UDP routing

Gateway API is designed to work with multiple protocols and UDPRoute is one such route which allows for managing UDP traffic.

In this example, we have one Gateway resource and two UDPRoute resources that distribute the traffic with the following rules:

• All UDP datagrams on port 8080 of the Gateway are forwarded to port 6000 of my-foo-service Kubernetes Service.
• All UDP datagrams on port 8090 of the Gateway are forwarded to port 6000 of my-bar-service Kubernetes Service.

In this example two UDP listeners will be applied to the Gateway in order to route traffic to two separate backend UDPRoutes, note that the protocol set for the listeners on the Gateway is UDP:

apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: my-udp-gateway
spec:
  gatewayClassName: my-udp-gateway-class
  listeners:
    - name: foo
      protocol: UDP
      port: 8080
      allowedRoutes:
        kinds:
          - kind: UDPRoute
    - name: bar
      protocol: UDP
      port: 8090
      allowedRoutes:
        kinds:
          - kind: UDPRoute
---
apiVersion: gateway.networking.k8s.io/v1
kind: UDPRoute
metadata:
  name: udp-app-1
spec:
  parentRefs:
    - name: my-udp-gateway
      sectionName: foo
  rules:
    - backendRefs:
        - name: my-foo-service
          port: 6000
---
apiVersion: gateway.networking.k8s.io/v1
kind: UDPRoute
metadata:
  name: udp-app-2
spec:
  parentRefs:
    - name: my-udp-gateway
      sectionName: bar
  rules:
    - backendRefs:
        - name: my-bar-service
          port: 6000

In the above example we separate the traffic for the two separate backend UDP Services by using the sectionName field in the parentRefs to refer to a specific named listener:

spec:
  parentRefs:
    - name: my-udp-gateway
      sectionName: foo

This corresponds directly with the name in the listeners in the Gateway:

listeners:
  - name: foo
    protocol: UDP
    port: 8080
  - name: bar
    protocol: UDP
    port: 8090

In this way each UDPRoute “attaches” itself to a different port on the Gateway so that the service my-foo-service receives traffic for port 8080 and my-bar-service receives traffic for port 8090.

Note that you can achieve this same result by binding the Routes to the Gateway listeners using the port field in the parentRefs:

spec:
  parentRefs:
    - name: my-udp-gateway
      port: 8080

Using the port field instead of sectionName for the attachment has the downside of more tightly coupling the relationship between the Gateway and its associated Routes. Refer to Attaching to Gateways for more details.