step_create_ssh_key.go

package scaleway

import (
	"context"
	"crypto/rand"
	"crypto/rsa"
	"crypto/x509"
	"encoding/pem"
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"runtime"
	"strings"

	"github.com/hashicorp/packer/helper/multistep"
	"github.com/hashicorp/packer/packer"
	"golang.org/x/crypto/ssh"
)

type stepCreateSSHKey struct {
	Debug          bool
	DebugKeyPath   string
	PrivateKeyFile string
}

func (s *stepCreateSSHKey) Run(_ context.Context, state multistep.StateBag) multistep.StepAction {
	ui := state.Get("ui").(packer.Ui)

	if s.PrivateKeyFile != "" {
		ui.Say("Using existing SSH private key")
		privateKeyBytes, err := ioutil.ReadFile(s.PrivateKeyFile)
		if err != nil {
			state.Put("error", fmt.Errorf(
				"Error loading configured private key file: %s", err))
			return multistep.ActionHalt
		}

		state.Put("private_key", string(privateKeyBytes))
		state.Put("ssh_pubkey", "")

		return multistep.ActionContinue
	}

	ui.Say("Creating temporary ssh key for server...")

	priv, err := rsa.GenerateKey(rand.Reader, 2014)
	if err != nil {
		err := fmt.Errorf("Error creating temporary SSH key: %s", err)
		state.Put("error", err)
		ui.Error(err.Error())
		return multistep.ActionHalt
	}

	// ASN.1 DER encoded form
	priv_der := x509.MarshalPKCS1PrivateKey(priv)
	priv_blk := pem.Block{
		Type:    "RSA PRIVATE KEY",
		Headers: nil,
		Bytes:   priv_der,
	}

	// Set the private key in the statebag for later
	state.Put("private_key", string(pem.EncodeToMemory(&priv_blk)))

	pub, _ := ssh.NewPublicKey(&priv.PublicKey)
	pub_sshformat := string(ssh.MarshalAuthorizedKey(pub))
	pub_sshformat = strings.Replace(pub_sshformat, " ", "_", -1)

	log.Printf("temporary ssh key created")

	// Remember some state for the future
	state.Put("ssh_pubkey", string(pub_sshformat))

	// If we're in debug mode, output the private key to the working directory.
	if s.Debug {
		ui.Message(fmt.Sprintf("Saving key for debug purposes: %s", s.DebugKeyPath))
		f, err := os.Create(s.DebugKeyPath)
		if err != nil {
			state.Put("error", fmt.Errorf("Error saving debug key: %s", err))
			return multistep.ActionHalt
		}
		defer f.Close()

		// Write the key out
		if _, err := f.Write(pem.EncodeToMemory(&priv_blk)); err != nil {
			state.Put("error", fmt.Errorf("Error saving debug key: %s", err))
			return multistep.ActionHalt
		}

		// Chmod it so that it is SSH ready
		if runtime.GOOS != "windows" {
			if err := f.Chmod(0600); err != nil {
				state.Put("error", fmt.Errorf("Error setting permissions of debug key: %s", err))
				return multistep.ActionHalt
			}
		}
	}

	return multistep.ActionContinue
}

func (s *stepCreateSSHKey) Cleanup(state multistep.StateBag) {
	// SSH key is passed via tag. Nothing to do here.
	return
}