Progressive rollout with istio subsets

[msonnleitner]

Summary

Is it possible or useful to do automated canary rollouts based on subsets? Given the following rollout, I was wondering, if there is any particular reason, that two services are required. Would it not be possible to use one service and two Istio subsets (like v1,v2)

apiVersion: argoproj.io/v1alpha1
kind: Rollout
metadata:
  name: rollout-example
spec:
  ...
  strategy:
    canary:
      steps:
      - setWeight: 5
      - pause:
          duration: 10m
      canaryService: canary-svc # required
      stableService: stable-svc  # required
      trafficRouting:
        istio:
           virtualService: 
            name: rollout-vsvc  # required
            routes:
            - primary # At least one route is required?

Could it not potentially done like that?

  strategy:
    canary:
      steps:
      - setWeight: 5
      - pause:
          duration: 10m
      service: svc  # required
      canarySubset: v2 # required
      stableSubset: v1  # required
      trafficRouting:
        istio:
           virtualService: 
            name: rollout-vsvc  # required
            routes:
            - primary # At least one route is required?

Motivation

Apart from the question, if two services or two subsets are a better approach:

In Anthos service mesh, there is a (beta) dashboard for traffic splits which provides nice metrics for different versions of a service, providing visibility for different versions of services. For two different services, this would not work.

[jessesuen]

This is something we want to do. #617 is tracking the feature request.