Kafka Topic migration from one namespace to another

[drundusvit]

Hello.
We were about to deploy aiven kubernetes controller to monitor KafkaTopic resource creation across all namespaces in the cluster.
The idea for teams to keep topics that they own in their namespaces.
However, we've came up with a case which happens rather often in our org and prevents us from using the operator this way.
The case is: we won't be able to transfer a KafkaTopic definition from one namespace to another without deleting it? Even if I have this topic defined in multiple namespaces, removing it from one forces operator to remove it for good on aiven side. Is that correct assumption?
Is there a feature or a process on how to do the migration safely?
Thank you for the product!

[byashimov]

Hello!
There is an annotation you can use:

controllers.aiven.io/deletion-policy: Orphan

This skips the delation handler. Please try this on a test topic to make sure it works for you as expected.

We will update our docs with this example, thanks for reminding :)

[drundusvit]

Thank you! We'll try that!

[drundusvit]

I tried the annotation. I think it works as expected. However, I have a note how the process is visible from operator perspective:

1. When I added controllers.aiven.io/deletion-policy: Orphan annotation, operator didn't react much:

2025-09-22T11:06:36Z	INFO	controllers.KafkaTopic	setting up aiven client with instance secret	{"kind": "kafkatopic", "name": "aiven-operator-playground/playground-test-create-both-clusters", "annotations": {"controllers.aiven.io/generation-was-processed":"1","controllers.aiven.io/instance-is-running":"true"}}

I think this action needs an explicit confirmation that kafka recognises the resource as Orphaned. The reason for it is if the annotation process is silent, then we don't know if it was accepted by the operator. Imagine having a mistype in annotation and removing a topic...
2. When I removed the topic from the kubernetes cluster, the operator reacted as usual(scaring me):

2025-09-22T11:11:46Z	INFO	controllers.KafkaTopic	setting up aiven client with instance secret	{"kind": "kafkatopic", "name": "aiven-operator-playground/playground-test-create-both-clusters", "annotations": {"controllers.aiven.io/generation-was-processed":"1","controllers.aiven.io/instance-is-running":"true"}}
2025-09-22T11:11:46Z	INFO	controllers.KafkaTopic	instance was successfully deleted at aiven, removing finalizer	{"kind": "kafkatopic", "name": "aiven-operator-playground/playground-test-create-both-clusters", "annotations": {"controllers.aiven.io/generation-was-processed":"1","controllers.aiven.io/instance-is-running":"true"}}
2025-09-22T11:11:46Z	DEBUG	events	trying to delete instance at aiven	{"type": "Normal", "object": {"kind":"KafkaTopic","namespace":"aiven-operator-playground","name":"playground-test-create-both-clusters","uid":"8aa3f61e-02dc-43e1-ab82-3ecb010180e0","apiVersion":"aiven.io/v1alpha1","resourceVersion":"590067923"}, "reason": "TryingToDeleteAtAiven"}
2025-09-22T11:11:46Z	DEBUG	events	instance is gone at aiven now	{"type": "Normal", "object": {"kind":"KafkaTopic","namespace":"aiven-operator-playground","name":"playground-test-create-both-clusters","uid":"8aa3f61e-02dc-43e1-ab82-3ecb010180e0","apiVersion":"aiven.io/v1alpha1","resourceVersion":"590067923"}, "reason": "SuccessfullyDeletedAtAiven"}
2025-09-22T11:11:46Z	INFO	controllers.KafkaTopic	finalizer was removed, instance is deleted	{"kind": "kafkatopic", "name": "aiven-operator-playground/playground-test-create-both-clusters", "annotations": {"controllers.aiven.io/generation-was-processed":"1","controllers.aiven.io/instance-is-running":"true"}}

it just said that it removed it. sounds scary. and untraceable during an investigation

[vmyroslav]

Thanks @drundusvit for the feedback. We'll look into it and try to improve it in the documentation and the logs as well.