Add support for several servicePorts per ingress using canary via alb plugin

[andreosipov]

Summary

At this moment argo rollouts spec with alb plugin supports several ingresses, but doesn't support several ports for k8s services. This is a problem, because there are lots of use cases when k8s service has several ports:

Use Cases

In our setup we have several ingresses pointed at the same load balancer via alb.ingress.kubernetes.io/group.name annotation and each ingress has an underlying k8s service with a specific port (k8s service is the same for the business service), example:

ingress №1:

rules:
    - host: api-internal.example.net
      http:
        paths:
          - path: /*
            pathType: ImplementationSpecific
            backend:
              service:
                name: svc-stable
                port:
                  name: http-svc-internal

ingress №2:

rules:
    - host: api-specific.example.net
      http:
        paths:
          - path: /*
            pathType: ImplementationSpecific
            backend:
              service:
                name: svc-stable
                port:
                  name: http-svc-specific

Given the fact that the rollout spec should include all ingresses for the application and in case you have several ports being listened there is a problem with canary:

spec:
  strategy:
    canary:
      canaryService: svc-canary
      stableService: svc-stable
      maxUnavailable: '0%'
      maxSurge: '10%'
      trafficRouting:
        alb:
          ingresses:
            - internal-api
            - specific-api
          servicePort: http-svc-specific OR http-svc-internal 

It would be nice to add support for service ports per each ingress so canary could be used for all of them.

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[rohitgit-web]

i have also same use case for internal and external ALB's on same rollout. It would be nice to add support for service ports per each ingress so canary could be used for all of them.