terraform: resource address internal can parse data resource addrs

terraform/resource_address.go

@@ -119,7 +119,19 @@ func parseResourceAddressInternal(s string) (*ResourceAddress, error) {
 	// Split based on ".". Every resource address should have at least two
 	// elements (type and name).
 	parts := strings.Split(s, ".")
-	if len(parts) < 2 || len(parts) > 3 {
+	if len(parts) < 2 || len(parts) > 4 {
+		return nil, fmt.Errorf("Invalid internal resource address format: %s", s)
+	}
+
+	// Data resource if we have at least 3 parts and the first one is data
+	mode := config.ManagedResourceMode
+	if len(parts) > 2 && parts[0] == "data" {
+		mode = config.DataResourceMode
+		parts = parts[1:]
+	}
+
+	// If we're not a data resource and we have more than 3, then it is an error
+	if len(parts) > 3 && mode != config.DataResourceMode {
 		return nil, fmt.Errorf("Invalid internal resource address format: %s", s)
 	}
 
@@ -129,7 +141,7 @@ func parseResourceAddressInternal(s string) (*ResourceAddress, error) {
 		Name:         parts[1],
 		Index:        -1,
 		InstanceType: TypePrimary,
-		Mode:         config.ManagedResourceMode,
+		Mode:         mode,
 	}
 
 	// If we have more parts, then we have an index. Parse that.

terraform/resource_address_test.go

@@ -36,14 +36,47 @@ func TestParseResourceAddressInternal(t *testing.T) {
 			},
 			"aws_instance.foo[1]",
 		},
+
+		"data resource": {
+			"data.aws_ami.foo",
+			&ResourceAddress{
+				Mode:         config.DataResourceMode,
+				Type:         "aws_ami",
+				Name:         "foo",
+				InstanceType: TypePrimary,
+				Index:        -1,
+			},
+			"data.aws_ami.foo",
+		},
+
+		"data resource with count": {
+			"data.aws_ami.foo.1",
+			&ResourceAddress{
+				Mode:         config.DataResourceMode,
+				Type:         "aws_ami",
+				Name:         "foo",
+				InstanceType: TypePrimary,
+				Index:        1,
+			},
+			"data.aws_ami.foo[1]",
+		},
+
+		"non-data resource with 4 elements": {
+			"aws_instance.foo.bar.1",
+			nil,
+			"",
+		},
 	}
 
 	for tn, tc := range cases {
 		t.Run(tc.Input, func(t *testing.T) {
 			out, err := parseResourceAddressInternal(tc.Input)
-			if err != nil {
+			if (err != nil) != (tc.Expected == nil) {
 				t.Fatalf("%s: unexpected err: %#v", tn, err)
 			}
+			if err != nil {
+				return
+			}
 
 			if !reflect.DeepEqual(out, tc.Expected) {
 				t.Fatalf("bad: %q\n\nexpected:\n%#v\n\ngot:\n%#v", tn, tc.Expected, out)