Session affinity incompatible with destinations weight

- consistent hashing does not apply across multiple subsets

artifacts/routing/destination-rule.yaml

@@ -0,0 +1,45 @@
+apiVersion: networking.istio.io/v1alpha3
+kind: VirtualService
+metadata:
+  name: podinfo
+  namespace: test
+spec:
+  gateways:
+    - public-gateway.istio-system.svc.cluster.local
+    - mesh
+  hosts:
+    - podinfo.istio.weavedx.com
+    - podinfo
+  http:
+    - route:
+        - destination:
+            host: podinfo
+            subset: primary
+          weight: 50
+        - destination:
+            host: podinfo
+            subset: canary
+          weight: 50
+---
+apiVersion: networking.istio.io/v1alpha3
+kind: DestinationRule
+metadata:
+  name: podinfo-destination
+  namespace: test
+spec:
+  host: podinfo
+  trafficPolicy:
+    loadBalancer:
+      consistentHash:
+        httpCookie:
+          name: istiouser
+          ttl: 30s
+  subsets:
+    - name: primary
+      labels:
+        app: podinfo
+        role: primary
+    - name: canary
+      labels:
+        app: podinfo
+        role: canary