How to route requests from a gateway resource in k8s that takes in UDP traffic?

Question

Generally, what I do is, if it is tcp traffic, I create a virtualservice listening to the tcp gateway and route it to the correct host. like so -

apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  creationTimestamp: "2024-03-19T17:17:44Z"
  generation: 2
  name: tcp-test-virtual-service
  namespace: default
  resourceVersion: "1076485"
  uid: 9cc94534-2dec-4165-8dec-4a8fb66087ea
spec:
  gateways:
  - tcp-test
  hosts:
  - '*'
  tcp:
  - match:
    - port: 2057
    route:
    - destination:
        host: tcp-test
        port:
          number: 2057

But The virtualservice resource in k8s does not allow

spec:
  udp:

It returns this error -

denied the request: configuration is invalid: http, tcp or tls must be provided in virtual service

How can I direct incoming traffic on my UDP gateway?

Answer 1

Based on this link that is posted in stackoverflow UDP is not supported in istio. However from the same link it was mentioned from one of the answers that there will be an update wherein UDP protocol will be supported.

However, upon checking the documentation of istio VirtualService it seems that there is still no configuration for UDP ports.

But upon searching for this concern I bump into this documentation titled “Exposing TCP and UDP based services in Istio - The Easy Way” Based from the documentation wherein the scenario is there is already a service created and they edit it and add TCP. But it was indicated that it can also do UDP ports.

From the example

KUBE_EDITOR="nano" kubectl edit svc -n istio-system istio-ingressgateway

# Add this within the ports section of the svc.
...
- name: redis
  port: 6379
  protocol: TCP #can be also UDP for udp service
  targetPort: 6379
 …

As you can see from the comment with # it was mentioned that it could also change to UDP for UDP service. For this concern make sure that your service is exposing UDP ports.