Merge pull request kubernetes#47181 from dims/fail-on-swap-enabled

Automatic merge from submit-queue (batch tested with PRs 50119, 48366, 47181, 41611, 49547)

Fail on swap enabled and deprecate experimental-fail-swap-on flag

**What this PR does / why we need it**:

    * Deprecate the old experimental-fail-swap-on
    * Add a new flag fail-swap-on and set it to true

    Before this change, we would not fail when swap is on. With this
    change we fail for everyone when swap is on, unless they explicitly
    set --fail-swap-on to false.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #

Fixes kubernetes#34726

**Special notes for your reviewer**:

**Release note**:

```release-note
Kubelet will by default fail with swap enabled from now on. The experimental flag "--experimental-fail-swap-on" has been deprecated, please set the new "--fail-swap-on" flag to false if you wish to run with /proc/swaps on.
```

cmd/kubelet/app/options/options.go

@@ -144,8 +144,9 @@ func (f *KubeletFlags) AddFlags(fs *pflag.FlagSet) {
 
 // addFlags adds flags for a specific componentconfig.KubeletConfiguration to the specified FlagSet
 func (c *kubeletConfiguration) addFlags(fs *pflag.FlagSet) {
-	// TODO(#34726:1.8.0): Remove the opt-in for failing when swap is enabled.
-	fs.BoolVar(&c.ExperimentalFailSwapOn, "experimental-fail-swap-on", c.ExperimentalFailSwapOn, "Makes the Kubelet fail to start if swap is enabled on the node. This is a temporary opton to maintain legacy behavior, failing due to swap enabled will happen by default in v1.6.")
+	fs.BoolVar(&c.FailSwapOn, "fail-swap-on", true, "Makes the Kubelet fail to start if swap is enabled on the node. ")
+	fs.BoolVar(&c.FailSwapOn, "experimental-fail-swap-on", true, "DEPRECATED: please use --fail-swap-on instead.")
+	fs.MarkDeprecated("experimental-fail-swap-on", "This flag is deprecated and will be removed in future releases. please use --fail-swap-on instead.")
 
 	fs.StringVar(&c.PodManifestPath, "pod-manifest-path", c.PodManifestPath, "Path to to the directory containing pod manifest files to run, or the path to a single pod manifest file. Files starting with dots will be ignored.")
 	fs.DurationVar(&c.SyncFrequency.Duration, "sync-frequency", c.SyncFrequency.Duration, "Max period between synchronizing running containers and config")

cmd/kubelet/app/server.go

@@ -583,7 +583,7 @@ func run(s *options.KubeletServer, kubeDeps *kubelet.Dependencies) (err error) {
 				},
 				ExperimentalQOSReserved: *experimentalQOSReserved,
 			},
-			s.ExperimentalFailSwapOn,
+			s.FailSwapOn,
 			kubeDeps.Recorder)
 
 		if err != nil {

hack/verify-flags/known-flags.txt

@@ -271,6 +271,7 @@ external-hostname
 external-ip
 external-name
 extra-peer-dirs
+fail-swap-on
 failover-timeout
 failure-domains
 fake-clientset

pkg/apis/componentconfig/types.go

@@ -465,9 +465,8 @@ type KubeletConfiguration struct {
 	// featureGates is a string of comma-separated key=value pairs that describe feature
 	// gates for alpha/experimental features.
 	FeatureGates string
-	// TODO(#34726:1.8.0): Remove the opt-in for failing when swap is enabled.
 	// Tells the Kubelet to fail to start if swap is enabled on the node.
-	ExperimentalFailSwapOn bool
+	FailSwapOn bool
 	// This flag, if set, enables a check prior to mount operations to verify that the required components
 	// (binaries, etc.) to mount the volume are available on the underlying node. If the check is enabled
 	// and fails the mount operation fails.

