Canary Deployments with Istio

Canary Deployment is the process of rolling out a new version of an application to a small set of users, as a step to verify the absence of issues, and then with a higher assurance of quality release to the wider audience.

Let’s continue with the same buggy subset of sa-logic to demonstrate canary deployments, by boldly sending 20% of the users to the buggy version (this represents the canary deployment) and 80% to the healthy service by applying the VirtualService below:

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: sa-logic
spec:
  hosts:
    - sa-logic    
  http:
  - route: 
    - destination: 
        host: sa-logic
        subset: v1
      weight: 80         # 1
    - destination: 
        host: sa-logic
        subset: v2
      weight: 20         # 1

1. Weight specifies the percentage of requests to be forwarded to the destination or subset of the destination.

Update the previous sa-logic virtual service configuration using the following commands:

$ kubectl apply -f resource-manifests/istio/canary/sa-logic-subsets-canary-vs.yaml
virtualservice.networking.istio.io/sa-logic configured

We immediately see that some of our requests are failing:

$ while true; do \
    curl -i http://$EXTERNAL_IP/sentiment -H "Content-type: application/json" \
    -d '{"sentence": "I love yogobella"}' \
    --silent -w "Time: %{time_total}s \t Status: %{http_code}\n" -o /dev/null; \
    sleep .1; done
Time: 0.153075s          Status: 200
Time: 0.137581s          Status: 200
Time: 0.139345s          Status: 200
Time: 30.291806s         Status: 500

VirtualServices enable Canary Deployments and with this method, we reduced potential damages to 20% of our user base. Beautiful! Now we can use Shadowing and Canary Deployments every time we are insecure about our code, basically always 😜.