From ce00b3862f81493f0a3fd3d63860d8967b6dfca7 Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@victoriametrics.com>
Date: Mon, 18 Jul 2022 17:15:02 +0300
Subject: [PATCH] lib/promscrape: reload all the scrape configs when the
 `global` section is changed inside `-promscrape.config`

See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2884
---
 docs/CHANGELOG.md        |  1 +
 lib/promscrape/config.go | 20 +++++++++++++++++++-
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 9c5965e0d..65b027354 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -18,6 +18,7 @@ The following tip changes can be tested by building VictoriaMetrics components f
 * BUGFIX: [VictoriaMetrics cluster](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html): fix potential panic in [multi-level cluster setup](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html#multi-level-cluster-setup) when top-level `vmselect` is configured with `-replicationFactor` bigger than 1. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2961).
 * BUGFIX: [vmagent](https://docs.victoriametrics.com/vmagent.html): properly handle custom `endpoint` value in [ec2_sd_configs](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#ec2_sd_config). It was ignored since [v1.77.0](https://docs.victoriametrics.com/CHANGELOG.html#v1770) because of a bug in the implementation of [this feature request](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1287).
 * BUGFIX: [vmagent](https://docs.victoriametrics.com/vmagent.html): set `up` metric to `0` for partial scrapes in [stream parsing mode](https://docs.victoriametrics.com/vmagent.html#stream-parsing-mode). Previously the `up` metric was set to `1` when at least a single metric has been scraped before the error. This aligns the behaviour of `vmselect` with Prometheus.
+* BUGFIX: [vmagent](https://docs.victoriametrics.com/vmagent.html): restart all the scrape jobs during [config reload](https://docs.victoriametrics.com/vmagent.html#configuration-update) after `global` section is changed inside `-promscrape.config`. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2884).
 
 
 ## [v1.79.1](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.79.1)
diff --git a/lib/promscrape/config.go b/lib/promscrape/config.go
index 9d9e64e70..b6b54d276 100644
--- a/lib/promscrape/config.go
+++ b/lib/promscrape/config.go
@@ -130,6 +130,10 @@ func (cfg *Config) mustRestart(prevCfg *Config) {
 		prevScrapeCfgByName[scPrev.JobName] = scPrev
 	}
 
+	// Restart all the scrape jobs on Global config change.
+	// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2884
+	needGlobalRestart := !areEqualGlobalConfigs(&cfg.Global, &prevCfg.Global)
+
 	// Loop over the the new jobs, start new ones and restart updated ones.
 	var started, stopped, restarted int
 	currentJobNames := make(map[string]struct{}, len(cfg.ScrapeConfigs))
@@ -142,7 +146,7 @@ func (cfg *Config) mustRestart(prevCfg *Config) {
 			started++
 			continue
 		}
-		if areEqualScrapeConfigs(scPrev, sc) {
+		if !needGlobalRestart && areEqualScrapeConfigs(scPrev, sc) {
 			// The scrape config didn't change, so no need to restart it.
 			// Use the reference to the previous job, so it could be stopped properly later.
 			cfg.ScrapeConfigs[i] = scPrev
@@ -165,6 +169,12 @@ func (cfg *Config) mustRestart(prevCfg *Config) {
 	logger.Infof("restarted service discovery routines in %.3f seconds, stopped=%d, started=%d, restarted=%d", time.Since(startTime).Seconds(), stopped, started, restarted)
 }
 
+func areEqualGlobalConfigs(a, b *GlobalConfig) bool {
+	sa := a.marshalJSON()
+	sb := b.marshalJSON()
+	return string(sa) == string(sb)
+}
+
 func areEqualScrapeConfigs(a, b *ScrapeConfig) bool {
 	sa := a.marshalJSON()
 	sb := b.marshalJSON()
@@ -183,6 +193,14 @@ func (sc *ScrapeConfig) marshalJSON() []byte {
 	return data
 }
 
+func (gc *GlobalConfig) marshalJSON() []byte {
+	data, err := json.Marshal(gc)
+	if err != nil {
+		logger.Panicf("BUG: cannot marshal GlobalConfig: %s", err)
+	}
+	return data
+}
+
 func (cfg *Config) mustStop() {
 	startTime := time.Now()
 	logger.Infof("stopping service discovery routines...")