Proxy TCP traffic by port

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TL;DR

Create a TCPRoute or TCPIngress resource, which will then be converted in to a Kong Gateway Service and Route.

Prerequisites

If you don’t have a Konnect account, you can get started quickly with our onboarding wizard.

  1. The following Konnect items are required to complete this tutorial:
    • Personal access token (PAT): Create a new personal access token by opening the Konnect PAT page and selecting Generate Token.
  2. Set the personal access token as an environment variable:

    export KONNECT_TOKEN='YOUR KONNECT TOKEN'
    
  1. Install the experimental Gateway API CRDs before installing Kong Ingress Controller:

    kubectl apply -f https://github.com/kubernetes-sigs/gateway-api/releases/download/v1.3.0/experimental-install.yaml
    
  2. Create a Gateway and GatewayClass instance to use.

echo "
apiVersion: v1
kind: Namespace
metadata:
  name: kong
---
apiVersion: gateway.networking.k8s.io/v1
kind: GatewayClass
metadata:
  name: kong
  annotations:
    konghq.com/gatewayclass-unmanaged: 'true'
spec:
  controllerName: konghq.com/kic-gateway-controller
---
apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: kong
spec:
  gatewayClassName: kong
  listeners:
  - name: proxy
    port: 80
    protocol: HTTP
    allowedRoutes:
      namespaces:
         from: All
" | kubectl apply -n kong -f -

Use the Konnect API to create a new CLUSTER_TYPE_K8S_INGRESS_CONTROLLER Control Plane:

CONTROL_PLANE_DETAILS=$(curl -X POST "https://us.api.konghq.com/v2/control-planes" \
     -H "Authorization: Bearer $KONNECT_TOKEN" \
     --json '{
       "name": "My KIC CP",
       "cluster_type": "CLUSTER_TYPE_K8S_INGRESS_CONTROLLER"
     }')

We’ll need the id and telemetry_endpoint for the values.yaml file later. Save them as environment variables:

CONTROL_PLANE_ID=$(echo $CONTROL_PLANE_DETAILS | jq -r .id)
CONTROL_PLANE_TELEMETRY=$(echo $CONTROL_PLANE_DETAILS | jq -r '.config.telemetry_endpoint | sub("https://";"")')

Create mTLS certificates

Kong Ingress Controller talks to Konnect over a connected secured with TLS certificates.

Generate a new certificate using openssl:

openssl req -new -x509 -nodes -newkey rsa:2048 -subj "/CN=kongdp/C=US" -keyout ./tls.key -out ./tls.crt

The certificate needs to be a single line string to send it to the Konnect API with curl. Use awk to format the certificate:

export CERT=$(awk 'NF {sub(/\r/, ""); printf "%s\\n",$0;}' tls.crt);

Next, upload the certificate to Konnect:

curl -X POST "https://us.api.konghq.com/v2/control-planes/$CONTROL_PLANE_ID/dp-client-certificates" \
     -H "Authorization: Bearer $KONNECT_TOKEN" \
     --json '{
       "cert": "'$CERT'"
     }'

Finally, store the certificate in a Kubernetes secret so that Kong Ingress Controller can read it:

kubectl create namespace kong -o yaml --dry-run=client | kubectl apply -f -
kubectl create secret tls konnect-client-tls -n kong --cert=./tls.crt --key=./tls.key
  1. Add the Kong Helm charts:

    helm repo add kong https://charts.konghq.com
    helm repo update
    
  2. Install Kong Ingress Controller using Helm:

    helm install kong kong/ingress -n kong --create-namespace --set controller.ingressController.env.feature_gates="GatewayAlpha=true"
    
  3. Set $PROXY_IP as an environment variable for future commands:

    export PROXY_IP=$(kubectl get svc --namespace kong kong-gateway-proxy -o jsonpath='{range .status.loadBalancer.ingress[0]}{@.ip}{@.hostname}{end}')
    echo $PROXY_IP
    

This how-to requires some Kubernetes services to be available in your cluster. These services will be used by the resources created in this how-to.

kubectl apply -f https://developer.konghq.com/manifests/kic/echo-service.yaml -n kong

Expose additional ports

Kong Gateway doesn’t include any TCP listen configuration by default. To expose TCP listens, update the Deployment’s environment variables and port configuration.

  1. Set the KONG_STREAM_LISTEN environment variable and expose port 9000 in the Deployment:

     kubectl patch deploy -n kong kong-gateway --patch '{
       "spec": {
         "template": {
           "spec": {
             "containers": [
               {
                 "name": "proxy",
                 "env": [
                   {
                     "name": "KONG_STREAM_LISTEN",
                     "value": "0.0.0.0:9000"
                   }
                 ],
                 "ports": [
                   {
                     "containerPort": 9000,
                     "name": "stream9000",
                     "protocol": "TCP"
                   }
                 ]
               }
             ]
           }
         }
       }
     }'
    
  2. Update the proxy Service to indicate the new ports:

    kubectl patch service -n kong kong-gateway-proxy --patch '{
      "spec": {
        "ports": [
          {
            "name": "stream9000",
            "port": 9000,
            "protocol": "TCP",
            "targetPort": 9000
          }
        ]
      }
    }'
    

Route TCP traffic

To publicly expose the Service, create a TCPRoute resource for Gateway APIs or a TCPIngress resource for Ingress.

This configuration instructs Kong Gateway to forward all traffic it receives on port 9000 to the echo Service on port 1025.

Validate your configuration

You can now test your Route using telnet:

telnet $PROXY_IP 9000

After you connect, type some text that you want as a response from the echo Service.

Trying 192.0.2.3...
Connected to 192.0.2.3.
Escape character is '^]'.
Welcome, you are connected to node gke-harry-k8s-dev-pool-1-e9ebab5e-c4gw.
Running on Pod echo-844545646c-gvmkd.
In namespace default.
With IP address 192.0.2.7.
This text will be echoed back.
This text will be echoed back.
^]
telnet> Connection closed.

To exit, press ctrl+] then ctrl+d.

Cleanup

kubectl delete -n kong -f https://developer.konghq.com/manifests/kic/echo-service.yaml
helm uninstall kong -n kong
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