TIS0301 - Multiple Gateways for Same Host-Port Combination

Multiple Gateway resources exist for the same host-port combination.

Recommendation: Avoid Duplicate Gateway Configurations

To prevent conflicts and ensure consistent behavior, remove duplicate Gateway entries or merge the definitions into a single resource for the same host-port combination.

Examples

1. Two Gateway Objects Targeting the Same Host and Port

   First Gateway:

   apiVersion: networking.istio.io/v1beta1
   kind: Gateway
   metadata:
     name: gateway-1
     namespace: example-namespace
   spec:
     selector:
       istio: ingressgateway
     servers:
     - port:
         number: 80
         name: http
         protocol: HTTP
       hosts:
       - "example.com"

   Second Gateway:

   apiVersion: networking.istio.io/v1beta1
   kind: Gateway
   metadata:
     name: gateway-2
     namespace: example-namespace
   spec:
     selector:
       istio: ingressgateway
     servers:
     - port:
         number: 80
         name: http
         protocol: HTTP
       hosts:
       - "example.com"

   Explanation: Both Gateway resources define a server that listens on port 80 for the host example.com. Having multiple Gateway resources with the same host-port combination can lead to conflicts and undefined behavior, as Istio may not know which configuration to apply.

Recommendation

Remove duplicate gateway entries or merge the definitions into a single Gateway.

1. Remove Duplicate Gateway Entry

   If one of the Gateway resources is redundant, remove it to avoid conflicts.

   kubectl delete gateway gateway-2 -n example-namespace

2. Merge Gateway Definitions

   Alternatively, merge the definitions into a single Gateway to include all necessary configuration for the host-port combination.

   apiVersion: networking.istio.io/v1beta1
   kind: Gateway
   metadata:
     name: merged-gateway
     namespace: example-namespace
   spec:
     selector:
       istio: ingressgateway
     servers:
     - port:
         number: 80
         name: http
         protocol: HTTP
       hosts:
       - "example.com"