Fresh Swap Features for Linux Users in Kubernetes 1.32

Fresh Swap Features for Linux Users in Kubernetes 1.32 How do I use it? Install a swap-enabled cluster with kubeadm Before you begin Create a swap file and turn swap on Set up a Kubernetes cluster that uses swap-enabled nodes How is the swap limit being determined with LimitedSwap? How does it work? How can I monitor swap? Node and container level metric statistics Node Feature Discovery (NFD) Caveats Memory-backed volumes Good practice for using swap in a Kubernetes cluster Disable swap for system-critical daemons Protect system-critical daemons for I/O latency Swap and control plane nodes Use of a dedicated disk for swap Looking ahead How can I learn more? How do I get involved? Swap is a fundamental and an invaluable Linux feature. It offers numerous benefits, such as effectively increasing a node’s memory by swapping out unused data, shielding nodes from system-level memory spikes, preventing Pods from crashing when they hit their memory limits, and much more. As a result, the node special interest group within the Kubernetes project has invested significant effort into supporting swap on Linux nodes. The 1.22 release introduced Alpha support for configuring swap memory usage for Kubernetes workloads running on Linux on a per-node basis. Later, in release 1.28, support for swap on Linux nodes has graduated to Beta, along with many new improvements. In the following Kubernetes releases more improvements were made, paving the way to GA in the near future. Prior to version 1.22, Kubernetes did not provide support for swap memory on Linux systems. This was due to the inherent difficulty in guaranteeing and accounting for pod memory utilization when swap memory was involved. As a result, swap support was deemed out of scope in the initial design of Kubernetes, and the default behavior of a kubelet was to fail to start if swap memory was detected on a node. In version 1.22, the swap feature for Linux was initially introduced in its Alpha stage. This provided Linux users the opportunity to experiment with the swap feature for the first time. However, as an Alpha version, it was not fully developed and only partially worked on limited environments.