From 9c612964d82da8dfa17014646b0c76db74450852 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Mon, 23 Feb 2015 14:34:25 -0800
Subject: [PATCH] config: self variables

---
 config/interpolate.go      | 28 ++++++++++++++++++++++++++++
 config/interpolate_test.go |  8 ++++++++
 2 files changed, 36 insertions(+)

diff --git a/config/interpolate.go b/config/interpolate.go
index b13cdb405c..af0a84da49 100644
--- a/config/interpolate.go
+++ b/config/interpolate.go
@@ -68,6 +68,14 @@ type ResourceVariable struct {
 	key string
 }
 
+// SelfVariable is a variable that is referencing the same resource
+// it is running on: "${self.address}"
+type SelfVariable struct {
+	Field string
+
+	key string
+}
+
 // A UserVariable is a variable that is referencing a user variable
 // that is inputted from outside the configuration. This looks like
 // "${var.foo}"
@@ -83,6 +91,8 @@ func NewInterpolatedVariable(v string) (InterpolatedVariable, error) {
 		return NewCountVariable(v)
 	} else if strings.HasPrefix(v, "path.") {
 		return NewPathVariable(v)
+	} else if strings.HasPrefix(v, "self.") {
+		return NewSelfVariable(v)
 	} else if strings.HasPrefix(v, "var.") {
 		return NewUserVariable(v)
 	} else if strings.HasPrefix(v, "module.") {
@@ -199,6 +209,24 @@ func (v *ResourceVariable) FullKey() string {
 	return v.key
 }
 
+func NewSelfVariable(key string) (*SelfVariable, error) {
+	field := key[len("self."):]
+
+	return &SelfVariable{
+		Field: field,
+
+		key: key,
+	}, nil
+}
+
+func (v *SelfVariable) FullKey() string {
+	return v.key
+}
+
+func (v *SelfVariable) GoString() string {
+	return fmt.Sprintf("*%#v", *v)
+}
+
 func NewUserVariable(key string) (*UserVariable, error) {
 	name := key[len("var."):]
 	elem := ""
diff --git a/config/interpolate_test.go b/config/interpolate_test.go
index 46945ee810..69a6ca2293 100644
--- a/config/interpolate_test.go
+++ b/config/interpolate_test.go
@@ -54,6 +54,14 @@ func TestNewInterpolatedVariable(t *testing.T) {
 			},
 			false,
 		},
+		{
+			"self.address",
+			&SelfVariable{
+				Field: "address",
+				key:   "self.address",
+			},
+			false,
+		},
 	}
 
 	for i, tc := range cases {