Feature Gates

This page contains an overview of the various feature gates an administratorcan specify on different Kubernetes components.

See feature stages for an explanation of the stages for a feature.

Overview

Feature gates are a set of key=value pairs that describe Kubernetes features.You can turn these features on or off using the —feature-gates command line flagon each Kubernetes component.

Each Kubernetes component lets you enable or disable a set of feature gates thatare relevant to that component.Use -h flag to see a full set of feature gates for all components.To set feature gates for a component, such as kubelet, use the —feature-gates flag assigned to a list of feature pairs:

--feature-gates="...,DynamicKubeletConfig=true"

The following tables are a summary of the feature gates that you can set ondifferent Kubernetes components.

• The “Since” column contains the Kubernetes release when a feature is introducedor its release stage is changed.
• The “Until” column, if not empty, contains the last Kubernetes release in whichyou can still use a feature gate.
• If a feature is in the Alpha or Beta state, you can find the feature listedin the Alpha/Beta feature gate table.
• If a feature is stable you can find all stages for that feature listed in theGraduated/Deprecated feature gate table.
• The Graduated/Deprecated feature gate table.also lists deprecated and withdrawn features.

Feature gates for Alpha or Beta features

Feature gates for graduated or deprecated features

Using a feature

Feature stages

A feature can be in Alpha, Beta or GA stage.An Alpha feature means:

• Disabled by default.
• Might be buggy. Enabling the feature may expose bugs.
• Support for feature may be dropped at any time without notice.
• The API may change in incompatible ways in a later software release without notice.
• Recommended for use only in short-lived testing clusters, due to increasedrisk of bugs and lack of long-term support.

A Beta feature means:

• Enabled by default.
• The feature is well tested. Enabling the feature is considered safe.
• Support for the overall feature will not be dropped, though details may change.
• The schema and/or semantics of objects may change in incompatible ways in asubsequent beta or stable release. When this happens, we will provide instructionsfor migrating to the next version. This may require deleting, editing, andre-creating API objects. The editing process may require some thought.This may require downtime for applications that rely on the feature.
• Recommended for only non-business-critical uses because of potential forincompatible changes in subsequent releases. If you have multiple clustersthat can be upgraded independently, you may be able to relax this restriction.

Note: Please do try Beta features and give feedback on them!After they exit beta, it may not be practical for us to make more changes.

A General Availability (GA) feature is also referred to as a stable feature. It means:

• The feature is always enabled; you cannot disable it.
• The corresponding feature gate is no longer needed.
• Stable versions of features will appear in released software for many subsequent versions.

List of feature gates

Each feature gate is designed for enabling/disabling a specific feature:

