# Istio Canary Deployments This guide shows you how to use Istio and Flagger to automate canary deployments. ![Flagger Canary Stages](https://raw.githubusercontent.com/fluxcd/flagger/main/docs/diagrams/flagger-canary-steps.png) ## Prerequisites Flagger requires a Kubernetes cluster **v1.16** or newer and Istio **v1.5** or newer. Install Istio with telemetry support and Prometheus: ```bash istioctl manifest install --set profile=default # Suggestion: Please change release-1.8 in below command, to your real istio version. kubectl apply -f https://raw.githubusercontent.com/istio/istio/release-1.18/samples/addons/prometheus.yaml ``` Install Flagger in the `istio-system` namespace: ```bash kubectl apply -k github.com/fluxcd/flagger//kustomize/istio ``` Create an ingress gateway to expose the demo app outside of the mesh: ```yaml apiVersion: networking.istio.io/v1alpha3 kind: Gateway metadata: name: public-gateway namespace: istio-system spec: selector: istio: ingressgateway servers: - port: number: 80 name: http protocol: HTTP hosts: - "*" ``` ## Bootstrap Flagger takes a Kubernetes deployment and optionally a horizontal pod autoscaler (HPA), then creates a series of objects (Kubernetes deployments, ClusterIP services, Istio destination rules and virtual services). These objects expose the application inside the mesh and drive the canary analysis and promotion. Create a test namespace with Istio sidecar injection enabled: ```bash kubectl create ns test kubectl label namespace test istio-injection=enabled ``` 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 kubectl apply -k https://github.com/fluxcd/flagger//kustomize/tester?ref=main ``` Create a canary custom resource (replace example.com with your own domain): ```yaml apiVersion: flagger.app/v1beta1 kind: Canary metadata: name: podinfo namespace: test spec: # deployment reference targetRef: apiVersion: apps/v1 kind: Deployment name: podinfo # the maximum time in seconds for the canary deployment # to make progress before it is rollback (default 600s) progressDeadlineSeconds: 60 # HPA reference (optional) autoscalerRef: apiVersion: autoscaling/v2 kind: HorizontalPodAutoscaler name: podinfo service: # service port number port: 9898 # container port number or name (optional) targetPort: 9898 # Istio gateways (optional) gateways: - istio-system/public-gateway # Istio virtual service host names (optional) hosts: - app.example.com # Istio traffic policy (optional) trafficPolicy: tls: # use ISTIO_MUTUAL when mTLS is enabled mode: DISABLE # Istio retry policy (optional) retries: attempts: 3 perTryTimeout: 1s retryOn: "gateway-error,connect-failure,refused-stream" analysis: # schedule interval (default 60s) interval: 1m # max number of failed metric checks before rollback threshold: 5 # max traffic percentage routed to canary # percentage (0-100) maxWeight: 50 # canary increment step # percentage (0-100) stepWeight: 10 metrics: - name: request-success-rate # minimum req success rate (non 5xx responses) # percentage (0-100) thresholdRange: min: 99 interval: 1m - name: request-duration # maximum req duration P99 # milliseconds thresholdRange: max: 500 interval: 30s # 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:9898/token | grep token" - name: load-test url: http://flagger-loadtester.test/ timeout: 5s metadata: cmd: "hey -z 1m -q 10 -c 2 http://podinfo-canary.test:9898/" ``` **Note** that when using Istio 1.4 you have to replace the `request-duration` with a [metric template](https://docs.flagger.app/dev/upgrade-guide#istio-telemetry-v2). 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. ![Flagger Canary Process](https://raw.githubusercontent.com/fluxcd/flagger/main/docs/diagrams/flagger-canary-hpa.png) After a couple of seconds Flagger will create the canary objects: ```bash # applied deployment.apps/podinfo horizontalpodautoscaler.autoscaling/podinfo canary.flagger.app/podinfo # generated deployment.apps/podinfo-primary horizontalpodautoscaler.autoscaling/podinfo-primary service/podinfo service/podinfo-canary service/podinfo-primary destinationrule.networking.istio.io/podinfo-canary destinationrule.networking.istio.io/podinfo-primary