Kubernetes 1.15 Release Delivers 25 Enhancements -- Virtualization Review

Kubernetes 1.15 Release Delivers 25 Enhancements

By Wendy A. Hernandez
06/19/2019

Today the Kubernetes 1.15 Release Team announced the delivery of Kubernetes 1.15, which is the second release this year. According to the blog announcement, the release includes 25 different enhancements -- which include two that have moved to stable, 13 moving into beta and 10 in alpha -- that cover the main themes of continuous improvement and extensibility.

Stable enhancements that were highlighted in the announcement include kubeadm, which "continues to receive features and stability work required for bootstrapping production clusters efficiently." The cluster lifecycle building block has also helped promote high availability (HA) capability to beta, and allows users to use the kubeadm init and kubeadm join commands to configure and deploy an HA control plane.

Notable beta enhancements include:

CustomResourceDefinition Webhook Conversion, which can now convert between different versions on-the-fly via webhooks, and are deployed inside the cluster by the cluster admin.

CustomResourceDefinition OpenAPI Publishing, available only for structural schemas.

CustomResourceDefinitions Pruning, the automatic removal of unknown fields in objects sent to a Kubernetes API, which is a behavior found in native resources, will now be available. It will require that CRD developer provide "complete, structural validation schemas, either top-level or for all versions of the CRD."

Admission Webhook Reinvocation & Improvements include the ability for mutating webhooks to now opt-in to at least one re-invocation by specifying 'reinvocationPolicy: IfNeeded.' If a later mutating webhook modifies the object, the earlier webhook will get a second chance. Before 1.15, webhooks were only called once, in alphabetical order, and an earlier run webhook couldn't react on the output of webhooks called later in the chain.

The main alpha highlight was CustomResourceDefinitions getting support for Defaulting. As explained in the announcement: "Defaults are specified using the 'default' keyword in the OpenAPI validation schema. Defaults are set for unspecified field in an object sent to the API, and when reading from etcd."

The team has a "Days of Kubernetes" blog series scheduled, which will highlight walk-throughs of the following: