From 7c8bbd6bcb53742ec33fd1533dc0d5469731b3d1 Mon Sep 17 00:00:00 2001
From: Max Neverov <1296281+mneverov@users.noreply.github.com>
Date: Wed, 12 Aug 2020 23:37:31 +0200
Subject: [PATCH] Add fmt rule check: labels with the name __name__ are invalid
 (#7787)

Signed-off-by: Max Neverov <neverov.max@gmail.com>
---
 pkg/rulefmt/rulefmt.go                           | 2 +-
 pkg/rulefmt/rulefmt_test.go                      | 4 ++++
 pkg/rulefmt/testdata/invalid_label_name.bad.yaml | 7 +++++++
 3 files changed, 12 insertions(+), 1 deletion(-)
 create mode 100644 pkg/rulefmt/testdata/invalid_label_name.bad.yaml

diff --git a/pkg/rulefmt/rulefmt.go b/pkg/rulefmt/rulefmt.go
index 7a2179e7d..8267bc90e 100644
--- a/pkg/rulefmt/rulefmt.go
+++ b/pkg/rulefmt/rulefmt.go
@@ -186,7 +186,7 @@ func (r *RuleNode) Validate() (nodes []WrappedError) {
 	}
 
 	for k, v := range r.Labels {
-		if !model.LabelName(k).IsValid() {
+		if !model.LabelName(k).IsValid() || k == model.MetricNameLabel {
 			nodes = append(nodes, WrappedError{
 				err: errors.Errorf("invalid label name: %s", k),
 			})
diff --git a/pkg/rulefmt/rulefmt_test.go b/pkg/rulefmt/rulefmt_test.go
index 4101b61b9..92967cf7d 100644
--- a/pkg/rulefmt/rulefmt_test.go
+++ b/pkg/rulefmt/rulefmt_test.go
@@ -71,6 +71,10 @@ func TestParseFileFailure(t *testing.T) {
 			filename: "bad_field.bad.yaml",
 			errMsg:   "field annotation not found",
 		},
+		{
+			filename: "invalid_label_name.bad.yaml",
+			errMsg:   "invalid label name",
+		},
 	}
 
 	for _, c := range table {
diff --git a/pkg/rulefmt/testdata/invalid_label_name.bad.yaml b/pkg/rulefmt/testdata/invalid_label_name.bad.yaml
new file mode 100644
index 000000000..72f69faa9
--- /dev/null
+++ b/pkg/rulefmt/testdata/invalid_label_name.bad.yaml
@@ -0,0 +1,7 @@
+groups:
+- name: yolo
+  rules:
+  - record: hola
+    expr: 1
+    labels:
+      __name__: anything