Rollout is not dynamic labels aware

[kandeshvari]

Summary

I use dynamic labeling to pass traffic to leader pod. Definition is

apiVersion: v1
kind: Service
metadata:
    name: xxx
spec:
    ports:
        -   name: xxx
            port: 8080
            protocol: TCP
            targetPort: 8080
    selector:
        app: xxx
        role: leader

Label role: leader is added to pod by a sidecar container after a complex leader check.

I do not use label role in Rollout and get this error

status:
  conditions:
  - lastTransitionTime: "2021-11-14T16:13:51Z"
    lastUpdateTime: "2021-11-14T16:13:51Z"
    message: 'The Rollout "xxx" is invalid: spec.strategy.canary.stableService:
      Invalid value: "xxx": Service "xxx" has unmatch
      lable "role" in rollout'
    reason: InvalidSpec

Is there possibility to use argo rollout in such cases?

argo rollouts: master from 13 Nov '21 k8s: 1.22.3

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[huikang]

@kandeshvari , if the match label is added to the pod template as well, I think it should work. Could you verify if the pod label matches the service label?

[kandeshvari]

@huikang, if I set role: foo it doesn't work - error is the same. If I set role: leader - all works fine. But it is not a behaviour that I need. I want to set role: leader dynamically. Only one pod can be leader, but if I set role: leader in the Rollout - all the pods have this label. It is wrong.

[huikang]

The rollout's podTemplate likes Deployment, where all pods have the same labels. The behavior you described sounds a statefulset.

So I don't think dynamic labels will be supported for rollout CR.

[kandeshvari]

Dynamic labels are not for Rollout. They are for Pod. As I understand - Rollout cr is an extension of a Deployment and must act as a Deployment. If I use plain Deployment - everything works fine, if I "translate" it to Rollout - I'm getting the error. So, I may conclude - the problem is in the Rollout cr and excessive label checks, that are not present in the Deployment.

[huikang]

The rollout controller checks if the service's label matches the pods label

apiVersion: v1
kind: Service
metadata:
    name: xxx
spec:
    selector:
        L1: K1
        L2: K2

Then the rollout must have labels L1: K1 and L2: K2 in the its selector's label.

piVersion: argoproj.io/v1alpha1
kind: Rollout
metadata:
  name: rollouts-test
spec:
  selector:
    matchLabels:
        L1: K1    # --------- > match service's label
        L2: K2  

Could you illustrate what you use cases?

[kandeshvari]

My case

                                          ┌───────────────┐
                                          │Pod (active)   │
              ┌──────────────────────────►│               │
              │                           │ labels:       │
┌─────────────┴──┐                        │   role: leader│
│Service         │                        └───────────────┘
│                │
│  selector:     │
│    role: leader│
└────────────────┘                        ┌───────────────┐
                                          │Pod (standby)  │
                                          │               │
                                          │ labels: []    │
                                          └───────────────┘

role: leader is a dynamically added to Pod label. Service is always static and points to active pod.

I want to use canary deployment without any traffic shaper. So I await that argo rollouts just will create separate deployment for me, which in my case will be one more standby pod. I will test it manually, switch the leader to this node, and promote it to complete the deployment.

[huikang]

Looks like rollout is missing in the picture. Are the two pods belong to the same rollout? What is the selector label of the rollout?

[odorT]

I also have the same problem. Are there any workarounds?

[github-actions[bot]]

This issue is stale because it has been open 60 days with no activity.