Add support for kubecrd style dataclasses for creating CRDs

[jacobtomlinson]

Which project are you requesting an enhancement for?

kr8s

What do you need?

The kubecrd project allows you to define a Custom Resource Definition (CRD) as a Python dataclass and then export the YAML.

Today I noticed a project where someone is using kubecrd with kr8s and they are creating a custom kr8s API object from the kubecrd dataclass.

Something like this

from dataclasses import dataclass, field
from kubecrd import schemabase
from apischema import schema
from kr8s.asyncio.objects import APIObject


@dataclass()
class MyCustomResourceDefinition(schemabase.KubeResourceBase):
    __group__ = "example.com"
    __version__ = "v1"

    foo: str
    bar: str
    baz: list[str] = field(
        default_factory=list,
        metadata=schema(
            description="List of baz",
            unique=False,
        ),
    )


class MyCustomResourceObject(APIObject):
    version = f"{MyCustomResourceDefinition.__group__}/{MyCustomResourceDefinition.__version__}"
    kind = MyCustomResourceDefinition.__name__.lower()
    singular = MyCustomResourceDefinition.singular()
    plural = MyCustomResourceDefinition.plural()
    endpoint = MyCustomResourceDefinition.plural()
    namespaced = True

I wonder if there is anything we could do in kr8s to make this more seamless?

Tasks

Beta Give feedback

1. Create an instance of CustomResourceDefinition from a dataclass #456
   enhancement kr8s +2
2. Create an APIObject based class from a CustomResourceDefinition #457
   enhancement kr8s +2

[jacobtomlinson]

I spent some time thinking about this today.

Firstly it looks like kubecrd is unmaintained, there has been no activity on the project for a couple of years and issues/PRs are not being responded to. Also looking into the code it seems pretty lightweight and most of the work is being done by apischema to convert the dataclass to an OpenAPI schema.

Thinking about the core goal here there seem to be two things we want to achieve:

• Define a Custom Resource Definition version spec in Python as a dataclass and create/update/delete the CRD.
• Create a kr8s object class based on APIObject to enable creating/updating/deleting of those Custom Resources

Thinking about it this way this could be achieved in two independent stages so I'm going to open to separate issues to track each one.