add docs for istio sticky canary releases

Signed-off-by: Sanskar Jaiswal <jaiswalsanskar078@gmail.com>
2026-04-15 06:57:34 +00:00 · 2022-11-15 17:55:52 +05:30
parent 14ccda5506
commit d16c9696c3
2 changed files with 170 additions and 0 deletions
@@ -292,6 +292,118 @@ Events:
  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](../usage/deployment-strategies.md#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/v2beta2
+    kind: HorizontalPodAutoscaler
+    name: podinfo
+  service:
+    # service port number
+    port: 9898
+    # container port number or name (optional)
+    targetPort: 9898
+    # Istio gateways (optional)
+    gateways:
+    - public-gateway.istio-system.svc.cluster.local
+    # 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)