# Knative Canary Deployments This guide shows you how to use [Knative](https://knative.dev/) and Flagger to automate canary deployments. ![Flagger Canary Stages](https://raw.githubusercontent.com/fluxcd/flagger/main/docs/diagrams/flagger-gatewayapi-canary.png) ## Prerequisites Flagger requires a Kubernetes cluster **v1.19** or newer and a Knative Serving installation that supports the resources with `serving.knative.dev/v1` as their API version. Install Knative v1.17.0: ```bash kubectl apply -f https://github.com/knative/serving/releases/download/knative-v1.17.0/serving-crds.yaml kubectl apply -f https://github.com/knative/serving/releases/download/knative-v1.17.0/serving-core.yaml kubectl apply -f https://github.com/knative/net-kourier/releases/download/knative-v1.17.0/kourier.yaml kubectl patch configmap/config-network \ --namespace knative-serving \ --type merge \ --patch '{"data":{"ingress-class":"kourier.ingress.networking.knative.dev"}}' ``` Install Flagger in the `flagger-system` namespace: ```bash kubectl apply -k github.com/fluxcd/flagger//kustomize/knative ``` Create a namespace for your Kntive Service: ```bash kubectl create namespace test ``` Create a Knative Service that deploys podinfo: ```yaml apiVersion: serving.knative.dev/v1 kind: Service metadata: name: podinfo namespace: test spec: template: spec: containers: - image: ghcr.io/stefanprodan/podinfo:6.0.0 ports: - containerPort: 9898 protocol: TCP command: - ./podinfo - --port=9898 - --port-metrics=9797 - --grpc-port=9999 - --grpc-service-name=podinfo - --level=info - --random-delay=false - --random-error=false ``` Deploy the load testing service to generate traffic during the canary analysis: ```bash kubectl apply -k https://github.com/fluxcd/flagger//kustomize/tester?ref=main ``` Create a Canary custom resource: ```yaml apiVersion: flagger.app/v1beta1 kind: Canary metadata: name: podinfo namespace: test spec: provider: knative # knative service ref targetRef: apiVersion: serving.knative.dev/v1 kind: Service name: podinfo # the maximum time in seconds for the canary deployment # to make progress before it is rollback (default 600s) progressDeadlineSeconds: 60 analysis: # schedule interval (default 60s) interval: 15s # max number of failed metric checks before rollback threshold: 15 # max traffic percentage routed to canary maxWeight: 50 # canary increment step # percentage (0-100) stepWeight: 10 metrics: - name: request-success-rate # min success rate (non-5xx responses) # percentage (0-100) thresholdRange: min: 99 interval: 1m - name: request-duration # milliseconds thresholdRange: max: 500 interval: 1m webhooks: - name: load-test url: http://flagger-loadtester.test/ timeout: 5s metadata: type: cmd cmd: "hey -z 1m -q 5 -c 2 http://podinfo.test" logCmdOutput: "true" ``` > Note: Please note that for a Canary resource with `.spec.provider` set to `knative`, the resource is only valid if the `.spec.targetRef.kind` is `Service` and `.spec.targetRef.apiVersion` is `serving.knative.dev/v1`. Save the above resource as podinfo-canary.yaml and then apply it: ```bash kubectl apply -f ./podinfo-canary.yaml ``` When the canary analysis starts, Flagger will call the pre-rollout webhooks before routing traffic to the canary. The canary analysis will run for five minutes while validating the HTTP metrics and rollout hooks every minute. After a couple of seconds Flagger will make the following changes the Knative Service `podinfo`: * Add an annotation to the object with the name `flagger.app/primary-revision`. * Modify the `.spec.traffic` section of the object such that it can manipulate the traffic spread between the primary and canary Knative Revision. ## Automated canary promotion Trigger a canary deployment by updating the container image: ```bash kubectl -n