# NGINX Canary Deployments This guide shows you how to use the NGINX ingress controller and Flagger to automate canary deployments and A/B testing. ![Flagger NGINX Ingress Controller](https://raw.githubusercontent.com/fluxcd/flagger/main/docs/diagrams/flagger-nginx-overview.png) ## Prerequisites Flagger requires a Kubernetes cluster **v1.19** or newer and NGINX ingress **v1.0.2** or newer. Install the NGINX ingress controller with Helm v3: ```bash helm repo add ingress-nginx https://kubernetes.github.io/ingress-nginx kubectl create ns ingress-nginx helm upgrade -i ingress-nginx ingress-nginx/ingress-nginx \ --namespace ingress-nginx \ --set controller.metrics.enabled=true \ --set controller.podAnnotations."prometheus\.io/scrape"=true \ --set controller.podAnnotations."prometheus\.io/port"=10254 ``` Install Flagger and the Prometheus add-on in the same namespace as the ingress controller: ```bash helm repo add flagger https://flagger.app helm upgrade -i flagger flagger/flagger \ --namespace ingress-nginx \ --set prometheus.install=true \ --set meshProvider=nginx ``` ## Bootstrap Flagger takes a Kubernetes deployment and optionally a horizontal pod autoscaler (HPA), then creates a series of objects (Kubernetes deployments, ClusterIP services and canary ingress). These objects expose the application outside the cluster and drive the canary analysis and promotion. Create a test namespace: ```bash kubectl create ns test ``` Create a deployment and a horizontal pod autoscaler: ```bash kubectl apply -k https://github.com/fluxcd/flagger//kustomize/podinfo?ref=main ``` Deploy the load testing service to generate traffic during the canary analysis: ```bash helm upgrade -i flagger-loadtester flagger/loadtester \ --namespace=test ``` Create an ingress definition (replace `app.example.com` with your own domain): ```yaml apiVersion: networking.k8s.io/v1 kind: Ingress metadata: name: podinfo namespace: test labels: app: podinfo annotations: kubernetes.io/ingress.class: "nginx" spec: rules: - host: "app.example.com" http: paths: - pathType: Prefix path: "/" backend: service: name: podinfo port: number: 80 ``` Save the above resource as podinfo-ingress.yaml and then apply it: ```bash kubectl apply -f ./podinfo-ingress.yaml ``` Create a canary custom resource (replace `app.example.com` with your own domain): ```yaml apiVersion: flagger.app/v1beta1 kind: Canary metadata: name: podinfo namespace: test spec: provider: nginx # deployment reference targetRef: apiVersion: apps/v1 kind: Deployment name: podinfo # ingress reference ingressRef: apiVersion: networking.k8s.io/v1 kind: Ingress name: podinfo # HPA reference (optional) autoscalerRef: apiVersion: autoscaling/v2 kind: HorizontalPodAutoscaler name: podinfo # the maximum time in seconds for the canary deployment # to make progress before it is rollback (default 600s) progressDeadlineSeconds: 60 service: # ClusterIP port number port: 80 # container port number or name targetPort: 9898 analysis: # schedule interval (default 60s) interval: 10s # max number of failed metric checks before rollback threshold: 10 # max traffic percentage routed to canary # percentage (0-100) maxWeight: 50 # canary increment step # percentage (0-100) stepWeight: 5 # NGINX Prometheus checks metrics: - name: request-success-rate # minimum req success rate (non 5xx responses) # percentage (0-100) thresholdRange: min: 99 interval: 1m # testing (optional) webhooks: - name: acceptance-test type: pre-rollout url: http://flagger-loadtester.test/ timeout: 30s metadata: type: bash cmd: "curl -sd 'test' http://podinfo-canary/token | grep token" - name: load-test url: http://flagger-loadtester.test/ timeout: 5s metadata: cmd: "hey -z 1m -q 10 -c 2 http://app.example.com/" ``` Save the above resource as podinfo-canary.yaml and then apply it: ```bash kubectl apply -f ./podinfo-canary.yaml ``` After a couple of seconds Flagger will create the canary objects: ```bash # applied deployment.apps/podinfo horizontalpodautoscaler.autoscaling/podinfo ingresses.extensions/podinfo canary.flagger.app/podinfo # generated deployment.apps/podinfo-primary horizontalpodautoscaler.autoscaling/podinfo-primary service/podinfo service/podinfo-canary service/podinfo-primary ingresses.extensions/podinfo-canary ``` ## Automated canary promotion Flagger implements a control loop that gradually shifts traffic to the canary while measuring key performance indicators like HTTP requests success rate, requests average duration and pod health. Based on analysis of the KPIs a canary is promoted or aborted, and the analysis result is published to Slack or MS Teams. ![Flagger Canary Stages](https://raw.githubusercontent.com/fluxcd/flagger/main/docs/diagrams/flagger-canary-steps.png) Trigger a canary deployment by updating the container image: ```bash kubectl -n test set image deployment/podinfo \ podinfod=ghcr.io/stefanprodan/podinfo:6.0.1 ``` Flagger detects that the deployment revision changed and starts a new rollout: ``` 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 Warning Synced 3m flagger Waiting for podinfo.test rollout to finish: 0 of 1 updated replicas are available 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 Warning Synced 15s flagger Waiting for podinfo-primary.test rollout to finish: 1 of 2 updated replicas are available Normal Synced 5s flagger Promotion completed! Scaling down podinfo.test ``` **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: ```bash watch kubectl get canaries --all-namespaces NAMESPACE NAME STATUS WEIGHT LASTTRANSITIONTIME test podinfo Progressing 15 2019-05-06T14:05:07Z prod frontend Succeeded 0 2019-05-05T16:15:07Z prod backend Failed 0 2019-05-04T17:05:07Z ``` ## Automated rollback During the canary analysis you can generate HTTP 500 errors to test if Flagger pauses and rolls back the faulted version. Trigger another canary deployment: ```bash kubectl -n test set image deployment/podinfo \ podinfod=ghcr.io/stefanprodan/podinfo:6.0.2 ``` Generate HTTP 500 errors: ```bash watch curl http://app.example.com/status/500 ``` 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. ``` 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 success rate 69.17% < 99% Normal Synced 2m flagger Halt podinfo.test advancement success rate 61.39% < 99% Normal Synced 2m flagger Halt podinfo.test advancement success rate 55.06% < 99% Normal Synced 2m flagger Halt podinfo.test advancement success rate 47.00% < 99% Normal Synced 2m flagger (combined from similar events): Halt podinfo.test advancement success rate 38.08% < 99% Warning Synced 1m flagger Rolling back podinfo.test failed checks threshold reached 10 Warning Synced 1m flagger Canary failed! Scaling down podinfo.test ``` ## Custom metrics The canary analysis can be extended with Prometheus queries. The demo app is instrumented with Prometheus so you can create a custom check that will use the HTTP request duration histogram to validate the canary. Create a metric template and apply it on the cluster: ```yaml apiVersion: flagger.app/v1beta1 kind: MetricTemplate metadata: name: latency namespace: test spec: provider: type: prometheus address: http://flagger-prometheus.ingress-nginx:9090 query: | histogram_quantile(0.99, sum( rate( http_request_duration_seconds_bucket{ kubernetes_namespace="{{ namespace }}", kubernetes_pod_name=~"{{ target }}-[0-9a-zA-Z]+(-[0-9a-zA-Z]+)" }[1m] ) ) by (le) ) ``` Edit the canary analysis and add the latency check: ```yaml analysis: metrics: - name: "latency" templateRef: name: latency thresholdRange: max: 0.5 interval: 1m ``` The threshold is set to 500ms so if the average request duration in the last minute goes over half a second then the analysis will fail and the canary will not be promoted. Trigger a canary deployment by updating the container image: ```bash kubectl -n test set image deployment/podinfo \ podinfod=ghcr.io/stefanprodan/podinfo:6.0.3 ``` Generate high response latency: ```bash watch curl http://app.example.com/delay/2 ``` Watch Flagger logs: ``` kubectl -n nginx-ingress logs deployment/flagger -f | jq .msg Starting canary deployment for podinfo.test Advance podinfo.test canary weight 5 Advance podinfo.test canary weight 10 Advance podinfo.test canary weight 15 Halt podinfo.test advancement latency 1.20 > 0.5 Halt podinfo.test advancement latency 1.45 > 0.5 Halt podinfo.test advancement latency 1.60 > 0.5 Halt podinfo.test advancement latency 1.69 > 0.5 Halt podinfo.test advancement latency 1.70 > 0.5 Rolling back podinfo.test failed checks threshold reached 5 Canary failed! Scaling down podinfo.test ``` If you have alerting configured, Flagger will send a notification with the reason why the canary failed. ## A/B Testing 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](https://raw.githubusercontent.com/fluxcd/flagger/main/docs/diagrams/flagger-abtest-steps.png) Edit the canary analysis, remove the max/step weight and add the match conditions and iterations: ```yaml analysis: interval: 1m threshold: 10 iterations: 10 match: # curl -H 'X-Canary: insider' http://app.example.com - headers: x-canary: exact: "insider" # curl -b 'canary=always' http://app.example.com - headers: cookie: exact: "canary" metrics: - name: request-success-rate thresholdRange: min: 99 interval: 1m webhooks: - name: load-test url: http://flagger-loadtester.test/ timeout: 5s metadata: cmd: "hey -z 1m -q 10 -c 2 -H 'Cookie: canary=always' http://app.example.com/" ``` The above configuration will run an analysis for ten minutes targeting users that have a `canary` cookie set to `always` or those that call the service using the `X-Canary: insider` header. Trigger a canary deployment by updating the container image: ```bash kubectl -n test set image deployment/podinfo \ podinfod=ghcr.io/stefanprodan/podinfo:6.0.4 ``` Flagger detects that the deployment revision changed and starts the A/B testing: ``` kubectl -n test describe canary/podinfo Status: 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 Warning Synced 3m flagger Waiting for podinfo.test rollout to finish: 0 of 1 updated replicas are available Normal Synced 3m flagger Advance podinfo.test canary iteration 1/10 Normal Synced 3m flagger Advance podinfo.test canary iteration 2/10 Normal Synced 3m flagger Advance podinfo.test canary iteration 3/10 Normal Synced 2m flagger Advance podinfo.test canary iteration 4/10 Normal Synced 2m flagger Advance podinfo.test canary iteration 5/10 Normal Synced 1m flagger Advance podinfo.test canary iteration 6/10 Normal Synced 1m flagger Advance podinfo.test canary iteration 7/10 Normal Synced 55s flagger Advance podinfo.test canary iteration 8/10 Normal Synced 45s flagger Advance podinfo.test canary iteration 9/10 Normal Synced 35s flagger Advance podinfo.test canary iteration 10/10 Normal Synced 25s flagger Copying podinfo.test template spec to podinfo-primary.test Warning Synced 15s flagger Waiting for podinfo-primary.test rollout to finish: 1 of 2 updated replicas are available Normal Synced 5s flagger Promotion completed! Scaling down podinfo.test ``` The above procedure can be extended with [custom metrics](https://docs.flagger.app/main/usage/metrics) checks, [webhooks](https://docs.flagger.app/main/usage/webhooks), [manual promotion](https://docs.flagger.app/main/usage/webhooks#manual-gating) approval and [Slack or MS Teams](https://docs.flagger.app/main/usage/alerting) notifications.