builder/amazonebs: interpolate create time into AMI name

builder/amazonebs/step_create_ami.go

 package amazonebs
 
 import (
+	"bytes"
 	"fmt"
 	"github.com/mitchellh/goamz/ec2"
 	"github.com/mitchellh/multistep"
 	"github.com/mitchellh/packer/packer"
+	"text/template"
+	"time"
 )
 
 type stepCreateAMI struct{}
 
+type amiNameData struct {
+	CreateTime string
+}
+
 func (s *stepCreateAMI) Run(state map[string]interface{}) multistep.StepAction {
 	config := state["config"].(config)
 	ec2conn := state["ec2"].(*ec2.EC2)
 	instance := state["instance"].(*ec2.Instance)
 	ui := state["ui"].(packer.Ui)
 
+	// Parse the name of the AMI
+	amiNameBuf := new(bytes.Buffer)
+	tData := amiNameData{
+		time.Now().UTC().String(),
+	}
+
+	t := template.Must(template.New("ami").Parse(config.AMIName))
+	t.Execute(amiNameBuf, tData)
+	amiName := amiNameBuf.String()
+
 	// Create the image
-	ui.Say("Creating the AMI...")
+	ui.Say(fmt.Sprintf("Creating the AMI: %s", amiName))
 	createOpts := &ec2.CreateImage{
 		InstanceId: instance.InstanceId,
-		Name:       config.AMIName,
+		Name:       amiName,
 	}
 
 	createResp, err := ec2conn.CreateImage(createOpts)