builder/digitalocean: send a "shutdown" before snapshotting

Instead of pulling the plug on a droplet with the "poweroff" command,
we first send a soft shutdown to the API, then we poweroff to allow
the snapshot to properly complete.

Sending just a shutdown and then snapshotting wasn't as reliable as
sending the poweroff manually, for reasons unknown to me.

This fixes #332.

builder/digitalocean/api.go

@@ -115,6 +115,15 @@ func (d DigitalOceanClient) PowerOffDroplet(id uint) error {
 	return err
 }
 
+// Shutsdown a droplet. This is a "soft" shutdown.
+func (d DigitalOceanClient) ShutdownDroplet(id uint) error {
+	path := fmt.Sprintf("droplets/%v/shutdown", id)
+
+	_, err := NewRequest(d, path, url.Values{})
+
+	return err
+}
+
 // Creates a snaphot of a droplet by it's ID
 func (d DigitalOceanClient) CreateSnapshot(id uint, name string) error {
 	path := fmt.Sprintf("droplets/%v/snapshot", id)

builder/digitalocean/builder.go

@@ -206,6 +206,7 @@ func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) (packe
 			SSHWaitTimeout: 5 * time.Minute,
 		},
 		new(common.StepProvision),
+		new(stepShutdown),
 		new(stepPowerOff),
 		new(stepSnapshot),
 	}

builder/digitalocean/step_power_off.go

@@ -32,15 +32,14 @@ func (s *stepPowerOff) Run(state map[string]interface{}) multistep.StepAction {
 		return multistep.ActionHalt
 	}
 
-	ui.Say("Waiting for droplet to power off...")
+	log.Println("Waiting for poweroff event to complete...")
 
-	err = waitForDropletState("off", dropletId, client, c)
-	if err != nil {
-		err := fmt.Errorf("Error waiting for droplet to become 'off': %s", err)
-		state["error"] = err
-		ui.Error(err.Error())
-		return multistep.ActionHalt
-	}
+	// This arbitrary sleep is because we can't wait for the state
+	// of the droplet to be 'off', as stepShutdown should already
+	// have accomplished that, and the state indicator is the same.
+	// We just have to assume that this event will process quickly.
+	log.Printf("Sleeping for %v, event_delay", c.RawEventDelay)
+	time.Sleep(c.eventDelay)
 
 	return multistep.ActionContinue
 }

builder/digitalocean/step_shutdown.go

+package digitalocean
+
+import (
+	"fmt"
+	"github.com/mitchellh/multistep"
+	"github.com/mitchellh/packer/packer"
+	"log"
+	"time"
+)
+
+type stepShutdown struct{}
+
+func (s *stepShutdown) Run(state map[string]interface{}) multistep.StepAction {
+	client := state["client"].(*DigitalOceanClient)
+	c := state["config"].(config)
+	ui := state["ui"].(packer.Ui)
+	dropletId := state["droplet_id"].(uint)
+
+	// Sleep arbitrarily before sending the request
+	// Otherwise we get "pending event" errors, even though there isn't
+	// one.
+	log.Printf("Sleeping for %v, event_delay", c.RawEventDelay)
+	time.Sleep(c.eventDelay)
+
+	err := client.ShutdownDroplet(dropletId)
+
+	if err != nil {
+		err := fmt.Errorf("Error shutting down droplet: %s", err)
+		state["error"] = err
+		ui.Error(err.Error())
+		return multistep.ActionHalt
+	}
+
+	ui.Say("Waiting for droplet to shutdown...")
+
+	err = waitForDropletState("off", dropletId, client, c)
+	if err != nil {
+		err := fmt.Errorf("Error waiting for droplet to become 'off': %s", err)
+		state["error"] = err
+		ui.Error(err.Error())
+		return multistep.ActionHalt
+	}
+
+	return multistep.ActionContinue
+}
+
+func (s *stepShutdown) Cleanup(state map[string]interface{}) {
+	// no cleanup
+}