Istio A/B Testing

Search…
Istio A/B Testing
This guide shows you how to automate A/B testing with Istio and Flagger.
Besides weighted routing, Flagger can be configured to route traffic to the canary based on HTTP match conditions. In an A/B testing scenario, you'll be using HTTP headers or cookies to target a certain segment of your users. This is particularly useful for frontend applications that require session affinity.
Flagger A/B Testing Stages
Prerequisites
Flagger requires a Kubernetes cluster v1.16 or newer and Istio v1.0 or newer.
Install Istio with telemetry support and Prometheus:
1
istioctl manifest install --set profile=default
2
​
3
kubectl apply -f https://raw.githubusercontent.com/istio/istio/release-1.8/samples/addons/prometheus.yaml
Copied!
Install Flagger in the istio-system namespace:
1
kubectl apply -k github.com/fluxcd/flagger//kustomize/istio
Copied!
Create an ingress gateway to expose the demo app outside of the mesh:
1
apiVersion: networking.istio.io/v1alpha3
2
kind: Gateway
3
metadata:
4
  name: public-gateway
5
  namespace: istio-system
6
spec:
7
  selector:
8
    istio: ingressgateway
9
  servers:
10
    - port:
11
        number: 80
12
        name: http
13
        protocol: HTTP
14
      hosts:
15
        - "*"
Copied!
Bootstrap
Create a test namespace with Istio sidecar injection enabled:
1
kubectl create ns test
2
kubectl label namespace test istio-injection=enabled
Copied!
Create a deployment and a horizontal pod autoscaler:
1
kubectl apply -k https://github.com/fluxcd/flagger//kustomize/podinfo?ref=main
Copied!
Deploy the load testing service to generate traffic during the canary analysis:
1
kubectl apply -k https://github.com/fluxcd/flagger//kustomize/tester?ref=main
Copied!
Create a canary custom resource (replace example.com with your own domain):
1
apiVersion: flagger.app/v1beta1
2
kind: Canary
3
metadata:
4
  name: podinfo
5
  namespace: test
6
spec:
7
  # deployment reference
8
  targetRef:
9
    apiVersion: apps/v1
10
    kind: Deployment
11
    name: podinfo
12
  # the maximum time in seconds for the canary deployment
13
  # to make progress before it is rollback (default 600s)
14
  progressDeadlineSeconds: 60
15
  # HPA reference (optional)
16
  autoscalerRef:
17
    apiVersion: autoscaling/v2beta2
18
    kind: HorizontalPodAutoscaler
19
    name: podinfo
20
  service:
21
    # container port
22
    port: 9898
23
    # Istio gateways (optional)
24
    gateways:
25
    - public-gateway.istio-system.svc.cluster.local
26
    # Istio virtual service host names (optional)
27
    hosts:
28
    - app.example.com
29
    # Istio traffic policy (optional)
30
    trafficPolicy:
31
      tls:
32
        # use ISTIO_MUTUAL when mTLS is enabled
33
        mode: DISABLE
34
  analysis:
35
    # schedule interval (default 60s)
36
    interval: 1m
37
    # total number of iterations
38
    iterations: 10
39
    # max number of failed iterations before rollback
40
    threshold: 2
41
    # canary match condition
42
    match:
43
      - headers:
44
          user-agent:
45
            regex: ".*Firefox.*"
46
      - headers:
47
          cookie:
48
            regex: "^(.*?;)?(type=insider)(;.*)?quot;
49
    metrics:
50
    - name: request-success-rate
51
      # minimum req success rate (non 5xx responses)
52
      # percentage (0-100)
53
      thresholdRange:
54
        min: 99
55
      interval: 1m
56
    - name: request-duration
57
      # maximum req duration P99
58
      # milliseconds
59
      thresholdRange:
60
        max: 500
61
      interval: 30s
62
    # generate traffic during analysis
63
    webhooks:
64
      - name: load-test
65
        url: http://flagger-loadtester.test/
66
        timeout: 15s
67
        metadata:
68
          cmd: "hey -z 1m -q 10 -c 2 -H 'Cookie: type=insider' http://podinfo.test:9898/"
Copied!
Note that when using Istio 1.5 you have to replace the request-duration with a metric template.
The above configuration will run an analysis for ten minutes targeting Firefox users and those that have an insider cookie.
Save the above resource as podinfo-abtest.yaml and then apply it:
1
kubectl apply -f ./podinfo-abtest.yaml
Copied!
