Challenge - Istio
- Docker & Kubernetes course
- Expert
- Lesson 45/47
- 5 min
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 v2First you'll define the subsets with a DestinationRule, then write the routing with a VirtualService.
Practice 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).
Starter code
# buraya yazSample solution
apiVersion: networking.istio.io/v1
kind: DestinationRule
metadata:
name: api
spec:
host: api
subsets:
- name: v1
labels:
version: v1
- name: v2
labels:
version: v2Expected output
destinationrule.networking.istio.io/api created
Practice 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.
Starter code
# buraya yazSample 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: 10Expected output
virtualservice.networking.istio.io/api configured
$ for i in $(seq 100); do curl -s http://api/surum; done | sort | uniq -c
91 v1
9 v2
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 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 Correct answer
- No; order doesn't matter
Explanation: The weighted rule catches every request since it has no match condition.
2 Write the label selecting the subset.
subsets:
- name: v2
labels:
____: v2 subsets:
- name: v2
labels:
version: v2Explanation: A subset is defined by pod labels.
3 Match.
| Term | Meaning |
|---|---|
DestinationRule |
Subsets |
VirtualService |
Routing |
weight |
Traffic share |
match.headers |
Select by header |