This guide is for application owners who want to build highly available applications, and thus need to understand what types of disruptions can happen to Pods. It is also for cluster administrators who want to perform automated cluster actions, like upgrading and autoscaling clusters. Voluntary and involuntary disruptions Pods do not disappear until someone (a person or a controller) destroys them, or there is an unavoidable hardware or system software error.

This document describes ephemeral volumes in Kubernetes. Familiarity with volumes is suggested, in particular PersistentVolumeClaim and PersistentVolume. Some applications need additional storage but don't care whether that data is stored persistently across restarts. For example, caching services are often limited by memory size and can move infrequently used data into storage that is slower than memory with little impact on overall performance. Other applications expect some read-only input data to be present in files, like configuration data or secret keys.

This page covers advanced Pod configuration topics including PriorityClasses, RuntimeClasses, security context within Pods, and introduces aspects of scheduling. PriorityClasses PriorityClasses allow you to set the importance of Pods relative to other Pods. If you assign a priority class to a Pod, Kubernetes sets the .spec.priority field for that Pod based on the PriorityClass you specified (you cannot set .spec.priority directly). If or when a Pod cannot be scheduled, and the problem is due to a lack of resources, the kube-scheduler tries to preempt lower priority Pods, in order to make scheduling of the higher priority Pod possible.

FEATURE STATE: Kubernetes v1.32 [stable](enabled by default) The Kubernetes Memory Manager enables the feature of guaranteed memory (and hugepages) allocation for pods in the Guaranteed QoS class. The Memory Manager employs a hint generation protocol to yield the most suitable NUMA affinity for a pod. The Memory Manager feeds the central manager (Topology Manager) with these affinity hints. Based on both the hints and Topology Manager policy, the pod is rejected or admitted to the node.

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.

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. By decoupling the interoperability logic between Kubernetes and the underlying cloud infrastructure, the cloud-controller-manager component enables cloud providers to release features at a different pace compared to the main Kubernetes project.

Prometheus project documentation for HTTP API

Prometheus project documentation for Native Histograms

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