blumeops/mise-tasks/ensure-k3s-ringtail-kubectl-config

#!/usr/bin/env bash
#MISE description="Ensure kubectl config for k3s-ringtail is set up on this workstation"

set -euo pipefail

CONFIG_DIR="$HOME/.kube/k3s-ringtail"
CONFIG_FILE="$CONFIG_DIR/config.yml"

echo "Ensuring k3s-ringtail kubectl config..."

# Create directory if needed
mkdir -p "$CONFIG_DIR"

# Fetch kubeconfig from ringtail and extract the CA cert
echo "Fetching kubeconfig from ringtail..."
RAW_CONFIG=$(ssh ringtail 'sudo cat /etc/rancher/k3s/k3s.yaml')

# Extract and decode the CA certificate
echo "$RAW_CONFIG" | grep certificate-authority-data | awk '{print $2}' | base64 -d > "$CONFIG_DIR/ca.crt"

# Extract and decode the client certificate
echo "$RAW_CONFIG" | grep client-certificate-data | awk '{print $2}' | base64 -d > "$CONFIG_DIR/client.crt"

# Extract and decode the client key
echo "$RAW_CONFIG" | grep client-key-data | awk '{print $2}' | base64 -d > "$CONFIG_DIR/client.key"
chmod 600 "$CONFIG_DIR/client.key"

# Write kubeconfig with file-based certs and tailscale hostname
cat > "$CONFIG_FILE" << EOF
apiVersion: v1
kind: Config
clusters:
- cluster:
    certificate-authority: $CONFIG_DIR/ca.crt
    server: https://ringtail.tail8d86e.ts.net:6443
  name: k3s-ringtail
contexts:
- context:
    cluster: k3s-ringtail
    user: k3s-ringtail
  name: k3s-ringtail
current-context: k3s-ringtail
users:
- name: k3s-ringtail
  user:
    client-certificate: $CONFIG_DIR/client.crt
    client-key: $CONFIG_DIR/client.key
EOF

echo "Config written to $CONFIG_FILE"

# Warn if KUBECONFIG doesn't include this file
if [[ -z "${KUBECONFIG:-}" ]] || [[ ":$KUBECONFIG:" != *":$CONFIG_FILE:"* ]]; then
    echo ""
    echo "WARNING: KUBECONFIG does not include $CONFIG_FILE"
    echo "Add this to your shell config:"
    echo "  export KUBECONFIG=\"\$KUBECONFIG:$CONFIG_FILE\""
fi

echo ""
echo "Test with: kubectl --context=k3s-ringtail get nodes"