virtualservice.networking.istio.io/podinfo ``` ## Automated canary promotion 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. A canary deployment is triggered by changes in any of the following objects: * Deployment PodSpec (container image, command, ports, env, resources, etc) * ConfigMaps mounted as volumes or mapped to environment variables * Secrets mounted as volumes or mapped to environment variables You can monitor all canaries with: ```bash watch kubectl get canaries --all-namespaces NAMESPACE NAME STATUS WEIGHT LASTTRANSITIONTIME test podinfo Progressing 15 2019-01-16T14:05:07Z prod frontend Succeeded 0 2019-01-15T16:15:07Z prod backend Failed 0 2019-01-14T17:05:07Z ``` ## 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 set image deployment/podinfo \ podinfod=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, 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 ``` ## Session Affinity While Flagger can perform weighted routing and A/B testing individually, with Istio it can combine the two leading to a Canary release with session affinity. For more information you can read the [deployment strategies docs](https://docs.flagger.app/main/usage/deployment-strategies#canary-release-with-session-affinity). 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: # deployment reference targetRef: apiVersion: apps/v1 kind: Deployment name: podinfo # the maximum time in seconds for the canary deployment # to make progress before it is rollback (default 600s) progressDeadlineSeconds: 60 # HPA reference (optional) autoscalerRef: apiVersion: autoscaling/v2 kind: HorizontalPodAutoscaler name: podinfo service: # service port number port: 9898 # container port number or name (optional) targetPort: 9898 # Istio gateways (optional) gateways: - istio-system/public-gateway # Istio virtual service host names (optional) hosts: - app.example.com # Istio traffic policy (optional) trafficPolicy: tls: # use ISTIO_MUTUAL when mTLS is enabled mode: DISABLE # Istio retry policy (optional) retries: attempts: 3 perTryTimeout: 1s retryOn: "gateway-error,connect-failure,refused-stream" analysis: # schedule interval (default 60s) interval: 1m # max number of failed metric checks before rollback threshold: 5 # max traffic percentage routed to canary # percentage (0-100) maxWeight: 50 # canary increment step # percentage (0-100) stepWeight: 10 # session affinity config sessionAffinity: # name of the cookie used cookieName: flagger-cookie # max age of the cookie (in seconds) # optional; defaults to 86400 maxAge: 21600 metrics: - name: request-success-rate # minimum req success rate (non 5xx responses) # percentage (0-100) thresholdRange: min: 99 interval: 1m - name: request-duration # maximum req duration P99 # milliseconds thresholdRange: max: 500 interval: 30s # 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:9898/token | grep token" - name: load-test url: http://flagger-loadtester.test/ timeout: 5s metadata: cmd: "hey -z 1m -q 10 -c 2 http://podinfo-canary.test:9898/" ``` Save the above resource as podinfo-canary-session-affinity.yaml and then apply it: ```bash kubectl apply -f ./podinfo-canary-session-affinity.yaml ``` 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 ``` You can load `app.example.com` in your browser and refresh it until you see the requests being served by `podinfo:6.0.1`. All subsequent requests after that will be served by `podinfo:6.0.1` and not `podinfo:6.0.0` because of the session affinity configured by Flagger with Istio. ## Traffic mirroring ![Flagger Canary Traffic Shadowing](https://raw.githubusercontent.com/fluxcd/flagger/main/docs/diagrams/flagger-canary-traffic-mirroring.png) For applications that perform read operations, Flagger can be configured to drive canary releases with traffic mirroring. Istio traffic mirroring will copy each incoming request, sending one request to the primary and one to the canary service. The response from the primary is sent back to the user and the response from the canary is discarded. Metrics are collected on both requests so that the deployment will only proceed if the canary metrics are within the threshold values. Note that mirroring should be used for requests