Traffic management

Istio manages traffic with two objects: a DestinationRule defines a service's subsets (e.g. versions) and connection settings; a VirtualService determines which subset requests go to and in what proportion. For a canary deployment, the new version gets a small percentage of the traffic:

apiVersion: networking.istio.io/v1
kind: DestinationRule
metadata:
  name: api
spec:
  host: api
  subsets:
    - name: v1
      labels: {surum: v1}
    - name: v2
      labels: {surum: v2}
---
apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: api
spec:
  hosts: [api]
  http:
    - route:
        - destination: {host: api, subset: v1}
          weight: 90
        - destination: {host: api, subset: v2}
          weight: 10

The VirtualService defines retries and timeouts; the DestinationRule defines circuit breaking (taking an instance returning too many errors out of rotation for a while):

# VirtualService
  http:
    - route: [{destination: {host: api, subset: v1}}]
      timeout: 3s
      retries:
        attempts: 3
        perTryTimeout: 1s
        retryOn: 5xx,reset,connect-failure
# DestinationRule
  trafficPolicy:
    outlierDetection:
      consecutive5xxErrors: 5
      interval: 30s
      baseEjectionTime: 60s