Add propagation_policy option to APIObject.delete() method

[gree-gorey]

Regarding hjacobs/kube-janitor#28

As it turned out, the issue was the following.
When you delete an object of apps/v1 version, its dependent objects are deleted. But when you delete an object of extensions/v1beta1, its dependent objects are orphaned. Here is the ref to docs about this behavior: https://kubernetes.io/docs/concepts/workloads/controllers/garbage-collection/#setting-the-cascading-deletion-policy

So, when do this:

import pykube
from helper import get_kube_api
from pykube.objects import NamespacedAPIObject

api = get_kube_api()

d = type("Deployment", (NamespacedAPIObject,), {
    'version': "extensions/v1beta1",  # <----- HERE
    'endpoint': "deployments",
    'kind': "Deployment"
})

first_deploy = list(d.objects(api, namespace="dev"))[0]

first_deploy.delete()

its dependent objects are orphaned.

If you change version to apps/v1 then everything is ok.

Now, Kubernetes API allow you to specify propagationPolicy with possible values “Orphan”, “Foreground”, or “Background”. Example:

$ curl -X DELETE localhost:8080/apis/apps/v1/namespaces/default/replicasets/my-repset \
-d '{"kind":"DeleteOptions","apiVersion":"v1","propagationPolicy":"Background"}' \
-H "Content-Type: application/json"

So, I added optional argument propagation_policy with default value None, so that if someone want to explicitly specify policy they can do that with this flag.

[hjacobs]

Thanks!

[hjacobs]

Added docs: https://pykube.readthedocs.io/en/latest/api/pykube.html#pykube.objects.APIObject.delete