Note: Dockershim has been removed from the Kubernetes project as of release 1.24. Read the Dockershim Removal FAQ for further details. FEATURE STATE: Kubernetes v1.11 [stable] The lifecycle of the kubeadm CLI tool is decoupled from the kubelet, which is a daemon that runs on each node within the Kubernetes cluster. The kubeadm CLI tool is executed by the user when Kubernetes is initialized or upgraded, whereas the kubelet is always running in the background.

Understand Pods, the smallest deployable compute object in Kubernetes, and the higher-level abstractions that help you to run them.

Finalizers are namespaced keys that tell Kubernetes to wait until specific conditions are met before it fully deletes resources marked for deletion. Finalizers alert controllers to clean up resources the deleted object owned. When you tell Kubernetes to delete an object that has finalizers specified for it, the Kubernetes API marks the object for deletion by populating .metadata.deletionTimestamp, and returns a 202 status code (HTTP "Accepted"). The target object remains in a terminating state while the control plane, or other components, take the actions defined by the finalizers.

The architectural concepts behind Kubernetes.

Garbage collection is a collective term for the various mechanisms Kubernetes uses to clean up cluster resources. This allows the clean up of resources like the following: Terminated pods Completed Jobs Objects without owner references Unused containers and container images Dynamically provisioned PersistentVolumes with a StorageClass reclaim policy of Delete Stale or expired CertificateSigningRequests (CSRs) Nodes deleted in the following scenarios: On a cloud when the cluster uses a cloud controller manager On-premises when the cluster uses an addon similar to a cloud controller manager Node Lease objects Owners and dependents Many objects in Kubernetes link to each other through owner references.

This page shows you how to specify the type of cascading deletion to use in your cluster during garbage collection. Before you begin You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts. If you do not already have a cluster, you can create one by using minikube or you can use one of these Kubernetes playgrounds:

Kubernetes objects can be created, updated, and deleted by storing multiple object configuration files in a directory and using kubectl apply to recursively create and update those objects as needed. This method retains writes made to live objects without merging the changes back into the object configuration files. kubectl diff also gives you a preview of what changes apply will make. Before you begin Install kubectl. You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster.

FEATURE STATE: Kubernetes v1.32 [beta] (enabled by default: false) This page shows you how to configure dynamic resource allocation (DRA) in a Kubernetes cluster by enabling API groups and configuring classes of devices. These instructions are for cluster administrators. About DRA A Kubernetes feature that lets you request and share resources among Pods. These resources are often attached devices like hardware accelerators. With DRA, device drivers and cluster admins define device classes that are available to claim in workloads.

Configuring the aggregation layer allows the Kubernetes apiserver to be extended with additional APIs, which are not part of the core Kubernetes APIs. Before you begin You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts. If you do not already have a cluster, you can create one by using minikube or you can use one of these Kubernetes playgrounds:

In addition to compiled-in admission plugins, admission plugins can be developed as extensions and run as webhooks configured at runtime. This page describes how to build, configure, use, and monitor admission webhooks. What are admission webhooks? Admission webhooks are HTTP callbacks that receive admission requests and do something with them. You can define two types of admission webhooks, validating admission webhook and mutating admission webhook. Mutating admission webhooks are invoked first, and can modify objects sent to the API server to enforce custom defaults.