Add existing SSH key support

Update documentation

builder/scaleway/builder.go

@@ -45,6 +45,7 @@ func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) (packe
 		&stepCreateSSHKey{
 			Debug:          b.config.PackerDebug,
 			DebugKeyPath:   fmt.Sprintf("scw_%s.pem", b.config.PackerBuildName),
+			PrivateKeyFile: b.config.Comm.SSHPrivateKey,
 		},
 		new(stepCreateServer),
 		new(stepServerInfo),

builder/scaleway/step_create_server.go

@@ -18,15 +18,20 @@ func (s *stepCreateServer) Run(state multistep.StateBag) multistep.StepAction {
 	ui := state.Get("ui").(packer.Ui)
 	c := state.Get("config").(Config)
 	sshPubKey := state.Get("ssh_pubkey").(string)
+	tags := []string{}
 
 	ui.Say("Creating server...")
 
+	if sshPubKey != "" {
+		tags = []string{fmt.Sprintf("AUTHORIZED_KEY=%s", strings.TrimSpace(sshPubKey))}
+	}
+
 	server, err := client.PostServer(api.ScalewayServerDefinition{
 		Name:           c.ServerName,
 		Image:          &c.Image,
 		Organization:   c.Organization,
 		CommercialType: c.CommercialType,
-		Tags:           []string{fmt.Sprintf("AUTHORIZED_KEY=%s", strings.TrimSpace(sshPubKey))},
+		Tags:           tags,
 	})
 
 	err = client.PostServerAction(server, "poweron")

builder/scaleway/step_create_ssh_key.go

@@ -6,6 +6,7 @@ import (
 	"crypto/x509"
 	"encoding/pem"
 	"fmt"
+	"io/ioutil"
 	"log"
 	"os"
 	"runtime"
@@ -19,11 +20,27 @@ import (
 type stepCreateSSHKey struct {
 	Debug          bool
 	DebugKeyPath   string
+	PrivateKeyFile string
 }
 
 func (s *stepCreateSSHKey) Run(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("privateKey", string(privateKeyBytes))
+		state.Put("ssh_pubkey", "")
+
+		return multistep.ActionContinue
+	}
+
 	ui.Say("Creating temporary ssh key for server...")
 
 	priv, err := rsa.GenerateKey(rand.Reader, 2014)

website/source/docs/builders/scaleway.html.md

@@ -68,6 +68,8 @@ builder.
 - `snapshot_name` (string) - The name of the resulting snapshot that will
     appear in your account.
 
+- `ssh_private_key_file` (string) - Path to a PEM encoded private key file to use to authentiate with SSH.
+
 ## Basic Example
 
 Here is a basic example. It is completely valid as soon as you enter your own
@@ -81,6 +83,10 @@ access tokens:
   "image": "f01f8a48-c026-48ac-9771-a70eaac0890e",
   "region": "par1",
   "commercial_type": "X64-2GB",
-  "ssh_username": "root"
+  "ssh_username": "root",
+  "ssh_private_key_file": "~/.ssh/id_rsa",
 }
 ```
+
+When you do not specified the `ssh_private_key_file`, a temporarily SSH keypair is generated to connect the server.
+This key will only allows the `root` user to connect the server.