terraform: InstanceState.Meta is value type interface{}

This changes the type of values in Meta for InstanceState to
`interface{}`. They were `string` before.

This will allow richer structures to be persisted to this without
flatmapping them (down with flatmap!). The documentation clearly states
that only primitives/collections are allowed here.

The only thing using this was helper/schema for schema versioning.
Appropriate type checking was added to make this change safe.

The timeout work @catsby is doing will use this for a richer structure.

helper/schema/resource.go

@@ -353,7 +353,7 @@ func (r *Resource) Data(s *terraform.InstanceState) *ResourceData {
 	}
 
 	// Set the schema version to latest by default
-	result.meta = map[string]string{
+	result.meta = map[string]interface{}{
 		"schema_version": strconv.Itoa(r.SchemaVersion),
 	}
 
@@ -378,7 +378,22 @@ func (r *Resource) isTopLevel() bool {
 // Determines if a given InstanceState needs to be migrated by checking the
 // stored version number with the current SchemaVersion
 func (r *Resource) checkSchemaVersion(is *terraform.InstanceState) (bool, int) {
-	stateSchemaVersion, _ := strconv.Atoi(is.Meta["schema_version"])
+	// Get the raw interface{} value for the schema version. If it doesn't
+	// exist or is nil then set it to zero.
+	raw := is.Meta["schema_version"]
+	if raw == nil {
+		raw = "0"
+	}
+
+	// Try to convert it to a string. If it isn't a string then we pretend
+	// that it isn't set at all. It should never not be a string unless it
+	// was manually tampered with.
+	rawString, ok := raw.(string)
+	if !ok {
+		rawString = "0"
+	}
+
+	stateSchemaVersion, _ := strconv.Atoi(rawString)
 	return stateSchemaVersion < r.SchemaVersion, stateSchemaVersion
 }
 
@@ -386,7 +401,7 @@ func (r *Resource) recordCurrentSchemaVersion(
 	state *terraform.InstanceState) *terraform.InstanceState {
 	if state != nil && r.SchemaVersion > 0 {
 		if state.Meta == nil {
-			state.Meta = make(map[string]string)
+			state.Meta = make(map[string]interface{})
 		}
 		state.Meta["schema_version"] = strconv.Itoa(r.SchemaVersion)
 	}

helper/schema/resource_data.go

@@ -23,7 +23,7 @@ type ResourceData struct {
 	config *terraform.ResourceConfig
 	state  *terraform.InstanceState
 	diff   *terraform.InstanceDiff
-	meta   map[string]string
+	meta   map[string]interface{}
 
 	// Don't set
 	multiReader *MultiLevelFieldReader

helper/schema/resource_test.go

@@ -52,7 +52,7 @@ func TestResourceApply_create(t *testing.T) {
 			"id":  "foo",
 			"foo": "42",
 		},
-		Meta: map[string]string{
+		Meta: map[string]interface{}{
 			"schema_version": "2",
 		},
 	}
@@ -210,7 +210,7 @@ func TestResourceApply_destroyPartial(t *testing.T) {
 			"id":  "bar",
 			"foo": "42",
 		},
-		Meta: map[string]string{
+		Meta: map[string]interface{}{
 			"schema_version": "3",
 		},
 	}
@@ -558,7 +558,7 @@ func TestResourceRefresh(t *testing.T) {
 			"id":  "bar",
 			"foo": "13",
 		},
-		Meta: map[string]string{
+		Meta: map[string]interface{}{
 			"schema_version": "2",
 		},
 	}
@@ -749,7 +749,7 @@ func TestResourceRefresh_needsMigration(t *testing.T) {
 		Attributes: map[string]string{
 			"oldfoo": "1.2",
 		},
-		Meta: map[string]string{
+		Meta: map[string]interface{}{
 			"schema_version": "1",
 		},
 	}
@@ -765,7 +765,7 @@ func TestResourceRefresh_needsMigration(t *testing.T) {
 			"id":     "bar",
 			"newfoo": "13",
 		},
-		Meta: map[string]string{
+		Meta: map[string]interface{}{
 			"schema_version": "2",
 		},
 	}
@@ -803,7 +803,7 @@ func TestResourceRefresh_noMigrationNeeded(t *testing.T) {
 		Attributes: map[string]string{
 			"newfoo": "12",
 		},
-		Meta: map[string]string{
+		Meta: map[string]interface{}{
 			"schema_version": "2",
 		},
 	}
@@ -819,7 +819,7 @@ func TestResourceRefresh_noMigrationNeeded(t *testing.T) {
 			"id":     "bar",
 			"newfoo": "13",
 		},
-		Meta: map[string]string{
+		Meta: map[string]interface{}{
 			"schema_version": "2",
 		},
 	}
@@ -871,7 +871,7 @@ func TestResourceRefresh_stateSchemaVersionUnset(t *testing.T) {
 			"id":     "bar",
 			"newfoo": "13",
 		},
-		Meta: map[string]string{
+		Meta: map[string]interface{}{
 			"schema_version": "1",
 		},
 	}
@@ -945,7 +945,7 @@ func TestResourceData(t *testing.T) {
 	}
 
