SetHeaderRoute not change VirtualService

[huoyinghao]

Discussed in #2776

^{Originally posted by huoyinghao May 12, 2023}
Hi, team

here is my rollout yaml ↓

---
apiVersion: argoproj.io/v1alpha1
kind: Rollout
metadata:
  annotations:
    rollout.argoproj.io/revision: "1"
    rollout.argoproj.io/workload-generation: "20"
  creationTimestamp: "2023-05-12T11:07:57Z"
  generation: 1
  name: test-rollout-150
  namespace: test-rollout
  resourceVersion: "23904088"
  uid: db29e57b-c939-41c0-bf8c-53b9fe38f06f
spec:
  replicas: 1
  strategy:
    canary:
      steps:
      - setCanaryScale:
          replicas: 1
      - setHeaderRoute:
          match:
          - headerName: header1
            headerValue:
              prefix: test1
          - headerName: header2
            headerValue:
              prefix: test2
          name: route-1
      - pause: {}
      trafficRouting:
        istio:
          destinationRule:
            canarySubsetName: canary
            name: test-rollout-150
            stableSubsetName: stable
          virtualService:
            name: test-rollout-150
            routes:
            - primary
        managedRoutes:
        - name: route-1
---
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  creationTimestamp: "2023-05-12T08:44:58Z"
  generation: 14
  name: test-yaml-rollout
  namespace: test-rollout
  ownerReferences:
  - apiVersion: apps/v1
    kind: Deployment
    name: test-yaml-rollout
    uid: dbc63044-3d9a-44a8-8618-aa63bc369c4f
  resourceVersion: "23881171"
  uid: 21351a56-123e-4ba5-9942-3194f073347c
spec:
  hosts:
  - test-yaml-rollout
  http:
  - name: primary
    route:
    - destination:
        host: test-yaml-rollout
        subset: stable
      weight: 100
    - destination:
        host: test-yaml-rollout
        subset: canary
      weight: 0
  

when i promote it,i think VirtualService should be changed

but the fact doesn t seem like that, afterwards i went to check the relevant code,i found the code to set the header route.

		// We need to check for Generation > 1 because when we first install the rollout we run step 0 this prevents that.
		// We could also probably use c.newRS == nil || c.newRS.Status.AvailableReplicas == 0
		if currentStep != nil && c.rollout.ObjectMeta.Generation > 1 {
			if currentStep.SetHeaderRoute != nil {
				if err = reconciler.SetHeaderRoute(currentStep.SetHeaderRoute); err != nil {
					return err
				}
			}
			if currentStep.SetMirrorRoute != nil {
				if err = reconciler.SetMirrorRoute(currentStep.SetMirrorRoute); err != nil {
					return err
				}
			}
		}

It seems that the controller will check if the rollout generation > 1 then updates vs routing policies, which means if we want the setHeaderRoute step work we have to update rollout, either by edit manually or an unwanted promote. (Is there any other ways to increase the generation?)

I don't understand why we add the restriction here. Or maybe I using it incorrectly? Any advice is apperaciate.

(the above comes from translation software)

Can you help me solve this problem? Thank you very much.

[danielsantosdfs13]

I also have this problem 👍

[zm1990s]

First I want to thank you for the yaml example, it really saves a lot of time.
From my experience, the first rollout will only deploy stable version of Pods, and it is only after updating the image tag that canary Pods start to appear, then the header-based forwarding policy takes effect.
So it is normal for the first rollout not to change the header-based policy because the canary is empty.