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Specify service port in TrafficSplit #14

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stefanprodan opened this issue Apr 30, 2019 · 3 comments · Fixed by #15
Closed

Specify service port in TrafficSplit #14

stefanprodan opened this issue Apr 30, 2019 · 3 comments · Fixed by #15

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@stefanprodan
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A Kubernetes service can expose more than one port. To support such a service the TrafficSplit could have an optional field in the backend spec:

ClusterIP with multiple ports:

apiVersion: v1
kind: Service
metadata:
  name: frontend-primary
spec:
  type: ClusterIP
  selector:
    app: frontend-primary
  ports:
    - name: http
      port: 8080
      protocol: TCP
      targetPort: http
    - name: grpc
      port: 9090
      protocol: TCP
      targetPort: grpc

TrafficSplit for HTTP:

apiVersion: v1beta1
kind: TrafficSplit
metadata:
  name: frontend
spec:
  service: frontend
  backends:
  - service: frontend-primary
    port: 8080
    weight: 900m
  - service: frontend-canary
    port: 8080
    weight: 100m
@nicholasjackson
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Hey @stefanprodan not sure how Istio configures things, just grokking the docs, but wondering if this information should not be obtained from service discovery. The service in question would be an Envoy proxy, not a kubernetes service.

@stefanprodan
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Both Istio and App Mesh rely on ClusterIPs to define backends:

Istio:

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: frontend
  namespace: test
spec:
  hosts:
    - frontend
  http:
    route:
    - destination:
        host: frontend-primary
        port:
          number: 9898
      weight: 100
    - destination:
        host: frontend-canary
        port:
          number: 9898
      weight: 0

App Mesh:

apiVersion: appmesh.k8s.aws/v1alpha1
kind: VirtualNode
metadata:
  name: frontend
  namespace: test
spec:
  meshName: global.appmesh-system
  listeners:
    - portMapping:
        port: 9898
        protocol: http
  serviceDiscovery:
    dns:
      hostName: frontend.test
  backends:
    - virtualService:
        virtualServiceName: backend.test
---
apiVersion: appmesh.k8s.aws/v1alpha1
kind: VirtualService
metadata:
  name: frontend.test
  namespace: test
spec:
  meshName: global.appmesh-system
  virtualRouter:
    name: frontend-router
  routes:
    - name: frontend-route
      http:
        match:
          prefix: /
        action:
          weightedTargets:
            - virtualNodeName: frontend
              weight: 100

@grampelberg grampelberg mentioned this issue Apr 30, 2019
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@nicholasjackson
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Thanks, just been looking at the Istio docs, did not realize you could have multiple destinations ports for a data plane.

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Add explanation for why ports are on Services instead of TrafficSplit servicemeshinterface/smi-spec
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@nicholasjackson @stefanprodan