Use Cloudflare Tunnels with Kubernetes client-go plugin

Use Cloudflare Tunnels with Kubernetes client-go credential plugins

This tutorial explains how to use Cloudflare Tunnels with Kubernetes client-go credential plugins for authentication. By following these steps, you can securely access your Kubernetes cluster through a Cloudflare Tunnel using the kubectl command-line tool.

Prerequisites

• A Cloudflare account
• The Cloudflare Tunnel client (cloudflared) installed on your machine
• Access to a Kubernetes cluster
• kubectl installed on your machine

1. Set up a Cloudflare Tunnel

1. Authenticate cloudflared with your Cloudflare account:

   cloudflared tunnel login

2. Create a new tunnel:

   cloudflared tunnel create k8s-tunnel

3. Configure your tunnel by creating a configuration file named config.yml:

   tunnel: <TUNNEL_ID>
   credentials-file: /path/to/credentials.json
   ingress:
     - hostname: k8s.example.com
       service: tcp://kubernetes.default.svc.cluster.local:443
     - service: http_status:404

   Replace <TUNNEL_ID> with your tunnel ID and adjust the hostname as needed.

4. Start the tunnel:

   cloudflared tunnel run k8s-tunnel

2. Configure the Kubernetes API server

Ensure your Kubernetes API server is configured to accept authentication from Cloudflare Tunnels. This may involve setting up an authentication webhook or configuring the API server to trust the Cloudflare Tunnel's client certificates.

3. Set up client-go credential plugin

1. Create a script named cloudflare-k8s-auth.sh with the following content:

   #!/bin/bash
   
   echo '{
     "apiVersion": "client.authentication.k8s.io/v1beta1",
     "kind": "ExecCredential",
     "status": {
       "token": "'"$(cloudflared access token -app=https://k8s.example.com)"'"
     }
   }'

   Make the script executable:

   chmod +x cloudflare-k8s-auth.sh

2. Update your ~/.kube/config file to use the credential plugin:

   apiVersion: v1
   kind: Config
   clusters:
   - cluster:
       server: https://k8s.example.com
     name: cloudflare-k8s
   users:
   - name: cloudflare-user
     user:
       exec:
         apiVersion: client.authentication.k8s.io/v1beta1
         command: /path/to/cloudflare-k8s-auth.sh
         interactiveMode: Never
   contexts:
   - context:
       cluster: cloudflare-k8s
       user: cloudflare-user
     name: cloudflare-k8s-context
   current-context: cloudflare-k8s-context

4. Use kubectl with Cloudflare Tunnel

Now you can use kubectl commands as usual. The client-go credential plugin will automatically handle authentication through the Cloudflare Tunnel:

kubectl get pods

Troubleshooting

If you encounter issues:

• Ensure cloudflared is running and the tunnel is active
• Check that your ~/.kube/config file is correctly configured
• Verify that the Kubernetes API server is properly set up to accept authentication from Cloudflare Tunnels
• Review the Cloudflare Tunnel logs for any error messages

For more information, refer to the Cloudflare Tunnels documentation ↗ and the Kubernetes client-go credential plugins documentation ↗.