TIS1106 - Subset Not Found

A referenced subset was not found, leading to configuration errors in routing.

Recommendation: Ensure Subsets Are Defined and Properly Referenced

To prevent routing errors, ensure that subsets referenced in VirtualService configurations are correctly defined in DestinationRule resources. Fix typos or define missing subsets as needed.

Examples

1. VirtualService Referring to a Non-Existent Subset

   apiVersion: networking.istio.io/v1beta1
   kind: VirtualService
   metadata:
     name: my-virtual-service
     namespace: example-namespace
   spec:
     hosts:
     - "my-app.example.com"
     http:
     - route:
       - destination:
           host: "my-app-service.example-namespace.svc.cluster.local"
           subset: "v1"

   Explanation: The VirtualService references a subset named v1, but no corresponding subset is defined in the DestinationRule. This causes routing issues, as Istio cannot find the specified subset.

Recommendation

Fix the routes pointing to non-existent subsets by either correcting typos in the subset name or defining the missing subset in the DestinationRule.

1. Correct Typo in Subset Name

   If the subset name is incorrect, update the VirtualService to reference the correct subset name.

   apiVersion: networking.istio.io/v1beta1
   kind: VirtualService
   metadata:
     name: my-virtual-service
     namespace: example-namespace
   spec:
     hosts:
     - "my-app.example.com"
     http:
     - route:
       - destination:
           host: "my-app-service.example-namespace.svc.cluster.local"
           subset: "v1-corrected"

   Explanation: Correcting the subset name ensures that Istio can properly match the route to an existing subset, allowing the routing to function as intended.

2. Define the Missing Subset in DestinationRule

   If the subset is missing, define it in a DestinationRule to ensure it is recognized by Istio.

   apiVersion: networking.istio.io/v1beta1
   kind: DestinationRule
   metadata:
     name: my-app-destination-rule
     namespace: example-namespace
   spec:
     host: "my-app-service.example-namespace.svc.cluster.local"
     subsets:
     - name: "v1"
       labels:
         version: "v1"

   Explanation: Defining the subset in the DestinationRule ensures that the subset exists and matches the VirtualService configuration, enabling proper routing to the desired version of the service.