From 3f52e59efe7d05880ff690d0a0e311e1a2797cfa Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@gmail.com>
Date: Wed, 25 Nov 2020 22:59:13 +0200
Subject: [PATCH] app/{vmagent,victoria-metrics}: add `-dryRun` option and make
 more clear handling for `-promscrape.config.dryRun`

---
 app/vmagent/main.go      |  9 ++++++++-
 docs/CHANGELOG.md        |  1 +
 lib/promscrape/config.go | 13 +++++--------
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/app/vmagent/main.go b/app/vmagent/main.go
index bcff08e83f..df0fc9ee25 100644
--- a/app/vmagent/main.go
+++ b/app/vmagent/main.go
@@ -69,12 +69,19 @@ func main() {
 	logger.Init()
 	cgroup.UpdateGOMAXPROCSToCPUQuota()
 
+	if promscrape.IsDryRun() {
+		if err := promscrape.CheckConfig(); err != nil {
+			logger.Fatalf("error when checking -promscrape.config: %s", err)
+		}
+		logger.Infof("-promscrape.config is ok; exitting with 0 status code")
+		return
+	}
 	if *dryRun {
 		if err := remotewrite.CheckRelabelConfigs(); err != nil {
 			logger.Fatalf("error when checking relabel configs: %s", err)
 		}
 		if err := promscrape.CheckConfig(); err != nil {
-			logger.Fatalf("error when checking Prometheus config: %s", err)
+			logger.Fatalf("error when checking -promscrape.config: %s", err)
 		}
 		logger.Infof("all the configs are ok; exitting with 0 status code")
 		return
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index abbb0c8b51..02fb8c0707 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -20,6 +20,7 @@ See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/851
   Slow query logging is controlled with `-search.logSlowQueryDuration` command-line flag.
 * FEATURE: add `/tags/delSeries` handler from Graphite Tags API. See https://victoriametrics.github.io/#graphite-tags-api-usage
 * FEATURE: log metric name plus all its labels when the metric timestamp is out of the configured retention. This should simplify detecting the source of metrics with unexpected timestamps.
+* FEATURE: add `-dryRun` command-line flag to single-node VictoriaMetrics in order to check config file pointed by `-promscrape.config`.
 
 * BUGFIX: properly parse Prometheus metrics with [exemplars](https://github.com/OpenObservability/OpenMetrics/blob/master/OpenMetrics.md#exemplars-1) such as `foo 123 # {bar="baz"} 1`.
 * BUGFIX: properly parse "infinity" values in [OpenMetrics format](https://github.com/OpenObservability/OpenMetrics/blob/master/OpenMetrics.md#abnf).
diff --git a/lib/promscrape/config.go b/lib/promscrape/config.go
index 1a8b1fdd2c..007ec267c1 100644
--- a/lib/promscrape/config.go
+++ b/lib/promscrape/config.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"io/ioutil"
 	"net/url"
-	"os"
 	"path/filepath"
 	"strings"
 	"sync/atomic"
@@ -134,16 +133,14 @@ func loadConfig(path string) (cfg *Config, data []byte, err error) {
 	if err := cfgObj.parse(data, path); err != nil {
 		return nil, nil, fmt.Errorf("cannot parse Prometheus config from %q: %w", path, err)
 	}
-	if *dryRun {
-		// This is a dirty hack for checking Prometheus config only.
-		// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/362
-		// and https://github.com/VictoriaMetrics/VictoriaMetrics/issues/508 for details.
-		logger.Infof("Success: the config at %q has no errors; exitting with 0 status code", path)
-		os.Exit(0)
-	}
 	return &cfgObj, data, nil
 }
 
+// IsDryRun returns true if -promscrape.config.dryRun command-line flag is set
+func IsDryRun() bool {
+	return *dryRun
+}
+
 func (cfg *Config) parse(data []byte, path string) error {
 	if err := unmarshalMaybeStrict(data, cfg); err != nil {
 		return fmt.Errorf("cannot unmarshal data: %w", err)