that are **idempotent** or capable of being processed twice (once by the primary and once by the canary). You can enable mirroring by replacing `stepWeight/maxWeight` with `iterations` and by setting `analysis.mirror` to `true`: ```yaml apiVersion: flagger.app/v1beta1 kind: Canary metadata: name: podinfo namespace: test spec: analysis: # schedule interval interval: 1m # max number of failed metric checks before rollback threshold: 5 # total number of iterations iterations: 10 # enable traffic shadowing mirror: true # weight of the traffic mirrored to your canary (defaults to 100%) mirrorWeight: 100 metrics: - name: request-success-rate thresholdRange: min: 99 interval: 1m - name: request-duration thresholdRange: max: 500 interval: 1m webhooks: - name: acceptance-test type: pre-rollout url: http://flagger-loadtester.test/ timeout: 30s metadata: type: bash cmd: "curl -sd 'test' http://podinfo-canary:9898/token | grep token" - name: load-test url: http://flagger-loadtester.test/ timeout: 5s metadata: cmd: "hey -z 1m -q 10 -c 2 http://podinfo.test:9898/" ``` With the above configuration, Flagger will run a canary release with the following steps: * detect new revision (deployment spec, secrets or configmaps changes) * scale from zero the canary deployment * wait for the HPA to set the canary minimum replicas * check canary pods health * run the acceptance tests * abort the canary release if tests fail * start the load tests * mirror 100% of the traffic from primary to canary * check request success rate and request duration every minute * abort the canary release if the metrics check failure threshold is reached * stop traffic mirroring after the number of iterations is reached * route live traffic to the canary pods * promote the canary (update the primary secrets, configmaps and deployment spec) * wait for the primary deployment rollout to finish * wait for the HPA to set the primary minimum replicas * check primary pods health * switch live traffic back to primary * scale to zero the canary * send notification with the canary analysis result 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. ## Canary Deployments for TCP Services Performing a Canary deployment on a TCP (non HTTP) service is nearly identical to an HTTP Canary. Besides updating your `Gateway` document to support the `TCP` routing, the only difference is you have to set the `appProtocol` field to `TCP` inside of the `service` section of your `Canary` document. #### Example: ```yaml apiVersion: networking.istio.io/v1alpha3 kind: Gateway metadata: name: public-gateway namespace: istio-system spec: selector: istio: ingressgateway servers: - port: number: 7070 name: tcp-service protocol: TCP # <== set the protocol to tcp here hosts: - "*" ``` ```yaml apiVersion: flagger.app/v1beta1 kind: Canary # omitted for brevity spec: service: port: 7070 appProtocol: TCP # <== set the appProtocol here targetPort: 7070 portName: "tcp-service-port" ``` If the `appProtocol` equals `TCP` then Flagger will treat this as a Canary deployment for a `TCP` service. When it creates the `VirtualService` document it will add a `TCP` section to route requests between the `primary` and `canary` services. See Istio documentation for more information on this [spec](https://istio.io/latest/docs/reference/config/networking/virtual-service/#TCPRoute). The resulting `VirtualService` will include a `tcp` section similar to what is shown below: ```yaml tcp: - route: - destination: host: tcp-service-primary port: number: 7070 weight: 100 - destination: host: tcp-service-canary port: number: 7070 weight: 0 ``` Once the Canary analysis begins, Flagger will be able to adjust the weights inside of this `tcp` section to advance the Canary deployment until it either runs into an error (and is halted) or it successfully reaches the end of the analysis and is Promoted. It is also important to note that if you set `appProtocol` to anything other than `TCP`, for example if you set it to `HTTP`, it will perform the Canary and treat it as an `HTTP` service. The same remains true if you do not set `appProtocol` at all. It will **ONLY** treat a Canary as a `TCP` service if `appProtocal` equals `TCP`.