pkg/apis/componentconfig/v1alpha1/types.go

@@ -530,9 +530,8 @@ type KubeletConfiguration struct {
 	// featureGates is a string of comma-separated key=value pairs that describe feature
 	// gates for alpha/experimental features.
 	FeatureGates string `json:"featureGates,omitempty"`
-	// TODO(#34726:1.8.0): Remove the opt-in for failing when swap is enabled.
 	// Tells the Kubelet to fail to start if swap is enabled on the node.
-	ExperimentalFailSwapOn bool `json:"experimentalFailSwapOn,omitempty"`
+	FailSwapOn bool `json:"failSwapOn,omitempty"`
 	// This flag, if set, enables a check prior to mount operations to verify that the required components
 	// (binaries, etc.) to mount the volume are available on the underlying node. If the check is enabled
 	// and fails the mount operation fails.

pkg/apis/componentconfig/v1alpha1/zz_generated.conversion.go

@@ -504,7 +504,7 @@ func autoConvert_v1alpha1_KubeletConfiguration_To_componentconfig_KubeletConfigu
 	}
 	out.AllowedUnsafeSysctls = *(*[]string)(unsafe.Pointer(&in.AllowedUnsafeSysctls))
 	out.FeatureGates = in.FeatureGates
-	out.ExperimentalFailSwapOn = in.ExperimentalFailSwapOn
+	out.FailSwapOn = in.FailSwapOn
 	out.ExperimentalCheckNodeCapabilitiesBeforeMount = in.ExperimentalCheckNodeCapabilitiesBeforeMount
 	out.KeepTerminatedPodVolumes = in.KeepTerminatedPodVolumes
 	out.SystemReserved = *(*componentconfig.ConfigurationMap)(unsafe.Pointer(&in.SystemReserved))
@@ -686,7 +686,7 @@ func autoConvert_componentconfig_KubeletConfiguration_To_v1alpha1_KubeletConfigu
 	}
 	out.AllowedUnsafeSysctls = *(*[]string)(unsafe.Pointer(&in.AllowedUnsafeSysctls))
 	out.FeatureGates = in.FeatureGates
-	out.ExperimentalFailSwapOn = in.ExperimentalFailSwapOn
+	out.FailSwapOn = in.FailSwapOn
 	out.ExperimentalCheckNodeCapabilitiesBeforeMount = in.ExperimentalCheckNodeCapabilitiesBeforeMount
 	out.KeepTerminatedPodVolumes = in.KeepTerminatedPodVolumes
 	out.SystemReserved = *(*map[string]string)(unsafe.Pointer(&in.SystemReserved))

pkg/kubelet/cm/container_manager_linux.go

@@ -204,18 +204,14 @@ func NewContainerManager(mountUtil mount.Interface, cadvisorInterface cadvisor.I
 		return nil, err
 	}
 
-	// TODO(#34726:1.8.0): Remove the opt-in for failing when swap is enabled.
-	//     Running with swap enabled should be considered an error, but in order to maintain legacy
-	//     behavior we have to require an opt-in to this error for a period of time.
-
-	// If there is more than one line (table headers) in /proc/swaps, swap is enabled and we should error out.
+	// Running with swap enabled should be considered an error, but in order to maintain legacy
+	// behavior we have to require an opt-in to this error for a period of time.
+	// If there is more than one line (table headers) in /proc/swaps, swap is enabled and we should
+	// error out unless --fail-swap-on is set to false.
 	if len(buf) > 1 {
 		if failSwapOn {
-			return nil, fmt.Errorf("Running with swap on is not supported, please disable swap! /proc/swaps contained: %v", buf)
+			return nil, fmt.Errorf("Running with swap on is not supported, please disable swap! or set --fail-swap-on flag to false. /proc/swaps contained: %v", buf)
 		}
-		glog.Warningf("Running with swap on is not supported, please disable swap! " +
-			"This will be a fatal error by default starting in K8s v1.6! " +
-			"In the meantime, you can opt-in to making this a fatal error by enabling --experimental-fail-swap-on.")
 	}
 	var capacity = v1.ResourceList{}
 	// It is safe to invoke `MachineInfo` on cAdvisor before logically initializing cAdvisor here because