Fixes #867: save private key when debugging gce builder

Signed-off-by: Prasanna Santhanam <tsp@qubole.com>

builder/googlecompute/builder.go

@@ -5,7 +5,7 @@ package googlecompute
 import (
 	"log"
 	"time"
-
+    "fmt"
 	"github.com/mitchellh/multistep"
 	"github.com/mitchellh/packer/common"
 	"github.com/mitchellh/packer/packer"
@@ -48,21 +48,28 @@ func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) (packe
 	state.Put("ui", ui)
 
 	// Build the steps.
-	steps := []multistep.Step{
-		new(StepCreateSSHKey),
-		new(StepCreateInstance),
-		new(StepInstanceInfo),
-		&common.StepConnectSSH{
-			SSHAddress:     sshAddress,
-			SSHConfig:      sshConfig,
-			SSHWaitTimeout: 5 * time.Minute,
-		},
-		new(common.StepProvision),
-		new(StepUpdateGsutil),
-		new(StepCreateImage),
-		new(StepUploadImage),
-		new(StepRegisterImage),
-	}
+    steps := []multistep.Step{
+      &StepCreateSSHKey{
+        Debug:        b.config.PackerDebug,
+        DebugKeyPath: fmt.Sprintf("gce_%s.pem", b.config.PackerBuildName),
+      },
+      &StepCreateInstance{
+        Debug:        b.config.PackerDebug,
+      },
+      &StepInstanceInfo{
+        Debug:        b.config.PackerDebug,
+      },
+      &common.StepConnectSSH{
+        SSHAddress:     sshAddress,
+        SSHConfig:      sshConfig,
+        SSHWaitTimeout: 5 * time.Minute,
+      },
+      new(common.StepProvision),
+      new(StepUpdateGsutil),
+      new(StepCreateImage),
+      new(StepUploadImage),
+      new(StepRegisterImage),
+    }
 
 	// Run the steps.
 	if b.config.PackerDebug {

builder/googlecompute/step_create_instance.go

@@ -13,6 +13,7 @@ import (
 // StepCreateInstance represents a Packer build step that creates GCE instances.
 type StepCreateInstance struct {
 	instanceName string
+  Debug        bool
 }
 
 // Run executes the Packer build step that creates a GCE instance.
@@ -56,6 +57,12 @@ func (s *StepCreateInstance) Run(state multistep.StateBag) multistep.StepAction
 
 	ui.Message("Instance has been created!")
 
+    if s.Debug {
+      if name != "" {
+        ui.Message(fmt.Sprintf("Instance: %s started in %s", name, config.Zone))
+      }
+    }
+
 	// Things succeeded, store the name so we can remove it later
 	state.Put("instance_name", name)
 	s.instanceName = name

builder/googlecompute/step_create_ssh_key.go

@@ -5,15 +5,19 @@ import (
 	"crypto/rsa"
 	"crypto/x509"
 	"encoding/pem"
+    "os"
 	"fmt"
-
 	"code.google.com/p/go.crypto/ssh"
 	"github.com/mitchellh/multistep"
 	"github.com/mitchellh/packer/packer"
 )
 
 // StepCreateSSHKey represents a Packer build step that generates SSH key pairs.
-type StepCreateSSHKey int
+type StepCreateSSHKey struct {
+  key          int
+  Debug        bool
+  DebugKeyPath string
+}
 
 // Run executes the Packer build step that generates SSH key pairs.
 func (s *StepCreateSSHKey) Run(state multistep.StateBag) multistep.StepAction {
@@ -41,9 +45,20 @@ func (s *StepCreateSSHKey) Run(state multistep.StateBag) multistep.StepAction {
 		ui.Error(err.Error())
 		return multistep.ActionHalt
 	}
+    state.Put("ssh_private_key", string(pem.EncodeToMemory(&priv_blk)))
+    state.Put("ssh_public_key", string(ssh.MarshalAuthorizedKey(pub)))
 
-	state.Put("ssh_private_key", string(pem.EncodeToMemory(&priv_blk)))
-	state.Put("ssh_public_key", string(ssh.MarshalAuthorizedKey(pub)))
+    if s.Debug {
+      ui.Message(fmt.Sprintf("Saving key for debug purposes: %s", s.DebugKeyPath))
+      f, err := os.OpenFile(s.DebugKeyPath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
+      if err != nil {
+        state.Put("error", fmt.Errorf("Error saving debug key: %s", err))
+        return multistep.ActionHalt
+      }
+      // Write out the key
+      pem.Encode(f, &priv_blk)
+      f.Close()
+    }
 	return multistep.ActionContinue
 }
 

builder/googlecompute/step_instance_info.go

@@ -10,7 +10,10 @@ import (
 )
 
 // stepInstanceInfo represents a Packer build step that gathers GCE instance info.
-type StepInstanceInfo int
+type StepInstanceInfo struct {
+  info  int
+  Debug bool
+}
 
 // Run executes the Packer build step that gathers GCE instance info.
 func (s *StepInstanceInfo) Run(state multistep.StateBag) multistep.StepAction {
@@ -44,6 +47,12 @@ func (s *StepInstanceInfo) Run(state multistep.StateBag) multistep.StepAction {
 		return multistep.ActionHalt
 	}
 
+    if s.Debug {
+      if ip != "" {
+        ui.Message(fmt.Sprintf("Public IP: %s", ip))
+      }
+    }
+
 	ui.Message(fmt.Sprintf("IP: %s", ip))
 	state.Put("instance_ip", ip)
 	return multistep.ActionContinue