Easily open TCP and UDP protocols on the same port

If you’ve ever tried to expose both TCP and UDP on the same port using Kubernetes with AWS Load Balancers, you’ve probably run into a common limitation: you can only choose one protocol per port, which complicates applications that need both (such as real-time communications or gaming).

The good news is that AWS has released a feature that allows configuring listeners for both TCP and UDP on the same port, avoiding complex workarounds.

To implement this, it’s important to verify two things:

• That your AWS Load Balancer Controller is version v2.13.0 or higher.
• That the Helm chart is 1.13.0 or higher to ensure compatibility.

Once that’s set, you only need to do two steps to enable both protocols on the same port:

1. In the ALB Controller’s values.yaml file, add:

   controllerConfig:
       featureGates:
           EnableTCPUDPListener: true
   

2. In the LoadBalancer type Service manifest where you want to enable this functionality, add this annotation:

   service.beta.kubernetes.io/aws-load-balancer-enable-tcp-udp-listener: 'true'
   

After that, you just need to define the port twice in your Service: once for TCP and once for UDP. Here is a complete example of a Service manifest that opens the same port for both TCP and UDP:

apiVersion: v1
kind: Service
metadata:
  name: ejemplo-tcp-udp
  annotations:
    service.beta.kubernetes.io/aws-load-balancer-enable-tcp-udp-listener: "true"
spec:
  type: LoadBalancer
  selector:
    app: mi-aplicacion
  ports:
    - name: tcp-12345
      protocol: TCP
      port: 12345
      targetPort: 12345
    - name: udp-12345
      protocol: UDP
      port: 12345
      targetPort: 12345

⚠️ If you already had the load balancer created and you add this functionality now, I recommend deleting it and recreating it to ensure the configuration is applied correctly.

💬 References

This new feature addresses several community-reported issues, such as #2759 and 1608. I hope this is helpful to those following those threads!