core: Allow "." character in map keys

Fixes #2143 and fixes #7130.

terraform/resource.go

@@ -48,14 +48,6 @@ type Resource struct {
 // its a primary instance, a tainted instance, or an orphan.
 type ResourceFlag byte
 
-const (
-	FlagPrimary ResourceFlag = 1 << iota
-	FlagTainted
-	FlagOrphan
-	FlagReplacePrimary
-	FlagDeposed
-)
-
 // InstanceInfo is used to hold information about the instance and/or
 // resource being modified.
 type InstanceInfo struct {
@@ -180,20 +172,32 @@ func (c *ResourceConfig) get(
 	}
 
 	var current interface{} = raw
-	for _, part := range parts {
+	var previous interface{} = nil
+	for i, part := range parts {
 		if current == nil {
 			return nil, false
 		}
 
 		cv := reflect.ValueOf(current)
 		switch cv.Kind() {
 		case reflect.Map:
+			previous = current
 			v := cv.MapIndex(reflect.ValueOf(part))
 			if !v.IsValid() {
+				if i > 0 && i != (len(parts)-1) {
+					tryKey := strings.Join(parts[i:], ".")
+					v := cv.MapIndex(reflect.ValueOf(tryKey))
+					if !v.IsValid() {
+						return nil, false
+					}
+					return v.Interface(), true
+				}
+
 				return nil, false
 			}
 			current = v.Interface()
 		case reflect.Slice:
+			previous = current
 			if part == "#" {
 				current = cv.Len()
 			} else {
@@ -206,6 +210,14 @@ func (c *ResourceConfig) get(
 				}
 				current = cv.Index(int(i)).Interface()
 			}
+		case reflect.String:
+			// This happens when map keys contain "." and have a common
+			// prefix so were split as path components above.
+			actualKey := strings.Join(parts[i-1:], ".")
+			if prevMap, ok := previous.(map[string]interface{}); ok {
+				return prevMap[actualKey], true
+			}
+			return nil, false
 		default:
 			panic(fmt.Sprintf("Unknown kind: %s", cv.Kind()))
 		}