSpec{
+					Containers: []v1.Container{{
+						Name: containerName,
+						Resources: v1.ResourceRequirements{
+							Limits: v1.ResourceList{
+								"memory": resource.MustParse("1000"),
+							},
+							Requests: v1.ResourceList{
+								"memory": resource.MustParse("1000"),
+							},
+						},
+					}},
+				},
+			},
+			expected: 1000,
+		},
+		{
+			name: "config unset, no memory limit",
+			// no swap setting
+			pod: &v1.Pod{
+				Spec: v1.PodSpec{
+					Containers: []v1.Container{
+						{Name: containerName},
+					},
+				},
+			},
+			expected: 0,
+		},
+		{
+			// Note: behaviour will be the same as previous two cases
+			name:        "config set to NoSwap, memory limit set",
+			swapSetting: "NoSwap",
+			pod: &v1.Pod{
+				Spec: v1.PodSpec{
+					Containers: []v1.Container{{
+						Name: containerName,
+						Resources: v1.ResourceRequirements{
+							Limits: v1.ResourceList{
+								"memory": resource.MustParse("1000"),
+							},
+							Requests: v1.ResourceList{
+								"memory": resource.MustParse("1000"),
+							},
+						},
+					}},
+				},
+			},
+			expected: 1000,
+		},
+		{
+			name:        "UnlimitedSwap enabled",
+			swapSetting: "UnlimitedSwap",
+			pod: &v1.Pod{
+				Spec: v1.PodSpec{
+					Containers: []v1.Container{
+						{Name: containerName},
+					},
+				},
+			},
+			expected: -1,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			m.memorySwapBehavior = tc.swapSetting
+			actual := m.generateLinuxContainerConfig(&tc.pod.Spec.Containers[0], tc.pod, nil, "", nil)
+			assert.Equal(t, tc.expected, actual.Resources.MemorySwapLimitInBytes, "memory swap config for %s", tc.name)
+		})
+	}
+}
diff --git a/pkg/kubelet/kuberuntime/kuberuntime_manager.go b/pkg/kubelet/kuberuntime/kuberuntime_manager.go
index c9bf6a847ee..87bf70b031e 100644
--- a/pkg/kubelet/kuberuntime/kuberuntime_manager.go
+++ b/pkg/kubelet/kuberuntime/kuberuntime_manager.go
@@ -144,6 +144,9 @@ type kubeGenericRuntimeManager struct {
 
 	// Use RuntimeDefault as the default seccomp profile for all workloads.
 	seccompDefault bool
+
+	// MemorySwapBehavior defines how swap is used
+	memorySwapBehavior string
 }
 
 // KubeGenericRuntime is a interface contains interfaces for container runtime and command.
@@ -186,6 +189,7 @@ func NewKubeGenericRuntimeManager(
 	logManager logs.ContainerLogManager,
 	runtimeClassManager *runtimeclass.Manager,
 	seccompDefault bool,
+	memorySwapBehavior string,
 ) (KubeGenericRuntime, error) {
 	kubeRuntimeManager := &kubeGenericRuntimeManager{
 		recorder:            recorder,
@@ -206,6 +210,7 @@ func NewKubeGenericRuntimeManager(
 		runtimeClassManager: runtimeClassManager,
 		logReduction:        logreduction.NewLogReduction(identicalErrorDelay),
 		seccompDefault:      seccompDefault,
+		memorySwapBehavior:  memorySwapBehavior,
 	}
 
 	typedVersion, err := kubeRuntimeManager.getTypedVersion()