Retry Logic

Microservices architectures are distributed. This means more requests on the network, increasing the chance of transient failures like network congestion.

Adding retry policies for requests helps build resiliency in a services architecture. Often, this retry logic is built into source code. But with Istio, you can define retry policies with a traffic rule, offloading this logic to your services’ sidecar proxies. This can help you standardize around the same policies across many services, protocols, and programming languages.

In this example, all inbound requests to the helloworld service try 5 times, and an attempt is marked as failed if it takes longer than 2 seconds to complete.

apiVersion: networking.istio.io/v1alpha3
kind: DestinationRule
metadata:
  name: helloworld
spec:
  host: helloworld
  subsets:
  - name: v1
    labels:
      version: v1

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: helloworld
spec:
  hosts:
  - helloworld
  http:
  - route:
    - destination:
        host: helloworld
        subset: v1
    retries:
      attempts: 5
      perTryTimeout: 2s