TIS0103 - Specified Host Not Found in Service Registry

The specified host does not have a corresponding entry in the service registry.

Recommendation: Ensure Hosts Have Corresponding Entries in the Service Registry

To prevent routing issues, ensure that all hosts specified in your Istio configuration have corresponding entries in the service registry. Correct any typographical errors, remove non-existent hosts, or create new service, service entry, or virtual service configurations for the desired host.

Examples

1. VirtualService Refers to Non-Existent Host

   apiVersion: networking.istio.io/v1beta1
   kind: VirtualService
   metadata:
     name: invalid-host-virtual-service
     namespace: example-namespace
   spec:
     hosts:
     - "non-existent-service.example-namespace.svc.cluster.local"
     http:
     - route:
       - destination:
           host: "non-existent-service.example-namespace.svc.cluster.local"

   Explanation: The VirtualService references a host non-existent-service.example-namespace.svc.cluster.local that does not have an entry in the service registry, resulting in a routing failure.

2. DestinationRule with Invalid Host

   apiVersion: networking.istio.io/v1beta1
   kind: DestinationRule
   metadata:
     name: invalid-host-destination-rule
     namespace: example-namespace
   spec:
     host: "unknown-service.example-namespace.svc.cluster.local"
     trafficPolicy:
       loadBalancer:
         simple: ROUND_ROBIN

   Explanation: The DestinationRule specifies a host unknown-service.example-namespace.svc.cluster.local that does not exist in the service registry, making the rule ineffective.

3. ServiceEntry with Invalid Host

   apiVersion: networking.istio.io/v1beta1
   kind: ServiceEntry
   metadata:
     name: service-entry-invalid-host
     namespace: example-namespace
   spec:
     hosts:
     - "unknown-external-service.com"
     location: MESH_EXTERNAL
     ports:
     - number: 80
       name: http
       protocol: HTTP

   Explanation: The ServiceEntry defines an external host unknown-external-service.com, but it does not have a corresponding entry in the service registry, making the service unavailable for communication.

Recommendation

Remove the host from the list, correct any typographical errors, or deploy a new service, service entry, or virtual service pointing to the host.

1. Correct the Hostname to an Existing Service

   Ensure that the host specified is correct and matches an existing service in the service registry.

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

2. Deploy the Missing Service

   If the host is intended to exist, deploy the service before applying the configuration.

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: non-existent-service
     namespace: example-namespace
   spec:
     replicas: 1
     selector:
       matchLabels:
         app: non-existent-service
     template:
       metadata:
         labels:
           app: non-existent-service
       spec:
         containers:
         - name: my-container
           image: my-image

3. Create a ServiceEntry for the Host

   If the host is external, create a ServiceEntry to add it to the service registry.

   apiVersion: networking.istio.io/v1beta1
   kind: ServiceEntry
   metadata:
     name: service-entry-valid-host
     namespace: example-namespace
   spec:
     hosts:
     - "external-service.com"
     location: MESH_EXTERNAL
     ports:
     - number: 80
       name: http
       protocol: HTTP