Challenge - Istio

Write traffic routing with a VirtualService.

Challenge: a canary release

In this challenge you'll roll out the new version of the api service gradually with Istio. There are two deployments: labelled version: v1 and version: v2. The goal:

90% of traffic   -> v1
10% of traffic   -> v2
requests with the "x-test: evet" header -> always v2

First you'll define the subsets with a DestinationRule, then write the routing with a VirtualService.

Exercise DestinationRule

Write a DestinationRule YAML: networking.istio.io/v1; name api; host: api; under subsets, name: v1 (labels: version: v1) and name: v2 (labels: version: v2).

Show example solution

apiVersion: networking.istio.io/v1
kind: DestinationRule
metadata:
  name: api
spec:
  host: api
  subsets:
    - name: v1
      labels:
        version: v1
    - name: v2
      labels:
        version: v2

Exercise VirtualService

Write a VirtualService's http section (starting with http:): the first rule sends requests with headers: x-test: exact: evet under match to host: api, subset: v2; the second rule, with route, gives weight: 90 to v1 and weight: 10 to v2.

Show example solution

http:
  - match:
      - headers:
          x-test:
            exact: evet
    route:
      - destination:
          host: api
          subset: v2
  - route:
      - destination:
          host: api
          subset: v1
        weight: 90
      - destination:
          host: api
          subset: v2
        weight: 10

Test yourself

Should the header rule be written before the weighted rule in the VirtualService?
- The weighted rule always comes first
- They can't be in the same rule
- Yes; http rules are tried in order, the first match applies
- No; order doesn't matter
Show answer

Yes; http rules are tried in order, the first match applies — The weighted rule catches every request since it has no match condition.

Write the label selecting the subset.

  subsets:
    - name: v2
      labels:
        ____: v2

Show answer

  subsets:
    - name: v2
      labels:
        version: v2

Match.

DestinationRule

Subsets
VirtualService

Routing
weight

Traffic share
match.headers

Select by header

Next lesson: Challenge - OPA

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