From c755fa99357b9e81e4a2979365865c63fe020710 Mon Sep 17 00:00:00 2001
From: David Ashpole <dashpole@google.com>
Date: Fri, 5 Apr 2024 16:00:52 +0000
Subject: [PATCH] support unregistering scrape manager metrics

Signed-off-by: David Ashpole <dashpole@google.com>
---
 scrape/manager.go      |  5 +++++
 scrape/manager_test.go | 13 +++++++++++++
 scrape/metrics.go      | 29 ++++++++++++++++++++++++++++-
 3 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/scrape/manager.go b/scrape/manager.go
index 3ad315a50..e805fd43a 100644
--- a/scrape/manager.go
+++ b/scrape/manager.go
@@ -129,6 +129,11 @@ func (m *Manager) Run(tsets <-chan map[string][]*targetgroup.Group) error {
 	}
 }
 
+// UnregisterMetrics unregisters manager metrics.
+func (m *Manager) UnregisterMetrics() {
+	m.metrics.Unregister()
+}
+
 func (m *Manager) reloader() {
 	reloadIntervalDuration := m.opts.DiscoveryReloadInterval
 	if reloadIntervalDuration < model.Duration(5*time.Second) {
diff --git a/scrape/manager_test.go b/scrape/manager_test.go
index f90fd0ce6..51af45f8c 100644
--- a/scrape/manager_test.go
+++ b/scrape/manager_test.go
@@ -857,3 +857,16 @@ func getResultFloats(app *collectResultAppender, expectedMetricName string) (res
 	}
 	return result
 }
+
+func TestUnregisterMetrics(t *testing.T) {
+	reg := prometheus.NewRegistry()
+	// Check that all metrics can be unregistered, allowing a second manager to be created.
+	for i := 0; i < 2; i++ {
+		opts := Options{}
+		manager, err := NewManager(&opts, nil, nil, reg)
+		require.NotNil(t, manager)
+		require.NoError(t, err)
+		// Unregister all metrics.
+		manager.UnregisterMetrics()
+	}
+}
diff --git a/scrape/metrics.go b/scrape/metrics.go
index 7082bc743..b67d0686b 100644
--- a/scrape/metrics.go
+++ b/scrape/metrics.go
@@ -20,6 +20,7 @@ import (
 )
 
 type scrapeMetrics struct {
+	reg prometheus.Registerer
 	// Used by Manager.
 	targetMetadataCache     *MetadataMetricsCollector
 	targetScrapePools       prometheus.Counter
@@ -54,7 +55,7 @@ type scrapeMetrics struct {
 }
 
 func newScrapeMetrics(reg prometheus.Registerer) (*scrapeMetrics, error) {
-	sm := &scrapeMetrics{}
+	sm := &scrapeMetrics{reg: reg}
 
 	// Manager metrics.
 	sm.targetMetadataCache = &MetadataMetricsCollector{
@@ -260,6 +261,32 @@ func (sm *scrapeMetrics) setTargetMetadataCacheGatherer(gatherer TargetsGatherer
 	sm.targetMetadataCache.TargetsGatherer = gatherer
 }
 
+// Unregister unregisters all metrics.
+func (sm *scrapeMetrics) Unregister() {
+	sm.reg.Unregister(sm.targetMetadataCache)
+	sm.reg.Unregister(sm.targetScrapePools)
+	sm.reg.Unregister(sm.targetScrapePoolsFailed)
+	sm.reg.Unregister(sm.targetReloadIntervalLength)
+	sm.reg.Unregister(sm.targetScrapePoolReloads)
+	sm.reg.Unregister(sm.targetScrapePoolReloadsFailed)
+	sm.reg.Unregister(sm.targetSyncIntervalLength)
+	sm.reg.Unregister(sm.targetScrapePoolSyncsCounter)
+	sm.reg.Unregister(sm.targetScrapePoolExceededTargetLimit)
+	sm.reg.Unregister(sm.targetScrapePoolTargetLimit)
+	sm.reg.Unregister(sm.targetScrapePoolTargetsAdded)
+	sm.reg.Unregister(sm.targetSyncFailed)
+	sm.reg.Unregister(sm.targetScrapeExceededBodySizeLimit)
+	sm.reg.Unregister(sm.targetScrapeCacheFlushForced)
+	sm.reg.Unregister(sm.targetIntervalLength)
+	sm.reg.Unregister(sm.targetScrapeSampleLimit)
+	sm.reg.Unregister(sm.targetScrapeSampleDuplicate)
+	sm.reg.Unregister(sm.targetScrapeSampleOutOfOrder)
+	sm.reg.Unregister(sm.targetScrapeSampleOutOfBounds)
+	sm.reg.Unregister(sm.targetScrapeExemplarOutOfOrder)
+	sm.reg.Unregister(sm.targetScrapePoolExceededLabelLimits)
+	sm.reg.Unregister(sm.targetScrapeNativeHistogramBucketLimit)
+}
+
 type TargetsGatherer interface {
 	TargetsActive() map[string][]*Target
 }