kube-vip/cmd/kube-vip-kubeadm.go

package cmd

import (
	"fmt"
	"os"

	log "log/slog"

	"github.com/kube-vip/kube-vip/pkg/kubevip"
	"github.com/spf13/cobra"
)

// kubeadm adds two subcommands for managing a vip during a kubeadm init/join
// It is designed to operate "light" and take minimal input to start

func init() {
	kubeKubeadmJoin.Flags().StringVar(&kubeConfigPath, "config", "/etc/kubernetes/admin.conf", "The path of a Kubernetes configuration file")

	kubeKubeadm.AddCommand(kubeKubeadmInit)
	kubeKubeadm.AddCommand(kubeKubeadmJoin)
}

var kubeKubeadm = &cobra.Command{
	Use:   "kubeadm",
	Short: "Kubeadm functions",
	Long: `This command group provides utilities for generating static Pod manifests specifically tailored for the kubeadm bootstrapping process.
	It contains two subcommands:
  		- init:  Generates a manifest to be used during 'kubeadm init' on the first control-plane node.
  		- join:  Generates a manifest to be used during 'kubeadm join' for additional control-plane nodes.

The generated YAML manifest should be saved to the kubeadm static Pod directory (typically /etc/kubernetes/manifests/) so that kubeadm launches the kube-vip static Pod automatically.`,
	Run: func(cmd *cobra.Command, _ []string) {
		_ = cmd.Help()
	},
}

var kubeKubeadmInit = &cobra.Command{
	Use:   "init",
	Short: "kube-vip init",
	Long: `The 'init' subcommand generates a Kubernetes Pod manifest that kubeadm will start as a static Pod during the cluster initialisation phase.

This manifest runs kube-vip on the first control-plane node to advertise the Virtual IP (VIP) for the API server. The VIP is typically configured using ARP (Layer 2) or BGP (dynamic routing).

Required flags for this command:
  --interface   : The network interface to bind the VIP to (e.g., eth0).
  --vip or --address : The Virtual IP address or DNS name to use.

Example:
  kube-vip kubeadm init --interface eth0 --vip 192.168.1.100 --controlplane

The output YAML should be written to the kubeadm manifests directory, e.g.:
  kube-vip kubeadm init ... > /etc/kubernetes/manifests/kube-vip.yaml`,
	Run: func(cmd *cobra.Command, _ []string) {

		initConfig.LoadBalancers = append(initConfig.LoadBalancers, initLoadBalancer)
		err := kubevip.ParseEnvironment(&initConfig)
		if err != nil {
			log.Error("parsing environment", "err", err)
			return
		}
		if err := initConfig.Validate(); err != nil {
			log.Error("validating configuration", "err", err)
			return
		}

		// TODO - check for certain things VIP/interfaces
		if initConfig.Interface == "" {
			_ = cmd.Help()
			log.Error("No interface is specified for kube-vip to bind to")
			return
		}

		if initConfig.VIP == "" && initConfig.Address == "" {
			_ = cmd.Help()
			log.Error("No address is specified for kube-vip to expose services on")
			return
		}

		// Ensure there is an address to generate the CIDR from
		if initConfig.VIPSubnet == "" && initConfig.Address != "" {
			initConfig.VIPSubnet, err = GenerateCidrRange(initConfig.Address, initConfig.DNSMode)
			if err != nil {
				log.Error("generating VIPSubnet", "err", err)
				return
			}
		}

		cfg, err := kubevip.GeneratePodManifestFromConfig(&initConfig, image, Release.Version, inCluster)
		if err != nil {
			log.Error("unable to create manifest", "err", err)
			return
		}
		fmt.Println(cfg) // output manifest to stdout
	},
}

var kubeKubeadmJoin = &cobra.Command{
	Use:   "join",
	Short: "kube-vip join",
	Long: `The 'join' subcommand generates a Kubernetes Pod manifest for additional control-plane nodes joining an existing cluster via 'kubeadm join'.

It functions identically to the 'init' subcommand, but is intended for secondary control-plane nodes. It validates that the kubeconfig file (specified by --config, defaulting to /etc/kubernetes/admin.conf) exists on the node to ensure the node can authenticate with the cluster.

Required flags for this command:
  --interface   : The network interface to bind the VIP to.
  --vip or --address : The Virtual IP address or DNS name (must match the VIP used during 'init').

Example:
  kube-vip kubeadm join --interface eth0 --vip 192.168.1.100

The output YAML should be saved to the kubeadm manifests directory on the joining node.`,
	Run: func(cmd *cobra.Command, _ []string) {

		initConfig.LoadBalancers = append(initConfig.LoadBalancers, initLoadBalancer)
		err := kubevip.ParseEnvironment(&initConfig)
		if err != nil {
			log.Error("parsing environment", "err", err)
			return
		}
		if err := initConfig.Validate(); err != nil {
			log.Error("validating configuration", "err", err)
			return
		}

		// TODO - check for certain things VIP/interfaces
		if initConfig.Interface == "" {
			_ = cmd.Help()
			log.Error("No interface is specified for kube-vip to bind to")
			return
		}

		if initConfig.VIP == "" && initConfig.Address == "" {
			_ = cmd.Help()
			log.Error("No address is specified for kube-vip to expose services on")
			return
		}

		if _, err := os.Stat(kubeConfigPath); os.IsNotExist(err) {
			log.Error("kubeConfig not found", "Path", kubeConfigPath)
			return
		}

		// Ensure there is an address to generate the CIDR from
		if initConfig.VIPSubnet == "" && initConfig.Address != "" {
			initConfig.VIPSubnet, err = GenerateCidrRange(initConfig.Address, initConfig.DNSMode)
			if err != nil {
				log.Error("generating VIPSubnet", "err", err)
				return
			}
		}

		cfg, err := kubevip.GeneratePodManifestFromConfig(&initConfig, image, Release.Version, inCluster)
		if err != nil {
			log.Error("unable to create manifest", "err", err)
			return
		}
		fmt.Println(cfg) // output manifest to stdout
	},
}