Save the generated SSH key as a file in debug mode

builder/digitalocean/builder.go

@@ -244,7 +244,10 @@ func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) (packe
 
 	// Build the steps
 	steps := []multistep.Step{
-		new(stepCreateSSHKey),
+		&stepCreateSSHKey{
+			Debug: b.config.PackerDebug,
+			DebugKeyPath: fmt.Sprintf("do_%s.pem", b.config.PackerBuildName),
+		},
 		new(stepCreateDroplet),
 		new(stepDropletInfo),
 		&common.StepConnectSSH{

builder/digitalocean/step_create_ssh_key.go

@@ -7,6 +7,8 @@ import (
 	"encoding/pem"
 	"fmt"
 	"log"
+	"runtime"
+	"os"
 
 	"code.google.com/p/gosshold/ssh"
 	"github.com/mitchellh/multistep"
@@ -15,7 +17,9 @@ import (
 )
 
 type stepCreateSSHKey struct {
-	keyId uint
+	Debug        bool
+	DebugKeyPath string
+	keyId        uint
 }
 
 func (s *stepCreateSSHKey) Run(state multistep.StateBag) multistep.StepAction {
@@ -62,6 +66,31 @@ func (s *stepCreateSSHKey) Run(state multistep.StateBag) multistep.StepAction {
 	// Remember some state for the future
 	state.Put("ssh_key_id", keyId)
 
+	// 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
 }