From 05c0998d2d84d7b06743761e9858a17470935cdb Mon Sep 17 00:00:00 2001
From: Paul Hinze <phinze@phinze.com>
Date: Tue, 20 Oct 2015 14:33:28 -0500
Subject: [PATCH] core: store deeply nested modules in a consistent order in
 the state

We were only comparing the last element of the module, which meant that
deeply nested modules with the same name but different ancestry had an
undefined sort order, which could cause inconsistencies in state
storage and potentially break remote state MD5 checksumming.
---
 terraform/state.go      |  5 ++---
 terraform/state_test.go | 17 +++++++++++++++++
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/terraform/state.go b/terraform/state.go
index e97e0c27c..8734cfc17 100644
--- a/terraform/state.go
+++ b/terraform/state.go
@@ -1207,9 +1207,8 @@ func (s moduleStateSort) Less(i, j int) bool {
 		return len(a.Path) < len(b.Path)
 	}
 
-	// Otherwise, compare by last path element
-	idx := len(a.Path) - 1
-	return a.Path[idx] < b.Path[idx]
+	// Otherwise, compare lexically
+	return strings.Join(a.Path, ".") < strings.Join(b.Path, ".")
 }
 
 func (s moduleStateSort) Swap(i, j int) {
diff --git a/terraform/state_test.go b/terraform/state_test.go
index cc7b91bbc..8d24a8e75 100644
--- a/terraform/state_test.go
+++ b/terraform/state_test.go
@@ -40,6 +40,23 @@ func TestStateAddModule(t *testing.T) {
 				[]string{"root", "foo", "bar"},
 			},
 		},
+		// Same last element, different middle element
+		{
+			[][]string{
+				[]string{"root", "foo", "bar"}, // This one should sort after...
+				[]string{"root", "foo"},
+				[]string{"root"},
+				[]string{"root", "bar", "bar"}, // ...this one.
+				[]string{"root", "bar"},
+			},
+			[][]string{
+				[]string{"root"},
+				[]string{"root", "bar"},
+				[]string{"root", "foo"},
+				[]string{"root", "bar", "bar"},
+				[]string{"root", "foo", "bar"},
+			},
+		},
 	}
 
 	for _, tc := range cases {