Changing Pod labels with Kubernetes Go client

[Igor Shmukler]

Hello,

I am trying to understand something about v1beta2 Go client API. Sorry, but I am new to Kubernetes. Please help me out. It says:

// Label selector for pods. Existing ReplicaSets whose pods are
// selected by this will be the ones affected by this deployment.
// It must match the pod template's labels.
Selector *metav1.LabelSelector `json:"selector" protobuf:"bytes,2,opt,name=selector"`

I have a "custom" label, say color that I want to change from blue or green to solve my CD/CI task. From CLI, I can pass --overwrite and kubectl changes the label's value just fine.

When I am trying to use the API to change just the labels, it returns: the "selector does not match template labels" error. What do I need to do for the label change to succeed? How to I make it "match the template?"

I also see https://github.com/kubernetes/kubernetes/pull/50719 and the selector is now immutable. If selector has to match the labels and selector is immutable, how do I change the labels, now?

Right now, it is either the error: `failed to update deployment: Deployment.apps ...  field is immutable` when I try to change both `MatchLabels` and `Labels` or ``selector` does not match template `labels``.

What do I need to do for the label to get changed/patched?

Thank you

[Brian Grant]

Moved to kubernetes-users

kubernetes-dev to bcc

Thanks for also posting to stackoverflow:

https://stackoverflow.com/questions/51437725/k8s-v1beta2-deploymentspec-labelselector-interpretation

Though I'll answer here so that I can link to other sources, and point out some places/ways to search for info in the future.

Looking at documentation on kubernetes.io, it looks like selector immutability was noted in the Deployment documentation:

https://kubernetes.io/docs/concepts/workloads/controllers/deployment/#updating-a-deployment

But not in the ReplicaSet documentation:

https://kubernetes.io/docs/concepts/workloads/controllers/replicaset/

If you'd like to help by adding a note similar to the one for Deployment, the documentation is in https://github.com/kubernetes/website/tree/master/content/en/docs/concepts/workloads/controllers

and the contributor guide is here: https://github.com/kubernetes/community/tree/master/contributors/guide

However, it sounds like you want to do a blue/green deployment. If you search for "how to do a blue green deployment kubernetes", you should get many relevant hits, such as:

https://www.ianlewis.org/en/bluegreen-deployments-kubernetes 

https://medium.com/@jrhouston/orchestrating-blue-green-deployments-with-kubernetes-cb3632d19f87

https://www.coursera.org/lecture/google-kubernetes-engine/canary-and-blue-green-deployments-ADFs4

https://container-solutions.com/kubernetes-deployment-strategies/

and several others

which change the service selector instead of controller selectors.

A number of deployment tools, such as Spinnaker, can also do this for you.

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