Expose TCP and UDP services#

Note

You must have MKE admin access to configure TCP and UDP services.
Prior to setting up TCP and UDP services, verify that you have correctly configured kubectl.

Kubernetes Ingress only supports services over HTTP and HTTPS. Using NGINX Ingress Controller, though, you can circumvent this limitation to enable situations in which it may be necessary to expose TCP and UDP services.

The following example procedure exposes a TCP service on port 9000 and a UDP service on port 5005:

Deploy a sample TCP service listening on port 9000, to echo back any text it receives with the prefix hello.

cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Service
metadata:
  name: tcp-echo
  labels:
    app: tcp-echo
    service: tcp-echo
spec:
  selector:
    app: tcp-echo
  ports:
  - name: tcp
    port: 9000

---

apiVersion: apps/v1
kind: Deployment
metadata:
  name: tcp-echo
spec:
  replicas: 1
  selector:
    matchLabels:
      app: tcp-echo
  template:
    metadata:
      labels:
        app: tcp-echo
    spec:
      containers:
      - name: tcp-echo
        image: docker.io/istio/tcp-echo-server:1.2
        imagePullPolicy: IfNotPresent
        args: [ "9000", "hello" ]
        ports:
        - containerPort: 9000
EOF

Deploy a sample UDP service listening on port 5005.

cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: ServiceAccount
metadata:
  name: udp-listener

---

apiVersion: apps/v1
kind: Deployment
metadata:
  name: udp-listener
  labels:
    app: udp-listener
spec:
  replicas: 1
  selector:
    matchLabels:
      app: udp-listener
  template:
    metadata:
      labels:
        app: udp-listener
    spec:
      containers:
      - name: udp-listener
        image: mendhak/udp-listener
        ports:
        - containerPort: 5005
          protocol: UDP
          name: udp

---

apiVersion: v1
kind: Service
metadata:
  name: udp-listener
spec:
  ports:
  - port: 5005
    targetPort: 5005
    protocol: UDP
    name: udp
  selector:
    app: udp-listener
EOF

Verify that the two services are running correctly.

Run kubectl get deploy tcp-echo udp-listener to verify that the deployment was created.

Example output:

NAME           READY   UP-TO-DATE   AVAILABLE   AGE
tcp-echo       1/1     1            1           39s
udp-listener   1/1     1            1           31s

Run kubectl get service tcp-echo udp-listener to list the services created.

Example output:

NAME           TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)    AGE
tcp-echo       ClusterIP   10.96.172.90   <none>        9000/TCP   46s
udp-listener   ClusterIP   10.96.19.229   <none>        5005/UDP   37s

Configure Ingress Controller to expose the TCP and UDP services.

Verify that the enabled parameter for the cluster_config.ingress_controller option in the MKE configuration file is set to true.

Modify the MKE configuration file to expose the newly created TCP and UDP services, as shown below:

[cluster_config.ingress_controller]
    enabled = true

...

[[cluster_config.ingress_controller.ingress_exposed_ports]]
    name = "proxied-tcp-9000"
    port = 9000
    target_port = 9000
    node_port = 33011
    protocol = "TCP"

[[cluster_config.ingress_controller.ingress_exposed_ports]]
    name = "proxied-udp-5005"
    port = 5005
    target_port = 5005
    node_port = 33012
    protocol = "UDP"

...

[cluster_config.ingress_controller.ingress_tcp_services]
  9000 = "default/tcp-echo:9000"
[cluster_config.ingress_controller.ingress_udp_services]
  5005 = "default/udp-listener:5005"

...

Upload the modified MKE configuration file to complete the operation. For more information, refer to Use an MKE configuration file.

Note

To configure NGINX Ingress Controller using the MKE web UI, in the left-side navigation panel, navigate to > Admin Settings > Ingress.

Test the TCP service.

Send the text world. The service should respond with hello world:

export MKE_HOST=<mke host>

echo "world" | netcat $MKE_HOST 33011
hello world

Check the tcp-echo logs:

kubectl get pods --selector=app=tcp-echo

Example output:

NAME                        READY   STATUS    RESTARTS   AGE
tcp-echo-5cf4d68d76-p2c9b   1/1     Running   0          6m6s

kubectl logs tcp-echo-5cf4d68d76-p2c9b

Example output:

listening on [::]:9000, prefix: hello
request: world
response: hello world

Test the UDP service.

Send the text UDP Datagram Message:

echo "UDP Datagram Message" | netcat -v -u $MKE_HOST 33012

Check the udp-listneer logs to verify that receipt:

kubectl get pods --selector=app=udp-listener

Example output:

NAME                            READY   STATUS    RESTARTS   AGE
udp-listener-59cdc755d7-qr2bl   1/1     Running   0          93m

kubectl logs udp-listener-59cdc755d7-qr2bl

Example output:

Listening on UDP port 5005
UDP Datagram Message

UDP Datagram Message

Remove the Kubernetes resources, as they are no longer needed.

kubectl delete service tcp-echo
kubectl delete deployment tcp-echo
kubectl delete service udp-listener
kubectl delete deployment udp-listener

Important

If the services are not reachable:

Verify that ports 33011 and 33012 are open on both the node and on the firewall of the cloud platform.

Review the logs of the sample applications for error messages:

kubectl logs -l app=tcp-echo and kubectl logs -l app=ucp-listener

Review the NGINX Ingress Controller logs for error messages:

kubectl logs -l app.kubernetes.io/name=ingress-nginx -n ingress-nginx