Note: This section links to third party projects that provide functionality required by Kubernetes. The Kubernetes project authors aren't responsible for these projects, which are listed alphabetically. To add a project to this list, read the content guide before submitting a change. More information. Kubernetes applications usually consist of multiple, separate services, each running in its own container. Developing and debugging these services on a remote Kubernetes cluster can be cumbersome, requiring you to get a shell on a running container in order to run debugging tools.

This page shows how to investigate problems related to the execution of Init Containers. The example command lines below refer to the Pod as <pod-name> and the Init Containers as <init-container-1> and <init-container-2>. 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.

A ReplicaSet's purpose is to maintain a stable set of replica Pods running at any given time. Usually, you define a Deployment and let that Deployment manage ReplicaSets automatically.

FEATURE STATE: Kubernetes v1.11 [beta] Cloud infrastructure technologies let you run Kubernetes on public, private, and hybrid clouds. Kubernetes believes in automated, API-driven infrastructure without tight coupling between components. The cloud-controller-manager is a Kubernetes control plane component that embeds cloud-specific control logic. The cloud controller manager lets you link your cluster into your cloud provider's API, and separates out the components that interact with that cloud platform from components that only interact with your cluster.

FEATURE STATE: Kubernetes v1.23 [stable] Your Kubernetes cluster includes dual-stack networking, which means that cluster networking lets you use either address family. In a cluster, the control plane can assign both an IPv4 address and an IPv6 address to a single Pod or a Service. Before you begin You need to have installed the kubeadm tool, following the steps from Installing kubeadm. For each server that you want to use as a node, make sure it allows IPv6 forwarding.

FEATURE STATE: Kubernetes v1.25 [stable] This page provides an overview of ephemeral containers: a special type of container that runs temporarily in an existing Pod to accomplish user-initiated actions such as troubleshooting. You use ephemeral containers to inspect services rather than to build applications. Understanding ephemeral containers Pods are the fundamental building block of Kubernetes applications. Since Pods are intended to be disposable and replaceable, you cannot add a container to a Pod once it has been created.

This page explains the two options for configuring the topology of your highly available (HA) Kubernetes clusters. You can set up an HA cluster: With stacked control plane nodes, where etcd nodes are colocated with control plane nodes With external etcd nodes, where etcd runs on separate nodes from the control plane You should carefully consider the advantages and disadvantages of each topology before setting up an HA cluster.

FEATURE STATE: Kubernetes v1.29 [stable] Controlling the behavior of the Kubernetes API server in an overload situation is a key task for cluster administrators. The kube-apiserver has some controls available (i.e. the --max-requests-inflight and --max-mutating-requests-inflight command-line flags) to limit the amount of outstanding work that will be accepted, preventing a flood of inbound requests from overloading and potentially crashing the API server, but these flags are not enough to ensure that the most important requests get through in a period of high traffic.

Node affinity is a property of Pods that attracts them to a set of nodes (either as a preference or a hard requirement). Taints are the opposite -- they allow a node to repel a set of pods. Tolerations are applied to pods. Tolerations allow the scheduler to schedule pods with matching taints. Tolerations allow scheduling but don't guarantee scheduling: the scheduler also evaluates other parameters as part of its function.

This page provides a step-by-step example of updating configuration within a Pod via a ConfigMap and builds upon the Configure a Pod to Use a ConfigMap task. At the end of this tutorial, you will understand how to change the configuration for a running application. This tutorial uses the alpine and nginx images as examples. Before you begin You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster.