Merge pull request #12944 from hashicorp/jbardin/GH-12919

restructure JSON terraform config block AST

config/loader_hcl.go

@@ -209,6 +209,19 @@ func loadTerraformHcl(list *ast.ObjectList) (*Terraform, error) {
 	// Get our one item
 	item := list.Items[0]
 
+	// This block should have an empty top level ObjectItem.  If there are keys
+	// here, it's likely because we have a flattened JSON object, and we can
+	// lift this into a nested ObjectList to decode properly.
+	if len(item.Keys) > 0 {
+		item = &ast.ObjectItem{
+			Val: &ast.ObjectType{
+				List: &ast.ObjectList{
+					Items: []*ast.ObjectItem{item},
+				},
+			},
+		}
+	}
+
 	// We need the item value as an ObjectList
 	var listVal *ast.ObjectList
 	if ot, ok := item.Val.(*ast.ObjectType); ok {

config/loader_test.go

@@ -384,6 +384,32 @@ backend (s3)
 	}
 }
 
+// test that the alternate, more obvious JSON format also decodes properly
+func TestLoadFile_terraformBackendJSON2(t *testing.T) {
+	c, err := LoadFile(filepath.Join(fixtureDir, "terraform-backend-2.tf.json"))
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	if c == nil {
+		t.Fatal("config should not be nil")
+	}
+
+	if c.Dir != "" {
+		t.Fatalf("bad: %#v", c.Dir)
+	}
+
+	{
+		actual := terraformStr(c.Terraform)
+		expected := strings.TrimSpace(`
+backend (s3)
+  foo`)
+		if actual != expected {
+			t.Fatalf("bad:\n%s", actual)
+		}
+	}
+}
+
 func TestLoadFile_terraformBackendMulti(t *testing.T) {
 	_, err := LoadFile(filepath.Join(fixtureDir, "terraform-backend-multi.tf"))
 	if err == nil {

config/test-fixtures/terraform-backend-2.tf.json

@@ -0,0 +1,9 @@
+{
+  "terraform": {
+    "backend": {
+      "s3": {
+        "foo": "bar"
+      }
+    }
+  }
+}