 	// Set expectations
-	state.Meta = map[string]string{
+	state.Meta = map[string]interface{}{
 		"schema_version": "2",
 	}
 

terraform/state.go

@@ -1541,8 +1541,9 @@ type InstanceState struct {
 
 	// Meta is a simple K/V map that is persisted to the State but otherwise
 	// ignored by Terraform core. It's meant to be used for accounting by
-	// external client code.
+	// external client code. The value here must only contain Go primitives
-	Meta map[string]string `json:"meta"`
+	// and collections.
+	Meta map[string]interface{} `json:"meta"`
 
 	// Tainted is used to mark a resource for recreation.
 	Tainted bool `json:"tainted"`
@@ -1561,7 +1562,7 @@ func (s *InstanceState) init() {
 		s.Attributes = make(map[string]string)
 	}
 	if s.Meta == nil {
-		s.Meta = make(map[string]string)
+		s.Meta = make(map[string]interface{})
 	}
 	s.Ephemeral.init()
 }

terraform/state_test.go

@@ -278,7 +278,7 @@ func TestStateDeepCopy(t *testing.T) {
 						Resources: map[string]*ResourceState{
 							"test_instance.foo": &ResourceState{
 								Primary: &InstanceState{
-									Meta: map[string]string{},
+									Meta: map[string]interface{}{},
 								},
 							},
 						},
@@ -298,7 +298,7 @@ func TestStateDeepCopy(t *testing.T) {
 						Resources: map[string]*ResourceState{
 							"test_instance.foo": &ResourceState{
 								Primary: &InstanceState{
-									Meta: map[string]string{},
+									Meta: map[string]interface{}{},
 								},
 								Deposed: []*InstanceState{
 									{ID: "test"},
@@ -389,7 +389,7 @@ func TestStateEqual(t *testing.T) {
 						Resources: map[string]*ResourceState{
 							"test_instance.foo": &ResourceState{
 								Primary: &InstanceState{
-									Meta: map[string]string{
+									Meta: map[string]interface{}{
 										"schema_version": "1",
 									},
 								},
@@ -405,7 +405,7 @@ func TestStateEqual(t *testing.T) {
 						Resources: map[string]*ResourceState{
 							"test_instance.foo": &ResourceState{
 								Primary: &InstanceState{
-									Meta: map[string]string{
+									Meta: map[string]interface{}{
 										"schema_version": "2",
 									},
 								},
@@ -610,7 +610,7 @@ func TestStateIncrementSerialMaybe(t *testing.T) {
 						Resources: map[string]*ResourceState{
 							"test_instance.foo": &ResourceState{
 								Primary: &InstanceState{
-									Meta: map[string]string{},
+									Meta: map[string]interface{}{},
 								},
 							},
 						},
@@ -625,7 +625,7 @@ func TestStateIncrementSerialMaybe(t *testing.T) {
 						Resources: map[string]*ResourceState{
 							"test_instance.foo": &ResourceState{
 								Primary: &InstanceState{
-									Meta: map[string]string{
+									Meta: map[string]interface{}{
 										"schema_version": "1",
 									},
 								},

terraform/state_upgrade_v1_to_v2.go

@@ -150,16 +150,22 @@ func (old *instanceStateV1) upgradeToV2() (*InstanceState, error) {
 	if err != nil {
 		return nil, fmt.Errorf("Error upgrading InstanceState V1: %v", err)
 	}
+
 	meta, err := copystructure.Copy(old.Meta)
 	if err != nil {
 		return nil, fmt.Errorf("Error upgrading InstanceState V1: %v", err)
 	}
 
+	newMeta := make(map[string]interface{})
+	for k, v := range meta.(map[string]string) {
+		newMeta[k] = v
+	}
+
 	return &InstanceState{
 		ID:         old.ID,
 		Attributes: attributes.(map[string]string),
 		Ephemeral:  *ephemeral,
-		Meta:       meta.(map[string]string),
+		Meta:       newMeta,
 	}, nil
 }