• Accelerators: Enable Nvidia GPU support when using Docker
• AdvancedAuditing: Enable advanced auditing
• AffinityInAnnotations(deprecated): Enable setting Pod affinity or anti-affinitys.
• AllowExtTrafficLocalEndpoints: Enable a service to route external requests to node local endpoints.
• APIListChunking: Enable the API clients to retrieve (LIST or GET) resources from API server in chunks.
• APIResponseCompression: Compress the API responses for LIST or GET requests.
• AppArmor: Enable AppArmor based mandatory access control on Linux nodes when using Docker.See AppArmor Tutorial for more details.
• AttachVolumeLimit: Enable volume plugins to report limits on number of volumesthat can be attached to a node.See dynamic volume limits for more details.
• BalanceAttachedNodeVolumes: Include volume count on node to be considered for balanced resource allocationwhile scheduling. A node which has closer CPU, memory utilization, and volume count is favored by the schedulerwhile making decisions.
• BlockVolume: Enable the definition and consumption of raw block devices in Pods.See Raw Block Volume Supportfor more details.
• BoundServiceAccountTokenVolume: Migrate ServiceAccount volumes to use a projected volume consisting of aServiceAccountTokenVolumeProjection.Check Service Account Token Volumesfor more details.
• CPUManager: Enable container level CPU affinity support, see CPU Management Policies.
• CRIContainerLogRotation: Enable container log rotation for cri container runtime.
• CSIBlockVolume: Enable external CSI volume drivers to support block storage. See the csi raw block volume support documentation for more details.
• CSIDriverRegistry: Enable all logic related to the CSIDriver API object in csi.storage.k8s.io.
• CSIInlineVolume: Enable CSI Inline volumes support for pods.
• CSIMigration: Enables shims and translation logic to route volume operations from in-tree plugins to corresponding pre-installed CSI plugins
• CSIMigrationAWS: Enables shims and translation logic to route volume operations from the AWS-EBS in-tree plugin to EBS CSI plugin
• CSIMigrationAzureDisk: Enables shims and translation logic to route volume operations from the Azure-Disk in-tree plugin to Azure Disk CSI plugin
• CSIMigrationAzureFile: Enables shims and translation logic to route volume operations from the Azure-File in-tree plugin to Azure File CSI plugin
• CSIMigrationGCE: Enables shims and translation logic to route volume operations from the GCE-PD in-tree plugin to PD CSI plugin
• CSIMigrationOpenStack: Enables shims and translation logic to route volume operations from the Cinder in-tree plugin to Cinder CSI plugin
• CSINodeInfo: Enable all logic related to the CSINodeInfo API object in csi.storage.k8s.io.
• CSIPersistentVolume: Enable discovering and mounting volumes provisioned through aCSI (Container Storage Interface)compatible volume plugin.Check the csi volume type documentation for more details.
• CustomCPUCFSQuotaPeriod: Enable nodes to change CPUCFSQuotaPeriod.
• CustomPodDNS: Enable customizing the DNS settings for a Pod using its dnsConfig property.Check Pod’s DNS Configfor more details.
• CustomResourceDefaulting: Enable CRD support for default values in OpenAPI v3 validation schemas.
• CustomResourcePublishOpenAPI: Enables publishing of CRD OpenAPI specs.
• CustomResourceSubresources: Enable /status and /scale subresourceson resources created from CustomResourceDefinition.
• CustomResourceValidation: Enable schema based validation on resources created fromCustomResourceDefinition.
• CustomResourceWebhookConversion: Enable webhook-based conversionon resources created from CustomResourceDefinition.troubleshoot a running Pod.
• DevicePlugins: Enable the device-pluginsbased resource provisioning on nodes.
• DryRun: Enable server-side dry run requestsso that validation, merging, and mutation can be tested without committing.
• DynamicAuditing: Enable dynamic auditing
• DynamicKubeletConfig: Enable the dynamic configuration of kubelet. See Reconfigure kubelet.
• DynamicProvisioningScheduling: Extend the default scheduler to be aware of volume topology and handle PV provisioning.This feature is superceded by the VolumeScheduling feature completely in v1.12.
• DynamicVolumeProvisioning(deprecated): Enable the dynamic provisioning of persistent volumes to Pods.
• EnableAggregatedDiscoveryTimeout (deprecated): Enable the five second timeout on aggregated discovery calls.
• EnableEquivalenceClassCache: Enable the scheduler to cache equivalence of nodes when scheduling Pods.
• EphemeralContainers: Enable the ability to add ephemeral containersA type of container type that you can temporarily run inside a Pod to running pods.
• EvenPodsSpread: Enable pods to be scheduled evenly across topology domains. See Even Pods Spread.
• ExpandInUsePersistentVolumes: Enable expanding in-use PVCs. See Resizing an in-use PersistentVolumeClaim.
• ExpandPersistentVolumes: Enable the expanding of persistent volumes. See Expanding Persistent Volumes Claims.
• ExperimentalCriticalPodAnnotation: Enable annotating specific pods as critical so that their scheduling is guaranteed.This feature is deprecated by Pod Priority and Preemption as of v1.13.
• ExperimentalHostUserNamespaceDefaultingGate: Enabling the defaulting usernamespace to host. This is for containers that are using other host namespaces,host mounts, or containers that are privileged or using specific non-namespacedcapabilities (e.g. MKNODE, SYS_MODULE etc.). This should only be enabledif user namespace remapping is enabled in the Docker daemon.
• EndpointSlice: Enables Endpoint Slices for more scalable and extensiblenetwork endpoints. Requires corresponding API and Controller to be enabled.See Enabling Endpoint Slices.
• GCERegionalPersistentDisk: Enable the regional PD feature on GCE.
• HugePages: Enable the allocation and consumption of pre-allocated huge pages.
• HyperVContainer: Enable Hyper-V isolation for Windows containers.
• HPAScaleToZero: Enables setting minReplicas to 0 for HorizontalPodAutoscaler resources when using custom or external metrics.
• KubeletConfigFile: Enable loading kubelet configuration from a file specified using a config file.See setting kubelet parameters via a config file for more details.
• KubeletPluginsWatcher: Enable probe-based plugin watcher utility to enable kubeletto discover plugins such as CSI volume drivers.
• KubeletPodResources: Enable the kubelet’s pod resources grpc endpoint.See Support Device Monitoring for more details.
