Synopsis The Kubernetes controller manager is a daemon that embeds the core control loops shipped with Kubernetes. In applications of robotics and automation, a control loop is a non-terminating loop that regulates the state of the system. In Kubernetes, a controller is a control loop that watches the shared state of the cluster through the apiserver and makes changes attempting to move the current state towards the desired state. Examples of controllers that ship with Kubernetes today are the replication controller, endpoints controller, namespace controller, and serviceaccounts controller.

This page shows how to create a new topic for the Kubernetes docs. Before you begin Create a fork of the Kubernetes documentation repository as described in Open a PR. Choosing a page type As you prepare to write a new topic, think about the page type that would fit your content the best: Guidelines for choosing a page type Type Description Concept A concept page explains some aspect of Kubernetes.

This site uses Hugo. In Hugo, content organization is a core concept. Note:Hugo Tip: Start Hugo with hugo server --navigateToChanged for content edit-sessions. Page Lists Page Order The documentation side menu, the documentation page browser etc. are listed using Hugo's default sort order, which sorts by weight (from 1), date (newest first), and finally by the link title. Given that, if you want to move a page or a section up, set a weight in the page's front matter:

FEATURE STATE: Kubernetes v1.26 [stable] Starting from Kubernetes v1.20, the kubelet can dynamically retrieve credentials for a container image registry using exec plugins. The kubelet and the exec plugin communicate through stdio (stdin, stdout, and stderr) using Kubernetes versioned APIs. These plugins allow the kubelet to request credentials for a container registry dynamically as opposed to storing static credentials on disk. For example, the plugin may talk to a local metadata server to retrieve short-lived credentials for an image that is being pulled by the kubelet.

FEATURE STATE: Kubernetes v1.26 [stable] Kubernetes keeps many aspects of how pods execute on nodes abstracted from the user. This is by design. However, some workloads require stronger guarantees in terms of latency and/or performance in order to operate acceptably. The kubelet provides methods to enable more complex workload placement policies while keeping the abstraction free from explicit placement directives. For detailed information on resource management, please refer to the Resource Management for Pods and Containers documentation.

This page shows how to access clusters using the Kubernetes API. 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:

Restrict how many Pods you can create within a namespace.

The aggregation layer allows Kubernetes to be extended with additional APIs, beyond what is offered by the core Kubernetes APIs. The additional APIs can either be ready-made solutions such as a metrics server, or APIs that you develop yourself. The aggregation layer is different from Custom Resource Definitions, which are a way to make the kube-apiserver recognise new kinds of object. Aggregation layer The aggregation layer runs in-process with the kube-apiserver.

Use kubectl patch to update Kubernetes API objects in place. Do a strategic merge patch or a JSON merge patch.

Static Pods are managed directly by the kubelet daemon on a specific node, without the API server observing them. Unlike Pods that are managed by the control plane (for example, a Deployment); instead, the kubelet watches each static Pod (and restarts it if it fails). Static Pods are always bound to one Kubelet on a specific node. The kubelet automatically tries to create a mirror Pod on the Kubernetes API server for each static Pod.