Kubewarden policy deprecated-api-versions

Description

This policy detects usage of Kubernetes resources that have been deprecated or removed.

At deployment time, the operator must provide a Kubernetes version to use when looking for deprecation/removal objects. This is done via the kubernetes_version attribute.

For example, given the following configuration:

kubernetes_version: "1.24.2"

The policy will detect all the Kubernetes resources that are deprecated or removed starting from the Kubernetes version 1.24.2.

Deprecated but not yet removed resources

By default the policy will prevent the usage of Kubernetes resources that are already deprecated, but not yet removed.

This behaviour can be changed via the deny_on_deprecation setting.

For example, let's assume we are using an old version of Kubernetes like 1.19.3 and someone is attempting to create a extensions/v1beta1/Ingress object.

This kind of resource has been deprecated starting from v1.14.0 of Kubernetes, but it has been removed starting from version v1.22.0.

Given the following configuration:

kubernetes_version: "1.19.0"
deny_on_deprecation: false

The extensions/v1beta1/Ingress object will be accepted inside of the cluster.

On the other hand, it would be blocked with this configuration:

kubernetes_version: "1.19.0"
deny_on_deprecation: true # note: this is set to true by default

Keeping up with Kubernetes deprecations

Kubernetes deprecation evolve over the time. As soon as new deprecations are added this policy will be updated.

The versioning scheme of this policy follows this pattern:

<policy version>-k8sv<most recent version of kubernes known by the embedded deprecation rules>

For example, the release 0.1.0-k8sv1.26.0 of this policy knows about all the deprecation rules formulated up to Kubernetes release 1.26.0.

The announcement of new deprecation rules for Kubernetes 1.27.0 would trigger then a release of this policy with the following version: v0.1.1-k8sv1.27.0.