5. Load Balancing

TrafficPolicy

• You can modify the trafficPolicy of Destination Rule to make sticky session.

  apiVersion: networking.istio.io/v1alpha3
  kind: DestinationRule
  metadata:
  name: my_web
  spec:
  host: my_web.staging.svc.cluster.local
  trafficPolicy:
    loadBalancer:
     consistentHash:
        useSourceIp: true
  

• Load balancer
  • Typically algorithm: round robin (輪詢)
  • Consistent hashing:
    • Source IP -> Hash
    • You do some heavy processing for a user, and you want to cache that in the pod’s memory so the next time the same client requests, they get a cache hit. Don’t ever rely on this to implement a “session”.
  • You can use:
    • httpHeaderName: you need to make sure the header will be propagated during the whole Jeager trace.
    • httpCookie
    • useSourceIp
    • minimumRingSize
• But if you want to use it with weighting routing, it does not work.