Unwanted custom resource object merging on redeploy occurs

[ghost]

Bug exercise:

1. Deploy some CRD into cluster: kubectl -f https://github.com/zalando/postgres-operator/blob/master/manifests/operatorconfiguration.crd.yaml.
2. Deploy some CRD defined object with k8s-handle: operatorconfigurations.acid.zalan.do where .configuration.kubernetes.custom_pod_annotations: { "keya": "valuea" } has defined.
3. Redeploy current object with fixed section .configuration.kubernetes.custom_pod_annotations: { "keyb": "valueb" }.

The old and new custom_pod_annotations will be merged at result, but 2020-01-09 06:15:39 INFO:k8s_handle.k8s.provisioner:OperatorConfiguration "zalando-postgres-operator" already exists, replace it be logged. (replace != merge)

kubectl -n kube-system get operatorconfigurations.acid.zalan.do zalando-postgres-operator -o jsonpath={.configuration.kubernetes.custom_pod_annotations}
map[keya:valuea keyb:valueb]

[rvadim]

Hi, thank you for report.
@furiousassault I think we should add warning about labels and/or annotations like have with Service ports. Do you have another suggestions? Can we process labels/annotations and similar lists with replace strategy instead of merge?

[furiousassault]

Good day. The problem is k8s-handle has predefined, generalized behavior with the resources of different kinds: like, "if it's not present, create it, else replace (or merge)".
For the resources of specific kinds, it performs additional implicit spec mutations, like "ports" in implementation of replacing services, and others.

I don't know at this moment, whether we can (and should) analyze CRD object and replace its parts while merging in general, as we do with services: POC needed, not to say it's not quite clean.

As a more clean solution, we could try to see if we can develop an user-defined "strategies" of some sort, to let user choose, what to do with a resource if it possible, patch or replace. In a config.yaml / CLI / Env parameter.
That seems it would be good solution, but requires a bigger effort and discussion.