• LegacyNodeRoleBehavior: When disabled, legacy behavior in service load balancers and node disruption will ignore the node-role.kubernetes.io/master label in favor of the feature-specific labels.
• LocalStorageCapacityIsolation: Enable the consumption of local ephemeral storage and also the sizeLimit property of an emptyDir volume.
• LocalStorageCapacityIsolationFSQuotaMonitoring: When LocalStorageCapacityIsolation is enabled for local ephemeral storage and the backing filesystem for emptyDir volumes supports project quotas and they are enabled, use project quotas to monitor emptyDir volume storage consumption rather than filesystem walk for better performance and accuracy.
• MountContainers: Enable using utility containers on host as the volume mounter.
• MountPropagation: Enable sharing volume mounted by one container to other containers or pods.For more details, please see mount propagation.
• NodeDisruptionExclusion: Enable use of the node label node.kubernetes.io/exclude-disruption which prevents nodes from being evacuated during zone failures.
• NodeLease: Enable the new Lease API to report node heartbeats, which could be used as a node health signal.
• NonPreemptingPriority: Enable NonPreempting option for PriorityClass and Pod.
• PersistentLocalVolumes: Enable the usage of local volume type in Pods.Pod affinity has to be specified if requesting a local volume.
• PodOverhead: Enable the PodOverhead feature to account for pod overheads.
• PodPriority: Enable the descheduling and preemption of Pods based on their priorities.
• PodReadinessGates: Enable the setting of PodReadinessGate field for extendingPod readiness evaluation. See Pod readiness gatefor more details.
• PodShareProcessNamespace: Enable the setting of shareProcessNamespace in a Pod for sharinga single process namespace between containers running in a pod. More details can be found inShare Process Namespace between Containers in a Pod.
• ProcMountType: Enables control over ProcMountType for containers.
• PVCProtection: Enable the prevention of a PersistentVolumeClaim (PVC) frombeing deleted when it is still used by any Pod.
• QOSReserved: Allows resource reservations at the QoS level preventing pods at lower QoS levels frombursting into resources requested at higher QoS levels (memory only for now).
• ResourceLimitsPriorityFunction: Enable a scheduler priority function thatassigns a lowest possible score of 1 to a node that satisfies at least one ofthe input Pod’s cpu and memory limits. The intent is to break ties betweennodes with same scores.
• RequestManagement: Enable managing request concurrency with prioritization and fairness at each server.
• ResourceQuotaScopeSelectors: Enable resource quota scope selectors.
• RotateKubeletClientCertificate: Enable the rotation of the client TLS certificate on the kubelet.See kubelet configuration for more details.
• RotateKubeletServerCertificate: Enable the rotation of the server TLS certificate on the kubelet.See kubelet configuration for more details.
• RunAsGroup: Enable control over the primary group ID set on the init processes of containers.
• RuntimeClass: Enable the RuntimeClass feature for selecting container runtime configurations.
• ScheduleDaemonSetPods: Enable DaemonSet Pods to be scheduled by the default scheduler instead of the DaemonSet controller.
• SCTPSupport: Enables the usage of SCTP as protocol value in Service, Endpoint, NetworkPolicy and Pod definitions
• ServerSideApply: Enables the Sever Side Apply (SSA) path at the API Server.
• ServiceLoadBalancerFinalizer: Enable finalizer protection for Service load balancers.
• ServiceNodeExclusion: Enable the exclusion of nodes from load balancers created by a cloud provider.A node is eligible for exclusion if labelled with “alpha.service-controller.kubernetes.io/exclude-balancer” key (when LegacyNodeRoleBehavior is on) or node.kubernetes.io/exclude-from-external-load-balancers.
• StartupProbe: Enable the startup probe in the kubelet.
• StorageObjectInUseProtection: Postpone the deletion of PersistentVolume orPersistentVolumeClaim objects if they are still being used.
• StorageVersionHash: Allow apiservers to expose the storage version hash in the discovery.
• StreamingProxyRedirects: Instructs the API server to intercept (and follow)redirects from the backend (kubelet) for streaming requests.Examples of streaming requests include the exec, attach and port-forward requests.
• SupportIPVSProxyMode: Enable providing in-cluster service load balancing using IPVS.See service proxies for more details.
• SupportPodPidsLimit: Enable the support to limiting PIDs in Pods.
• Sysctls: Enable support for namespaced kernel parameters (sysctls) that can be set for each pod.See sysctls for more details.
• TaintBasedEvictions: Enable evicting pods from nodes based on taints on nodes and tolerations on Pods.See taints and tolerations for more details.
• TaintNodesByCondition: Enable automatic tainting nodes based on node conditions.
• TokenRequest: Enable the TokenRequest endpoint on service account resources.
• TokenRequestProjection: Enable the injection of service account tokens intoa Pod through the projected volume.
• TopologyManager: Enable a mechanism to coordinate fine-grained hardware resource assignments for different components in Kubernetes. See Control Topology Management Policies on a node.
• TTLAfterFinished: Allow a TTL controller to clean up resources after they finish execution.
• VolumePVCDataSource: Enable support for specifying an existing PVC as a DataSource.
• VolumeScheduling: Enable volume topology aware scheduling and make thePersistentVolumeClaim (PVC) binding aware of scheduling decisions. It alsoenables the usage of local volumetype when used together with the PersistentLocalVolumes feature gate.
• VolumeSnapshotDataSource: Enable volume snapshot data source support.
• VolumeSubpathEnvExpansion: Enable subPathExpr field for expanding environment variables into a subPath.
• WatchBookmark: Enable support for watch bookmark events.
• WindowsGMSA: Enables passing of GMSA credential specs from pods to container runtimes.
• WinDSR: Allows kube-proxy to create DSR loadbalancers for Windows.
• WinOverlay: Allows kube-proxy to run in overlay mode for Windows.

What's next

• The deprecation policy for Kubernetes explainsthe project’s approach to removing features and components.

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