Surface ALB information into rollout status

[jessesuen]

Summary

The recent ALB weight verification feature allowed Argo Rollouts to discover information about the underlying AWS LoadBalancer and TargetGroups, including ARN, IDs, tags, etc... Currently this is only used for verifying the weights of the TargetGroup, but it is not used anywhere else. For debugging and analysis purposes, it would be useful to surface the ALB and target group information in the rollout status. Like so:

status:
  alb:
    loadBalancer:
      name: k8s-devdeplo-testdele-b9061572ad
      arn: arn:aws:elasticloadbalancing:us-west-2:1234567891011:loadbalancer/app/k8s-devdeplo-testdele-abcdef1234/3a47c96b75571d0e
    canaryTargetGroup:
      name: k8s-devdeplo-testdele-ab72c5b132
      arn: arn:aws:elasticloadbalancing:us-west-2:1234567891011:targetgroup/k8s-devdeplo-testdele-ab72c5b132/df2957821c1214fc
    stableTargetGroup:
      name: k8s-devdeplo-testdele-8832d6519a
      arn: arn:aws:elasticloadbalancing:us-west-2:1234567891011:targetgroup/k8s-devdeplo-testdele-8832d6519a/df2957821c1214fc 

Use Cases

When would you use this?

In order to query AWS CloudWatch for metrics about a canary service, we need to know the canary TargetGroup. However, the target group name is not easily known to the user. By filling in the target group information under the rollout status, it would allow users to perform queries about metrics specific to the canary target group by passing the target group name to the cloudwatch query

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[noam-codefresh]

If I understand correctly, the alb traffic routing can be applied to BlueGreen as well. Am I correct?
If so - do you want the status.alb to include CanaryTargetGroup and StableTargetGroup? Or do you expect it to use ActiveTargetGroup and PreviewTargetGroup?

[noam-codefresh]

I just created a PR - #1625

[alexmt]

Implemented by #1625 . Thank you @noam-codefresh !

[danil-smirnov]

Hey, it seems this works only if --aws-verify-target-group parameter is passed to the controller. I'd expect this to work always if trafficRouting.alb is used in the rollout