test patch services.serving podinfo --type=json \ -p '[{"op": "replace", "path": "/spec/template/spec/containers/0/image", "value": "ghcr.io/stefanprodan/podinfo:6.0.1"}]' ``` Flagger detects that the deployment revision changed and starts a new rollout: ```text kubectl -n test describe canary/podinfo Status: Canary Weight: 0 Failed Checks: 0 Phase: Succeeded Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Synced 3m flagger New revision detected podinfo.test Normal Synced 3m flagger Scaling up podinfo.test Normal Synced 3m flagger Advance podinfo.test canary weight 5 Normal Synced 3m flagger Advance podinfo.test canary weight 10 Normal Synced 3m flagger Advance podinfo.test canary weight 15 Normal Synced 2m flagger Advance podinfo.test canary weight 20 Normal Synced 2m flagger Advance podinfo.test canary weight 25 Normal Synced 1m flagger Advance podinfo.test canary weight 30 Normal Synced 1m flagger Advance podinfo.test canary weight 35 Normal Synced 55s flagger Advance podinfo.test canary weight 40 Normal Synced 45s flagger Advance podinfo.test canary weight 45 Normal Synced 35s flagger Advance podinfo.test canary weight 50 Normal Synced 25s flagger Copying podinfo.test template spec to podinfo-primary.test Normal Synced 5s flagger Promotion completed! Scaling down podinfo.test ``` A canary deployment is triggered everytime a new Knative Revision is created. **Note** that if you apply new changes to the Knative Service during the canary analysis, Flagger will restart the analysis. You can monitor how Flagger progressively changes the Knative Service object to spread traffic between Knative Revisions: ```bash watch kubectl get httproute -n test podinfo -o=jsonpath='{.spec.traffic}' ``` You can monitor all canaries with: ```bash watch kubectl get canaries --all-namespaces NAMESPACE NAME STATUS WEIGHT LASTTRANSITIONTIME test podinfo Progressing 15 2025-03-16T14:05:07Z prod frontend Succeeded 0 2025-03-16T16:15:07Z prod backend Failed 0 2025-03-16T17:05:07Z ``` ## Automated rollback During the canary analysis you can generate HTTP 500 errors and high latency to test if Flagger pauses the rollout. Trigger another canary deployment: ```bash kubectl -n test patch services.serving podinfo --type=json \ -p '[{"op": "replace", "path": "/spec/template/spec/containers/0/image", "value": "ghcr.io/stefanprodan/podinfo:6.0.2"}]' ``` Exec into the load tester pod with: ```bash kubectl -n test exec -it flagger-loadtester-xx-xx sh ``` Generate HTTP 500 errors: ```bash watch curl http://podinfo-canary:9898/status/500 ``` Generate latency: ```bash watch curl http://podinfo-canary:9898/delay/1 ``` When the number of failed checks reaches the canary analysis threshold, the traffic is routed back to the primary Knative Revision and the rollout is marked as failed. ```text kubectl -n test describe canary/podinfo Status: Canary Weight: 0 Failed Checks: 10 Phase: Failed Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Synced 3m flagger Starting canary deployment for podinfo.test Normal Synced 3m flagger Advance podinfo.test canary weight 5 Normal Synced 3m flagger Advance podinfo.test canary weight 10 Normal Synced 3m flagger Advance podinfo.test canary weight 15 Normal Synced 3m flagger Halt podinfo.test advancement error rate 69.17% > 1% Normal Synced 2m flagger Halt podinfo.test advancement error rate 61.39% > 1% Normal Synced 2m flagger Halt podinfo.test advancement error rate 55.06% > 1% Normal Synced 2m flagger Halt podinfo.test advancement error rate 47.00% > 1% Normal Synced 2m flagger (combined from similar events): Halt podinfo.test advancement error rate 38.08% > 1% Warning Synced 1m flagger Rolling back podinfo.test failed checks threshold reached 10 Warning Synced 1m flagger Canary failed! Scaling down podinfo.test ```