From 69759e04ca40b25b3dcc084e3888fc011c9e0f9e Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Tue, 21 Mar 2017 11:37:12 -0700
Subject: [PATCH] terraform: convert empty path to root path in V1 state

---
 terraform/state_upgrade_v1_to_v2.go           | 10 +++--
 terraform/state_upgrade_v1_to_v2_test.go      | 22 +++++++++++
 .../state-upgrade/v1-to-v2-empty-path.tfstate | 38 +++++++++++++++++++
 3 files changed, 67 insertions(+), 3 deletions(-)
 create mode 100644 terraform/state_upgrade_v1_to_v2_test.go
 create mode 100644 terraform/test-fixtures/state-upgrade/v1-to-v2-empty-path.tfstate

diff --git a/terraform/state_upgrade_v1_to_v2.go b/terraform/state_upgrade_v1_to_v2.go
index 88192e87e..aa13cce80 100644
--- a/terraform/state_upgrade_v1_to_v2.go
+++ b/terraform/state_upgrade_v1_to_v2.go
@@ -64,11 +64,15 @@ func (old *moduleStateV1) upgradeToV2() (*ModuleState, error) {
 		return nil, nil
 	}
 
-	path, err := copystructure.Copy(old.Path)
+	pathRaw, err := copystructure.Copy(old.Path)
 	if err != nil {
 		return nil, fmt.Errorf("Error upgrading ModuleState V1: %v", err)
 	}
-	if path == nil {
+	path, ok := pathRaw.([]string)
+	if !ok {
+		return nil, fmt.Errorf("Error upgrading ModuleState V1: path is not a list of strings")
+	}
+	if len(path) == 0 {
 		// We found some V1 states with a nil path. Assume root and catch
 		// duplicate path errors later (as part of Validate).
 		path = rootModulePath
@@ -99,7 +103,7 @@ func (old *moduleStateV1) upgradeToV2() (*ModuleState, error) {
 	}
 
 	return &ModuleState{
-		Path:         path.([]string),
+		Path:         path,
 		Outputs:      outputs,
 		Resources:    resources,
 		Dependencies: dependencies.([]string),
diff --git a/terraform/state_upgrade_v1_to_v2_test.go b/terraform/state_upgrade_v1_to_v2_test.go
new file mode 100644
index 000000000..a660ae898
--- /dev/null
+++ b/terraform/state_upgrade_v1_to_v2_test.go
@@ -0,0 +1,22 @@
+package terraform
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestReadStateV1ToV2_noPath(t *testing.T) {
+	f, err := os.Open(filepath.Join(fixtureDir, "state-upgrade", "v1-to-v2-empty-path.tfstate"))
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	defer f.Close()
+
+	s, err := ReadState(f)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	checkStateString(t, s, "<no state>")
+}
diff --git a/terraform/test-fixtures/state-upgrade/v1-to-v2-empty-path.tfstate b/terraform/test-fixtures/state-upgrade/v1-to-v2-empty-path.tfstate
new file mode 100644
index 000000000..ee7c9d187
--- /dev/null
+++ b/terraform/test-fixtures/state-upgrade/v1-to-v2-empty-path.tfstate
@@ -0,0 +1,38 @@
+{
+    "version": 1,
+    "modules": [{
+        "resources": {
+            "aws_instance.foo1": {"primary":{}},
+            "cloudstack_instance.foo1": {"primary":{}},
+            "cloudstack_instance.foo2": {"primary":{}},
+            "digitalocean_droplet.foo1": {"primary":{}},
+            "digitalocean_droplet.foo2": {"primary":{}},
+            "digitalocean_droplet.foo3": {"primary":{}},
+            "docker_container.foo1": {"primary":{}},
+            "docker_container.foo2": {"primary":{}},
+            "docker_container.foo3": {"primary":{}},
+            "docker_container.foo4": {"primary":{}},
+            "google_compute_instance.foo1": {"primary":{}},
+            "google_compute_instance.foo2": {"primary":{}},
+            "google_compute_instance.foo3": {"primary":{}},
+            "google_compute_instance.foo4": {"primary":{}},
+            "google_compute_instance.foo5": {"primary":{}},
+            "heroku_app.foo1": {"primary":{}},
+            "heroku_app.foo2": {"primary":{}},
+            "heroku_app.foo3": {"primary":{}},
+            "heroku_app.foo4": {"primary":{}},
+            "heroku_app.foo5": {"primary":{}},
+            "heroku_app.foo6": {"primary":{}},
+            "openstack_compute_instance_v2.foo1": {"primary":{}},
+            "openstack_compute_instance_v2.foo2": {"primary":{}},
+            "openstack_compute_instance_v2.foo3": {"primary":{}},
+            "openstack_compute_instance_v2.foo4": {"primary":{}},
+            "openstack_compute_instance_v2.foo5": {"primary":{}},
+            "openstack_compute_instance_v2.foo6": {"primary":{}},
+            "openstack_compute_instance_v2.foo7": {"primary":{}},
+            "bar": {"primary":{}},
+            "baz": {"primary":{}},
+            "zip": {"primary":{}}
+        }
+    }]
+}