CustomResources dropping "null" values from arrays #98080
Description
What happened:
While attempting to work around #98079, I encountered an issue where data was not preserved when writing a custom resource instance to the apiserver with kubectl.
Specifically, I am using a CRD that has a properly which is an array of values which can either be an integer, or null:
spec:
properties:
allocations:
items:
nullable: true
type: integer
type: array
When using kubectl to modify the resource, all of the "null" values are lost upon write. So, if I attempt to write a resource with the following:
allocations:
- 1
- 5
- null
- null
It is written successfully. However, when I query the resource from the API afterwards, this is what I get back:
allocations:
- 1
- 5
The null entries have been lost.
What you expected to happen:
The null entries in the array should be maintained.
How to reproduce it (as minimally and precisely as possible):
Create a CustomResourceDefinition with a property like the one specified above, and create an instance of it (you may need to pass --validate=false in order to bypass the bug in #98079).
Notice that null values are removed from the array.
Anything else we need to know?:
Environment:
- Kubernetes version (use
kubectl version):
Client Version: version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.8", GitCommit:"9f2892aab98fe339f3bd70e3c470144299398ace", GitTreeState:"clean", BuildDate:"2020-08-13T16:12:48Z", GoVersion:"go1.13.15", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.2", GitCommit:"52c56ce7a8272c798dbc29846288d7cd9fbae032", GitTreeState:"clean", BuildDate:"2020-04-30T20:19:45Z", GoVersion:"go1.13.9", Compiler:"gc", Platform:"linux/amd64"}
Also reproduced on master by @liggitt
/sig api-machinery