Use a GOPATH workspace format

.gitignore

@@ -1 +1 @@
-/packer
+/bin

example.json

@@ -0,0 +1,9 @@
+{
+    "name": "ubuntu-12.04.2-server-amd64",
+
+    "builders": [
+        "virtualbox": {
+            "os_type": "Ubuntu_64",
+        }
+    ]
+}

src/packer/bin-packer/main.go

@@ -1,8 +1,12 @@
 // This is the main package for the `packer` application.
 package main
 
-import "fmt"
+import (
+	"fmt"
+	"os"
+)
 
 func main() {
+	fmt.Printf("%#v\n", os.Args)
 	fmt.Println("Hello, world.")
 }