Distributed systems often have a need for leases, which provide a mechanism to lock shared resources and coordinate activity between members of a set. In Kubernetes, the lease concept is represented by Lease objects in the coordination.k8s.io API Group, which are used for system-critical capabilities such as node heartbeats and component-level leader election. Node heartbeats Kubernetes uses the Lease API to communicate kubelet node heartbeats to the Kubernetes API server.

A ConfigMap is an API object used to store non-confidential data in key-value pairs. Pods can consume ConfigMaps as environment variables, command-line arguments, or as configuration files in a volume. A ConfigMap allows you to decouple environment-specific configuration from your container images, so that your applications are easily portable. Caution:ConfigMap does not provide secrecy or encryption. If the data you want to store are confidential, use a Secret rather than a ConfigMap, or use additional (third party) tools to keep your data private.

FEATURE STATE: Kubernetes v1.20 [stable] This page describes the RuntimeClass resource and runtime selection mechanism. RuntimeClass is a feature for selecting the container runtime configuration. The container runtime configuration is used to run a Pod's containers. Motivation You can set a different RuntimeClass between different Pods to provide a balance of performance versus security. For example, if part of your workload deserves a high level of information security assurance, you might choose to schedule those Pods so that they run in a container runtime that uses hardware virtualization.

Kubernetes has various types of probes: Liveness probe Readiness probe Startup probe Liveness probe Liveness probes determine when to restart a container. For example, liveness probes could catch a deadlock when an application is running but unable to make progress. If a container fails its liveness probe repeatedly, the kubelet restarts the container. Liveness probes do not wait for readiness probes to succeed. If you want to wait before executing a liveness probe, you can either define initialDelaySeconds or use a startup probe.

In order to support latency-critical and high-throughput workloads, Kubernetes offers a suite of Resource Managers. The managers aim to co-ordinate and optimise the alignment of node's resources for pods configured with a specific requirement for CPUs, devices, and memory (hugepages) resources. Hardware topology alignment policies Topology Manager is a kubelet component that aims to coordinate the set of components that are responsible for these optimizations. The overall resource management process is governed using the policy you specify.

FEATURE STATE: Kubernetes v1.20 [stable] Kubernetes allow you to limit the number of process IDs (PIDs) that a Pod can use. You can also reserve a number of allocatable PIDs for each node for use by the operating system and daemons (rather than by Pods). Process IDs (PIDs) are a fundamental resource on nodes. It is trivial to hit the task limit without hitting any other resource limits, which can then cause instability to a host machine.

FEATURE STATE: Kubernetes v1.34 [stable](enabled by default) This page assumes that you are familiar with StorageClasses, volumes and PersistentVolumes in Kubernetes. A VolumeAttributesClass provides a way for administrators to describe the mutable "classes" of storage they offer. Different classes might map to different quality-of-service levels. Kubernetes itself is un-opinionated about what these classes represent. This feature is generally available (GA) as of version 1.34, and users have the option to disable it.

Before you begin You must use a kubectl version that is within one minor version difference of your cluster. For example, a v1.34 client can communicate with v1.33, v1.34, and v1.35 control planes. Using the latest compatible version of kubectl helps avoid unforeseen issues. Install kubectl on Linux The following methods exist for installing kubectl on Linux: Install kubectl binary with curl on Linux Install using native package management Install using other package management Install kubectl binary with curl on Linux Download the latest release with the command:

kubeadm does not support automated ways of reconfiguring components that were deployed on managed nodes. One way of automating this would be by using a custom operator. To modify the components configuration you must manually edit associated cluster objects and files on disk. This guide shows the correct sequence of steps that need to be performed to achieve kubeadm cluster reconfiguration. Before you begin You need a cluster that was deployed using kubeadm Have administrator credentials (/etc/kubernetes/admin.

This page shows how to use Kube-router for NetworkPolicy. Before you begin You need to have a Kubernetes cluster running. If you do not already have a cluster, you can create one by using any of the cluster installers like Kops, Bootkube, Kubeadm etc. Installing Kube-router addon The Kube-router Addon comes with a Network Policy Controller that watches Kubernetes API server for any NetworkPolicy and pods updated and configures iptables rules and ipsets to allow or block traffic as directed by the policies.