After a couple of seconds Flagger will create the canary objects:
1
# applied 
2
deployment.apps/podinfo
3
horizontalpodautoscaler.autoscaling/podinfo
4
canary.flagger.app/podinfo
5
​
6
# generated 
7
deployment.apps/podinfo-primary
8
horizontalpodautoscaler.autoscaling/podinfo-primary
9
service/podinfo
10
service/podinfo-canary
11
service/podinfo-primary
12
destinationrule.networking.istio.io/podinfo-canary
13
destinationrule.networking.istio.io/podinfo-primary
14
virtualservice.networking.istio.io/podinfo
Copied!
Automated canary promotion
Trigger a canary deployment by updating the container image:
1
kubectl -n test set image deployment/podinfo \
2
podinfod=stefanprodan/podinfo:3.1.1
Copied!
Flagger detects that the deployment revision changed and starts a new rollout:
1
kubectl -n test describe canary/abtest
2
​
3
Status:
4
  Failed Checks:         0
5
  Phase:                 Succeeded
6
Events:
7
  Type     Reason  Age   From     Message
8
  ----     ------  ----  ----     -------
9
  Normal   Synced  3m    flagger  New revision detected podinfo.test
10
  Normal   Synced  3m    flagger  Scaling up podinfo.test
11
  Warning  Synced  3m    flagger  Waiting for podinfo.test rollout to finish: 0 of 1 updated replicas are available
12
  Normal   Synced  3m    flagger  Advance podinfo.test canary iteration 1/10
13
  Normal   Synced  3m    flagger  Advance podinfo.test canary iteration 2/10
14
  Normal   Synced  3m    flagger  Advance podinfo.test canary iteration 3/10
15
  Normal   Synced  2m    flagger  Advance podinfo.test canary iteration 4/10
16
  Normal   Synced  2m    flagger  Advance podinfo.test canary iteration 5/10
17
  Normal   Synced  1m    flagger  Advance podinfo.test canary iteration 6/10
18
  Normal   Synced  1m    flagger  Advance podinfo.test canary iteration 7/10
19
  Normal   Synced  55s   flagger  Advance podinfo.test canary iteration 8/10
20
  Normal   Synced  45s   flagger  Advance podinfo.test canary iteration 9/10
21
  Normal   Synced  35s   flagger  Advance podinfo.test canary iteration 10/10
22
  Normal   Synced  25s   flagger  Copying podinfo.test template spec to podinfo-primary.test
23
  Warning  Synced  15s   flagger  Waiting for podinfo-primary.test rollout to finish: 1 of 2 updated replicas are available
24
  Normal   Synced  5s    flagger  Promotion completed! Scaling down podinfo.test
Copied!
Note that if you apply new changes to the deployment during the canary analysis, Flagger will restart the analysis.
You can monitor all canaries with:
1
watch kubectl get canaries --all-namespaces
2
​
3
NAMESPACE   NAME      STATUS        WEIGHT   LASTTRANSITIONTIME
4
test        podinfo   Progressing   100      2019-03-16T14:05:07Z
5
prod        frontend  Succeeded     0        2019-03-15T16:15:07Z
6
prod        backend   Failed        0        2019-03-14T17:05:07Z
Copied!
Automated rollback
During the canary analysis you can generate HTTP 500 errors and high latency to test Flagger's rollback.
Generate HTTP 500 errors:
1
watch curl -b 'type=insider' http://app.example.com/status/500
Copied!
Generate latency:
1
watch curl -b 'type=insider' http://app.example.com/delay/1
Copied!
When the number of failed checks reaches the canary analysis threshold, the traffic is routed back to the primary, the canary is scaled to zero and the rollout is marked as failed.
1
kubectl -n test describe canary/podinfo
2
​
3
Status:
4
  Failed Checks:         2
5
  Phase:                 Failed
6
Events:
7
  Type     Reason  Age   From     Message
8
  ----     ------  ----  ----     -------
9
  Normal   Synced  3m    flagger  Starting canary deployment for podinfo.test
10
  Normal   Synced  3m    flagger  Advance podinfo.test canary iteration 1/10
11
  Normal   Synced  3m    flagger  Advance podinfo.test canary iteration 2/10
12
  Normal   Synced  3m    flagger  Advance podinfo.test canary iteration 3/10
13
  Normal   Synced  3m    flagger  Halt podinfo.test advancement success rate 69.17% < 99%
14
  Normal   Synced  2m    flagger  Halt podinfo.test advancement success rate 61.39% < 99%
15
  Warning  Synced  2m    flagger  Rolling back podinfo.test failed checks threshold reached 2
16
  Warning  Synced  1m    flagger  Canary failed! Scaling down podinfo.test
Copied!
The above procedure can be extended with custom metrics checks, webhooks, manual promotion approval and Slack or MS Teams notifications.
Tutorials - Previous
Istio Canary Deployments
Next - Tutorials
Linkerd Canary Deployments
Last modified 8mo ago
Copy link
Contents
Prerequisites
Bootstrap
Automated canary promotion
Automated rollback