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A/B Testing and Canary Deployments

Canary Deployment and A/B testing with Ambassador's Envoy API Gateway.

canary

Deploy Ambassador

Deploy Ambassador and expose it with a LoadBalancer service or NodePort if you are running on-prem:

helm repo add sp https://stefanprodan.github.io/k8s-podinfo

helm upgrade --install --wait envoy \
    --set service.type=LoadBalancer \
    --set replicaCount=2 \
    sp/ambassador

Find the the LoadBalancer IP and store it in an environment variable for later use:

export ENVOY=$(kubectl get svc --namespace default envoy-ambassador -o jsonpath='{.status.loadBalancer.ingress[0].ip}')

Test that Envoy is listening on port 80:

curl -sI http://$ENVOY | grep envoy
server: envoy

Expose services via the API gateway

Deploy podinfo version 0.1.0 as the general available release:

kubectl apply -f ./deploy/canary/ga-dep.yaml

Expose the GA release via Ambassador on the podinfo.test domain:

apiVersion: v1
kind: Service
metadata:
  name: ga-podinfo
  annotations:
    getambassador.io/config: |
      ---
      apiVersion: ambassador/v0
      kind: Mapping
      name: ga-podinfo
      prefix: /
      host: podinfo.test
      service: ga-podinfo.default:9898
spec:
  type: ClusterIP
  ports:
    - port: 9898
      targetPort: 9898
      protocol: TCP
  selector:
    app: ga-podinfo

Apply the GA service:

kubectl apply -f ./deploy/canary/ga-svc.yaml

Test that v0.1.0 is available at podinfo.test with curl:

curl -H 'Host: podinfo.test' -sS http://$ENVOY/version | grep version
version: 0.1.0

Canary deployment

Let's assume you have an insiders program for your users and some of them enrolled. Once enrolled your users requests will have a HTTP header like X-User: insider attached to every request.

Simulate an insider user call with:

curl -H 'X-User: insider' -H 'Host: podinfo.test' -sS http://$ENVOY/version | grep version
version: 0.1.0

Deploy podinfo version 0.2.0 as a release candidate:

kubectl apply -f ./deploy/canary/canarya-dep.yaml

Create a service named canarya-podinfo and instruct Ambassador to shift the insiders to the RC deployment:

apiVersion: v1
kind: Service
metadata:
  name: canarya-podinfo
  annotations:
    getambassador.io/config: |
      ---
      apiVersion: ambassador/v0
      kind: Mapping
      name: canarya-podinfo
      prefix: /
      host: podinfo.test
      service: canarya-podinfo.default:9898
      headers:
        X-User: insider
spec:
  type: ClusterIP
  ports:
    - port: 9898
      targetPort: 9898
      protocol: TCP
  selector:
    app: canarya-podinfo

Apply the service with:

kubectl apply -f ./deploy/canary/canarya-svc.yaml

Now if a normal user calls podinfo nothing changed, but if an insider calls podinfo he/she will be routed to version 0.2.0:

curl -H 'Host: podinfo.test' -sS http://$ENVOY/version|grep version
version: 0.1.0

curl -H 'X-User: insider' -H 'Host: podinfo.test' -sS http://$ENVOY/version|grep version
version: 0.2.0

A/B testing

Let's assume you have a new release candidate version that you want to test on a small subset of your insiders.

Deploy podinfo version 0.2.1 as a release candidate:

kubectl apply -f ./deploy/canary/canaryb-dep.yaml

Create a service named canaryb-podinfo and instruct Ambassador to shift ten percent of the insiders traffic to v0.2.1:

apiVersion: v1
kind: Service
metadata:
  name: canaryb-podinfo
  annotations:
    getambassador.io/config: |
      ---
      apiVersion: ambassador/v0
      kind: Mapping
      name: canaryb-podinfo
      prefix: /
      host: podinfo.test
      service: canaryb-podinfo.default:9898
      weight: 10
      headers:
        X-User: insider
spec:
  type: ClusterIP
  ports:
    - port: 9898
      targetPort: 9898
      protocol: TCP
  selector:
    app: canaryb-podinfo

Apply the service with:

kubectl apply -f ./deploy/canary/canaryb-svc.yaml

Now let's call the service in a while loop, one in ten calls will be routed to v0.2.1:

while true; do sleep 1; curl -H 'X-User: insider' -H 'Host: podinfo.test' -sS http://$ENVOY/version|grep version; done
version: 0.2.0
version: 0.2.0
version: 0.2.0
version: 0.2.0
version: 0.2.0
version: 0.2.0
version: 0.2.0
version: 0.2.0
version: 0.2.0
version: 0.2.1

CI/CD Automation

Once you have in place the GA and Canary releases you would probably want to automate the deployment of patches for 0.1.x and 0.2.x.

Continuous delivery can be accomplished with a GitOps pipeline that involves several tools like TravisCI and Weave Flux.

Weave Flux

GA GitOps pipeline steps:

  • An engineer cuts a new release by tagging the master branch as 0.1.1
  • GitHub notifies TravisCI that a new tag has been committed
  • TravisCI builds the Docker image, tags it as 0.1.1 and pushes it to Docker Hub
  • Weave Flux detects the new tag on Docker Hub and updates the GA deployment definition
  • Weave Flux commits the GA deployment definition to GitHub
  • Weave Flux triggers a rolling update of the GA deployment

The canary continuous delivery follows the same pattern, the only difference is that Weave Flux must be configured with a different filter:

  • 0.1.* for GA
  • 0.2.* for Canary

Monitoring

Install Grafana chart with Weave Cloud data source:

helm install --name weave \
 --set service.type=LoadBalancer \
 --set token=WEAVE-CLOUD-TOKEN \
 sp/grafana

Start a load test for both GA and Canary deployments:

# GA
hey -n 10000 -host podinfo.test http://$ENVOY

# Canary
hey -n 10000 -host podinfo.test -H 'X-Client: insider' http://$ENVOY

Open Grafana's URL and navigate to Ambassador dashboard:

Ambassador metrics

TODO: GA vs Canary RED metrics dashboard