04. Traffic Management

Canary Release

• Deploy a new version of a software component but only make that new image live for a percentage of the time.
• The working version is the one being used in most of the time.

k8s

• You can copy the old deployment and rename it to use Canary Release.

Istio

• It allow you to do Canary Release by Version Grouping & Weighted Routing without mdofiying any code:
  • Use version to do deploy different deployments.
  • Then click “Create Weighted Routing” to do Canary Release.
  • The request will be redirected to the new deployments randomly.
• Virtual Service
  • kubectl get vs
  • enables you to conigure custom routing rules to the service mesh.
  • In k8s, a service is for service discovery. It is to automatically manange DNS service.
  • In Istio, VirtulaService managed by Istio-pilot to overwirte the Envoy proxy configuration.

  • kind: VirtualService
    apiVersion: networking.istio.io/v1alpha3
    metadata:
      name: test # name of virtual service
      namespace: default # the namespace of target serviCe
    spec:
      hosts:
        - mytest-domain.default.svc.cluster.local // the service DNS (k8s service)name
      http:
        - route:
           - destination:
               host: mytest-domain.default.svc.cluster.local // the target DNS name
               subset: a
             weight: 20
           - destination:
               host: mytest-domain.default.svc.cluster.local // the target DNS name
               subset: b
             weight: 80
    

• Destination Rules
  • kubectl get dr

  • kind: DestinationRule # Define which pods shuold be part of each subsets
    apiVersion: networking.istio.io
    metadata:
      name: my-service
      namespace: default
    spec:
      host: my-service
      trafficPolicy:
      subsets:
        - labels: # selectors
            version: a
          name: a
        - labels:
            version: b
          name: b
    

  • A configuration for load balancer to a particular service.
• Kiali will validate your yaml, but you can only delete all traffic routing/