# Kyverno API

This document provides guidance on extending and maintaining the [Kyverno API](../../../api/kyverno/)

## Concepts
* https://kubernetes.io/docs/reference/using-api/api-concepts/ 
* https://kubernetes.io/docs/reference/using-api/ 
* https://kubernetes.io/docs/tasks/extend-kubernetes/custom-resources/custom-resource-definition-versioning/

## API Groups 

All Kyverno resources are currently defined in the `kyverno.io` API group. 

## API Versions

This `kyverno.io` has the following versions:
* v1apha1  
* v1apha2 
* v1beta1 
* v1 
* v2Beta1 

The `v1` version is currently the preferred storage version, but is being deprecated. 

The goal is to eventually make v2 the preferred version and remove all v1* versions.


## Adding a new Kind (Resource)

New types should not be added to `v1` but should be introduced as `v2alpha1` and then promoted as they stabilize.

## Adding a new attribute

New attributes can be added to existing resources without impacting compatibility. They do not require a new version.

## Deleting an attribute

Attributes cannot be deleted in a version. They should be marked for deprecation and removed after 3 minor releases.

## Modifying an attribute

Attributes cannot be modified in a version. The existing attribute should be marked for deprecation and a new attribute should be added following version compatibity guidelines.


## Stable References

Within the API, newer versions can reference older stable types, but not the other way around. For example, a `v1` resource should not refer to a `v2alpha1` type. However, a `v2alpha1` type can reference `v1` types.