Apply all labels that klusterlet has to all the resources it will create and keep labels in sync

[EricaJ6]

Describe the enhancement
We observed that resources created by klusterlet do not have labels that klusterlet has. For example, klusterlet-agent in the open-cluster-management-agent namespace is missing labels. We’re using these labels for cost tracking purposes. As discussed with @qiujian16, and agreed to apply all labels that klusterlet has to all the resources it will create. Additionally, if labels on the klusterlet got changed (either updated or added new ones), all the resources created by it should be in sync as well.

[qiujian16]

@zhiweiyin318 will you be able to take a look at this one?

[zhiweiyin318]

@EricaJ6 @qiujian16 I have some questions about this requirement.

1. just double check that we need to sync the label to the all agent resources or only deployments since the description mentioned cost tracking purposes.
2. do we need delete the label from the agent if it is removed from the klusterlet ? the reason why I ask is currently the map update strategy is merge.

[EricaJ6]

Thanks @zhiweiyin318! For your questions,

1. We should sync the labels to all resources created by the klusterlet. The goal is all resources should have the necessary labels. I looked into the above PR, it looks like currently, only deployments have labels added, could you please add labels to all resources (such as spec. template. metadata.labels and so on)?
2. If the label got removed from the klusterlet, it should also be removed from all resources created by the klusterlet.

[zhiweiyin318]

@EricaJ6 currently there are 2 labels app: klusterlet-agent and createdBy: klusterlet on the deployment created by klusterlet.
if we add the 2 labels to all agent resources, not sure if can meet your requirements for cost tracking purpose?
if the 2 labels can meet your requirements, I think it is not necessary to sync labels from klusterlet.

[EricaJ6]

@zhiweiyin318 Other than the 2 default labels, we are adding additional customization labels to klusterlet, and the organization is using these customized labels for cost-tracking purpose. That's why we would like to sync the labels to all resources created by the klusterlet. Because of the use of additional customization labels, the 2 default labels do not meet the requirements.

[zhiweiyin318]

@EricaJ6 I synced the labels to all agent resources in the PR, but currently we cannot remove the label from agent resouces after the label is deleted on the klusterlet. Because we use the apply function in the openshift/library-go lib to apply resources, and it uses merge to handle labels and annotations.

ocm/vendor/github.com/openshift/library-go/pkg/operator/resource/resourcemerge/object_merger.go

Line 16 in 3001883

MergeMap(modified, &existing.Labels, required.Labels)

ocm/vendor/github.com/openshift/library-go/pkg/operator/resource/resourcemerge/object_merger.go

Line 141 in 3001883

func MergeMap(modified *bool, existing *map[string]string, required map[string]string) {

so if want to delete the removed labels on the agent resources , need to remove it from the agent resources manually .

[EricaJ6]

Thanks @zhiweiyin318 on sharing the information and updating the PR!

1. To make sure all pods created by the deployments also have the labels, how about adding labels to the spec.template.metadata.labels of the *deployment.yaml files as well?
2. Will clusteradm repo also needs to be updated for synced labels to take effect?

[zhiweiyin318]

@EricaJ6

1. Added labels for pods.
2. I don't think clusteradm repo need to be updated since the latest image will take affect after the PR is merged. you can add labels to klusterlet after the cluster is joined to the hub.

[EricaJ6]

@zhiweiyin318

1. The pods' labels look good!
2. Is there a timeline for when the PR will be released? We'll try it out.

[zhiweiyin318]

the feature will be included into release v0.14.0. you can try it using the latest images after the PR is merged.

[zhiweiyin318]

@EricaJ6 The PR is merged. please use the latest images to take a try.

[EricaJ6]

Thanks @zhiweiyin318 for the updates! I will try it once it is released.