TIS1101 - DestinationWeight on Route Does Not Have a Valid Service

The DestinationWeight on a route does not point to a valid service (host not found).

Recommendation: Ensure DestinationWeight References a Valid Service

To avoid routing failures, always ensure that the host in the destination section of the VirtualService references a valid service in the service registry. Correct the host, deploy the missing service, or remove the invalid configuration as appropriate.

Examples

1. VirtualService with Invalid Host in DestinationWeight

   apiVersion: networking.istio.io/v1beta1
   kind: VirtualService
   metadata:
     name: my-virtual-service
     namespace: example-namespace
   spec:
     hosts:
     - "my-app.example-namespace.svc.cluster.local"
     http:
     - route:
       - destination:
           host: "unknown-service.example-namespace.svc.cluster.local"
           weight: 100

   Explanation: The VirtualService references a host unknown-service.example-namespace.svc.cluster.local in the destination section, but no corresponding service exists in the service registry. This causes routing failures, as Istio cannot determine where to send the traffic.

Recommendation

Correct the host to point to a valid service in the namespace, use an FQDN if referring to a service in another namespace, deploy the missing service, or remove the configuration linking to the non-existent service.

1. Correct the Host to an Existing Service

   Update the host in the destination to point to a valid service.

   apiVersion: networking.istio.io/v1beta1
   kind: VirtualService
   metadata:
     name: my-virtual-service
     namespace: example-namespace
   spec:
     hosts:
     - "my-app.example-namespace.svc.cluster.local"
     http:
     - route:
       - destination:
           host: "existing-service.example-namespace.svc.cluster.local"
           weight: 100

   Explanation: Correcting the host to an existing service (existing-service.example-namespace.svc.cluster.local) ensures that the traffic can be correctly routed by Istio.

2. Deploy the Missing Service

   If the service should exist but is missing, deploy it to the mesh.

   apiVersion: v1
   kind: Service
   metadata:
     name: unknown-service
     namespace: example-namespace
   spec:
     ports:
     - protocol: TCP
       port: 80
       targetPort: 8080
     selector:
       app: unknown-service

   Explanation: Deploying the missing service allows Istio to find the specified host and route traffic appropriately.

3. Remove the Invalid Configuration

   If the configuration is not needed, remove the destination referencing the non-existent service.

   apiVersion: networking.istio.io/v1beta1
   kind: VirtualService
   metadata:
     name: my-virtual-service
     namespace: example-namespace
   spec:
     hosts:
     - "my-app.example-namespace.svc.cluster.local"
     http:
     - route: []

   Explanation: Removing the invalid configuration helps to avoid routing issues caused by referencing a non-existent service.