mirror of https://github.com/fluxcd/flagger.git
218 lines
7.1 KiB
Markdown
218 lines
7.1 KiB
Markdown
# Istio A/B Testing
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This guide shows you how to automate A/B testing with Istio and Flagger.
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Besides weighted routing, Flagger can be configured to route traffic to the canary based on HTTP match conditions.
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In an A/B testing scenario, you'll be using HTTP headers or cookies to target a certain segment of your users.
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This is particularly useful for frontend applications that require session affinity.
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### Bootstrap
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Create a test namespace with Istio sidecar injection enabled:
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```bash
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kubectl create ns test
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kubectl label namespace test istio-injection=enabled
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```
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Create a deployment and a horizontal pod autoscaler:
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```bash
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kubectl apply -k github.com/weaveworks/flagger//kustomize/podinfo
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```
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Deploy the load testing service to generate traffic during the canary analysis:
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```bash
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kubectl apply -k github.com/weaveworks/flagger//kustomize/tester
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```
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Create a canary custom resource (replace example.com with your own domain):
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```yaml
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apiVersion: flagger.app/v1alpha3
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kind: Canary
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metadata:
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name: podinfo
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namespace: test
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spec:
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# deployment reference
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targetRef:
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apiVersion: apps/v1
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kind: Deployment
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name: podinfo
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# the maximum time in seconds for the canary deployment
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# to make progress before it is rollback (default 600s)
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progressDeadlineSeconds: 60
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# HPA reference (optional)
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autoscalerRef:
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apiVersion: autoscaling/v2beta1
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kind: HorizontalPodAutoscaler
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name: podinfo
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service:
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# container port
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port: 9898
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# Istio gateways (optional)
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gateways:
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- public-gateway.istio-system.svc.cluster.local
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# Istio virtual service host names (optional)
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hosts:
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- app.example.com
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# Istio traffic policy (optional)
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trafficPolicy:
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tls:
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# use ISTIO_MUTUAL when mTLS is enabled
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mode: DISABLE
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canaryAnalysis:
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# schedule interval (default 60s)
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interval: 1m
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# total number of iterations
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iterations: 10
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# max number of failed iterations before rollback
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threshold: 2
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# canary match condition
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match:
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- headers:
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user-agent:
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regex: "^(?!.*Chrome).*Safari.*"
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- headers:
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cookie:
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regex: "^(.*?;)?(type=insider)(;.*)?$"
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metrics:
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- name: request-success-rate
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# minimum req success rate (non 5xx responses)
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# percentage (0-100)
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threshold: 99
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interval: 1m
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- name: request-duration
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# maximum req duration P99
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# milliseconds
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threshold: 500
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interval: 30s
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# generate traffic during analysis
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webhooks:
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- name: load-test
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url: http://flagger-loadtester.test/
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timeout: 5s
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metadata:
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cmd: "hey -z 1m -q 10 -c 2 -H 'Cookie: type=insider' http://podinfo.test:9898/"
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```
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The above configuration will run an analysis for ten minutes targeting Safari users and those that have an insider cookie.
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Save the above resource as podinfo-abtest.yaml and then apply it:
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```bash
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kubectl apply -f ./podinfo-abtest.yaml
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```
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After a couple of seconds Flagger will create the canary objects:
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```bash
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# applied
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deployment.apps/podinfo
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horizontalpodautoscaler.autoscaling/podinfo
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canary.flagger.app/podinfo
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# generated
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deployment.apps/podinfo-primary
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horizontalpodautoscaler.autoscaling/podinfo-primary
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service/podinfo
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service/podinfo-canary
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service/podinfo-primary
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destinationrule.networking.istio.io/podinfo-canary
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destinationrule.networking.istio.io/podinfo-primary
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virtualservice.networking.istio.io/podinfo
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```
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### Automated canary promotion
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Trigger a canary deployment by updating the container image:
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```bash
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kubectl -n test set image deployment/abtest \
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podinfod=stefanprodan/podinfo:3.1.1
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```
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Flagger detects that the deployment revision changed and starts a new rollout:
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```text
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kubectl -n test describe canary/abtest
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Status:
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Failed Checks: 0
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Phase: Succeeded
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Events:
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Type Reason Age From Message
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---- ------ ---- ---- -------
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Normal Synced 3m flagger New revision detected podinfo.test
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Normal Synced 3m flagger Scaling up podinfo.test
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Warning Synced 3m flagger Waiting for podinfo.test rollout to finish: 0 of 1 updated replicas are available
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Normal Synced 3m flagger Advance podinfo.test canary iteration 1/10
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Normal Synced 3m flagger Advance podinfo.test canary iteration 2/10
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Normal Synced 3m flagger Advance podinfo.test canary iteration 3/10
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Normal Synced 2m flagger Advance podinfo.test canary iteration 4/10
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Normal Synced 2m flagger Advance podinfo.test canary iteration 5/10
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Normal Synced 1m flagger Advance podinfo.test canary iteration 6/10
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Normal Synced 1m flagger Advance podinfo.test canary iteration 7/10
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Normal Synced 55s flagger Advance podinfo.test canary iteration 8/10
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Normal Synced 45s flagger Advance podinfo.test canary iteration 9/10
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Normal Synced 35s flagger Advance podinfo.test canary iteration 10/10
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Normal Synced 25s flagger Copying podinfo.test template spec to abtest-primary.test
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Warning Synced 15s flagger Waiting for abtest-primary.test rollout to finish: 1 of 2 updated replicas are available
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Normal Synced 5s flagger Promotion completed! Scaling down podinfo.test
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```
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**Note** that if you apply new changes to the deployment during the canary analysis, Flagger will restart the analysis.
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You can monitor all canaries with:
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```bash
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watch kubectl get canaries --all-namespaces
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NAMESPACE NAME STATUS WEIGHT LASTTRANSITIONTIME
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test abtest Progressing 100 2019-03-16T14:05:07Z
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prod frontend Succeeded 0 2019-03-15T16:15:07Z
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prod backend Failed 0 2019-03-14T17:05:07Z
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```
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### Automated rollback
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During the canary analysis you can generate HTTP 500 errors and high latency to test Flagger's rollback.
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Generate HTTP 500 errors:
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```bash
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watch curl -b 'type=insider' http://app.example.com/status/500
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```
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Generate latency:
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```bash
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watch curl -b 'type=insider' http://app.example.com/delay/1
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```
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When the number of failed checks reaches the canary analysis threshold, the traffic is routed back to the primary,
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the canary is scaled to zero and the rollout is marked as failed.
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```text
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kubectl -n test describe canary/abtest
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Status:
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Failed Checks: 2
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Phase: Failed
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Events:
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Type Reason Age From Message
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---- ------ ---- ---- -------
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Normal Synced 3m flagger Starting canary deployment for podinfo.test
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Normal Synced 3m flagger Advance podinfo.test canary iteration 1/10
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Normal Synced 3m flagger Advance podinfo.test canary iteration 2/10
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Normal Synced 3m flagger Advance podinfo.test canary iteration 3/10
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Normal Synced 3m flagger Halt podinfo.test advancement success rate 69.17% < 99%
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Normal Synced 2m flagger Halt podinfo.test advancement success rate 61.39% < 99%
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Warning Synced 2m flagger Rolling back podinfo.test failed checks threshold reached 2
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Warning Synced 1m flagger Canary failed! Scaling down podinfo.test
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```
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