kat/internal/cli/join.go

package cli

import (
	"bytes"
	"crypto/tls"
	"crypto/x509"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"time"

	"git.dws.rip/dubey/kat/internal/pki"
)

// JoinRequest represents the data sent to the leader when joining
type JoinRequest struct {
	NodeName        string `json:"nodeName"`
	AdvertiseAddr   string `json:"advertiseAddr"`
	CSRData         string `json:"csrData"` // base64 encoded CSR
	WireGuardPubKey string `json:"wireguardPubKey"`
}

// JoinResponse represents the data received from the leader after a successful join
type JoinResponse struct {
	NodeName             string `json:"nodeName"`
	NodeUID              string `json:"nodeUID"`
	SignedCertificate    string `json:"signedCertificate"` // base64 encoded certificate
	CACertificate        string `json:"caCertificate"`     // base64 encoded CA certificate
	AssignedSubnet       string `json:"assignedSubnet"`
	EtcdJoinInstructions string `json:"etcdJoinInstructions,omitempty"`
}

// JoinCluster sends a join request to the leader and processes the response
func JoinCluster(leaderAPI, advertiseAddr, nodeName, leaderCACert string, pkiDir string) error {
	// Create PKI directory if it doesn't exist
	if err := os.MkdirAll(pkiDir, 0700); err != nil {
		return fmt.Errorf("failed to create PKI directory: %w", err)
	}

	// Generate key and CSR
	nodeKeyPath := filepath.Join(pkiDir, "node.key")
	nodeCSRPath := filepath.Join(pkiDir, "node.csr")
	nodeCertPath := filepath.Join(pkiDir, "node.crt")
	caCertPath := filepath.Join(pkiDir, "ca.crt")

	log.Printf("Generating node key and CSR...")
	if err := pki.GenerateCertificateRequest(nodeName, nodeKeyPath, nodeCSRPath); err != nil {
		return fmt.Errorf("failed to generate key and CSR: %w", err)
	}

	// Read the CSR file
	csrData, err := os.ReadFile(nodeCSRPath)
	if err != nil {
		return fmt.Errorf("failed to read CSR file: %w", err)
	}

	// Create join request
	joinReq := JoinRequest{
		NodeName:        nodeName,
		AdvertiseAddr:   advertiseAddr,
		CSRData:         base64.StdEncoding.EncodeToString(csrData),
		WireGuardPubKey: "placeholder", // Will be implemented in a future phase
	}

	// Marshal request to JSON
	reqBody, err := json.Marshal(joinReq)
	if err != nil {
		return fmt.Errorf("failed to marshal join request: %w", err)
	}

	// Create HTTP client with TLS configuration
	client := &http.Client{
		Timeout: 30 * time.Second,
	}

	// If leader CA cert is provided, configure TLS to trust it
	if leaderCACert != "" {
		// Read the CA cert file
		caCert, err := os.ReadFile(leaderCACert)
		if err != nil {
			return fmt.Errorf("failed to read leader CA certificate: %w", err)
		}

		// Create a cert pool and add the CA cert
		caCertPool := x509.NewCertPool()
		if !caCertPool.AppendCertsFromPEM(caCert) {
			return fmt.Errorf("failed to parse leader CA certificate")
		}

		// Configure TLS
		client.Transport = &http.Transport{
			TLSClientConfig: &tls.Config{
				RootCAs: caCertPool,
			},
		}
	} else {
		// For development/testing, allow insecure connections
		// This should be removed in production
		log.Println("WARNING: No leader CA certificate provided. TLS verification disabled.")
		client.Transport = &http.Transport{
			TLSClientConfig: &tls.Config{
				InsecureSkipVerify: true,
			},
		}
	}

	// Send join request to leader
	joinURL := fmt.Sprintf("https://%s/internal/v1alpha1/join", leaderAPI)
	log.Printf("Sending join request to %s...", joinURL)
	resp, err := client.Post(joinURL, "application/json", bytes.NewBuffer(reqBody))
	if err != nil {
		return fmt.Errorf("failed to send join request: %w", err)
	}
	defer resp.Body.Close()

	// Read response body
	respBody, err := io.ReadAll(resp.Body)
	if err != nil {
		return fmt.Errorf("failed to read response body: %w", err)
	}

	// Check response status
	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("join request failed with status %d: %s", resp.StatusCode, string(respBody))
	}

	// Parse response
	var joinResp JoinResponse
	if err := json.Unmarshal(respBody, &joinResp); err != nil {
		return fmt.Errorf("failed to parse join response: %w", err)
	}

	// Save signed certificate
	certData, err := base64.StdEncoding.DecodeString(joinResp.SignedCertificate)
	if err != nil {
		return fmt.Errorf("failed to decode signed certificate: %w", err)
	}
	if err := os.WriteFile(nodeCertPath, certData, 0600); err != nil {
		return fmt.Errorf("failed to save signed certificate: %w", err)
	}
	log.Printf("Saved signed certificate to %s", nodeCertPath)

	// Save CA certificate
	caCertData, err := base64.StdEncoding.DecodeString(joinResp.CACertificate)
	if err != nil {
		return fmt.Errorf("failed to decode CA certificate: %w", err)
	}
	if err := os.WriteFile(caCertPath, caCertData, 0600); err != nil {
		return fmt.Errorf("failed to save CA certificate: %w", err)
	}
	log.Printf("Saved CA certificate to %s", caCertPath)

	log.Printf("Successfully joined cluster as node: %s", joinResp.NodeName)
	if joinResp.AssignedSubnet != "" {
		log.Printf("Assigned subnet: %s", joinResp.AssignedSubnet)
	}
	if joinResp.EtcdJoinInstructions != "" {
		log.Printf("Etcd join instructions: %s", joinResp.EtcdJoinInstructions)
	}

	return nil
}