End of Sale Notice:

Commercial support for NGINX Service Mesh is available to customers who currently have active NGINX Microservices Bundle subscriptions. F5 NGINX announced the End of Sale (EoS) for the NGINX Microservices Bundles as of July 1, 2023.

See our End of Sale announcement for more details.

Expose a UDP Application with NGINX Ingress Controller

This topic describes the steps to deploy NGINX Ingress Controller for Kubernetes, to expose a UDP application within NGINX Service Mesh.

Overview

Follow this tutorial to deploy the NGINX Ingress Controller with NGINX Service Mesh and an example UDP application.

Objectives:

Deploy NGINX Service Mesh.
Install NGINX Ingress Controller.
Deploy the example udp-listener app.
Create a Kubernetes GlobalConfiguration resource to establish a NGINX Ingress Controller UDP listener.
Create a Kubernetes TransportServer resource for the udp-listener application.

Note:

NGINX Ingress Controller can be used for free with NGINX Open Source. Paying customers have access to NGINX Ingress Controller with NGINX Plus. To complete this tutorial, you must use either:

Open Source NGINX Ingress Controller version 3.0+

NGINX Plus version of NGINX Ingress Controller

Install NGINX Service Mesh

Follow the installation instructions to install NGINX Service Mesh on your Kubernetes cluster. UDP traffic proxying is disabled by default, so you will need to enable it using the --enable-udp flag when deploying. Linux kernel 4.18 or greater is required.

Caution:
Before proceeding, verify that the mesh is running (Step 2 of the installation instructions). NGINX Ingress Controller will try to fetch certs from the Spire agent that gets deployed by NGINX Service Mesh on startup. If the mesh is not running, NGINX Ingress controller will fail to start.

Install NGINX Ingress Controller

Install NGINX Ingress Controller with the option to allow UDP ingress traffic. This tutorial will demonstrate installation as a Deployment.
- Follow the instructions to enable UDP
Important:
```
mTLS does not affect UDP communication, as mTLS in NGINX Service Mesh applies only to TCP traffic at this time.
```
Get access to the NGINX Ingress Controller by applying the udp-nodeport.yaml NodePort resource.
- udp-nodeport.yaml

Check the exposed port from the NodePort service just defined:

$ kubectl get svc -n nginx-ingress
NAME                    TYPE       CLUSTER-IP      EXTERNAL-IP   PORT(S)                      AGE
nginx-ingress           NodePort   10.120.10.134   <none>        80:32705/TCP,443:30181/TCP   57m
udp-listener-nodeport   NodePort   10.120.4.106    <none>        8900:31839/UDP               6m35s

As you can see, our exposed port is 31839. We’ll use this for the remaining steps.

Get the IP of one of your worker nodes:

$ kubectl get node -o wide
NAME                                     ... INTERNAL-IP     EXTERNAL-IP ...
gke-aidan-dev-default-pool-f507f772-qiun ... 10.128.15.210   12.115.30.1  ...
gke-aidan-dev-default-pool-f507f772-tjpo ... 10.128.15.211   12.200.3.8  ...

We’ll use 12.115.30.1.

At this point, you should have the NGINX Ingress Controller running in your cluster; you can deploy the udp-listener example app to test out the mesh integration, or use NGINX Ingress controller to expose one of your own apps.

Deploy the udp-listener App

Enable automatic sidecar injection for the default namespace.
Download the manifest for the udp-listener app.
- udp-listener.yaml
Use kubectl to deploy the example udp-listener app.
```
kubectl apply -f udp-listener.yaml
```

Verify that all of the Pods are ready and in “Running” status:

kubectl get pod
NAME                            READY   STATUS    RESTARTS   AGE
udp-listener-59665d7ffc-drzh2   2/2     Running   0          4s

Expose the udp-listener App

To route UDP requests to an application in the mesh through the NGINX Ingress Controller, you will need both a GlobalConfiguration and TransportServer Resource.

Deploy a GlobalConfiguration to configure what port to listen for UDP requests on:

kubectl apply -f nic-global-configuration.yaml

The GlobalConfiguration configures a listener to listen for UDP datagrams on a specified port.

apiVersion: k8s.nginx.org/v1alpha1
kind: GlobalConfiguration
metadata:
name: nginx-configuration
namespace: nginx-ingress
spec:
listeners:
- name: accept-udp
  port: 8900
  protocol: UDP

Apply the TransportServer to configure UDP traffic to route from the GlobalConfiguration listener your udp-listener app.
```
kubectl apply -f udp-transportserver.yaml
```
This TransportServer will route requests from the listener supplied in the GlobalConfiguration to a named upstream – in this case udp-listener-upstream. Our upstream is configured to pass traffic to our udp-listener service at port 5005, where our udp-listener application lives.
```
apiVersion: k8s.nginx.org/v1alpha1
kind: TransportServer
metadata:
name: udp-listener
spec:
listener:
  name: accept-udp
  protocol: UDP
upstreams:
- name: udp-listener-upstream
  service: udp-listener
  port: 5005
upstreamParameters:
  udpRequests: 1
action:
  pass: udp-listener-upstream
```

Send Datagrams to the udp-listener App

Now that everything for the NGINX Ingress Controller is deployed, we can now send datagrams to the udp-listener application.

Use the IP and port defined in the Install NGINX Ingress Controller section to send a netcat UDP message:
```
echo "UDP Datagram Message" | nc -u 12.115.30.1 31839
```

Check that that the “UDP Datagram Message” text was correctly sent to the udp-listener server:

$ kubectl logs udp-listener-59665d7ffc-drzh2 -c udp-listener
Listening on UDP port 5005
UDP Datagram Message

Check that the UDP message is present in the udp-listener sidecar logs:

kubectl logs udp-listener-59665d7ffc-drzh2 -c nginx-mesh-sidecar
...
2022/01/22 00:09:31 SVID updated for spiffeID: "spiffe://example.org/ns/default/sa/default"
2022/01/22 00:09:31 Enqueueing event: SPIRE, key: 0xc00007ac00
2022/01/22 00:09:31 Dequeueing event: SPIRE, key: 0xc00007ac00
2022/01/22 00:09:31 Reloading nginx with configVersion: 2
2022/01/22 00:09:31 executing nginx -s reload
2022/01/22 00:09:32 success, version 2 ensured. iterations: 4. took: 100ms
[08/Feb/2022:19:49:02 +0000] 10.116.0.26:41802 UDP 200 0 49 0.000 "127.0.0.1:5005" "21" "0" "0.000"

We’re looking for the [08/Feb/2022:19:49:02 +0000] 10.116.0.26:41802 UDP 200 0 49 0.000 "127.0.0.1:5005" "21" "0" "0.000" line, which includes the UDP protocol and the correct size of the UDP packet we sent.

Notice the 49 bytes representing the incoming packet size. This correlates to the 28 bytes of headroom added to the packet to maintain original destination information. See the UDP and eBPF architecture section for more information on why this is necessary.