From 2814b1490fcb67ea6334c11d4486e01503ca1561 Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@gmail.com>
Date: Mon, 13 Apr 2020 13:15:30 +0300
Subject: [PATCH] lib/promscrape: add `-promscrape.config.strictParse` flag for
 detecting errors in `-promscrape.config` file

---
 lib/promscrape/config.go | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/lib/promscrape/config.go b/lib/promscrape/config.go
index e8d2d4d6f..54969b160 100644
--- a/lib/promscrape/config.go
+++ b/lib/promscrape/config.go
@@ -1,6 +1,7 @@
 package promscrape
 
 import (
+	"flag"
 	"fmt"
 	"io/ioutil"
 	"net/url"
@@ -15,6 +16,11 @@ import (
 	"gopkg.in/yaml.v2"
 )
 
+var (
+	strictParse = flag.Bool("promscrape.config.strictParse", false, "Whether to allow only supported fields in '-promscrape.config'. "+
+		"This option may be used for errors detection in '-promscrape.config' file")
+)
+
 // Config represents essential parts from Prometheus config defined at https://prometheus.io/docs/prometheus/latest/configuration/configuration/
 type Config struct {
 	Global        GlobalConfig   `yaml:"global"`
@@ -101,7 +107,7 @@ func loadConfig(path string) (cfg *Config, err error) {
 }
 
 func (cfg *Config) parse(data []byte, path string) error {
-	if err := yaml.Unmarshal(data, cfg); err != nil {
+	if err := unmarshalMaybeStrict(data, cfg); err != nil {
 		return fmt.Errorf("cannot unmarshal data: %s", err)
 	}
 	absPath, err := filepath.Abs(path)
@@ -120,6 +126,16 @@ func (cfg *Config) parse(data []byte, path string) error {
 	return nil
 }
 
+func unmarshalMaybeStrict(data []byte, dst interface{}) error {
+	var err error
+	if *strictParse {
+		err = yaml.UnmarshalStrict(data, dst)
+	} else {
+		err = yaml.Unmarshal(data, dst)
+	}
+	return err
+}
+
 func (cfg *Config) fileSDConfigsCount() int {
 	n := 0
 	for i := range cfg.ScrapeConfigs {