V0.40.0 rc.2 update refs (#6519)

* loki.write: fix duplicate metrics collector registration (#6511)

Fix an issue where re-creating a write client led to a duplicate
metrics collector registration panic.

Fixes #6510

(cherry picked from commit 34d9517)

* Update refs for v0.40.0-rc.2 (#6517)

- Update references in preparation for v0.40.0-rc.2 release

(cherry picked from commit 412a503)

---------

Co-authored-by: Robert Fratto <[email protected]>

CHANGELOG.md

@@ -8,7 +8,8 @@ changes that impact end-user behavior are listed; changes to documentation or
 internal API changes are not present.
 
 
-v0.40.0-rc.1 (2024-02-23)
+
+v0.40.0-rc.2 (2024-02-26)
 -------------------------
 
 ### Breaking changes
@@ -25,7 +26,7 @@ v0.40.0-rc.1 (2024-02-23)
 
 ### Features
 
-- Modules have been redesigned to split the import logic from the instantiation. 
+- Modules have been redesigned to split the import logic from the instantiation.
   You can now define custom components via the `declare` config block and import modules via `import.git`, `import.http`, `import.string`, `import.file`. (@wildum)
 
 - A new `discovery.process` component for discovering Linux OS processes on the current host. (@korniltsev)
@@ -38,7 +39,7 @@ v0.40.0-rc.1 (2024-02-23)
 - Expose track_timestamps_staleness on Prometheus scraping, to fix the issue where container metrics live for 5 minutes after the container disappears. (@ptodev)
 
 - Introduce the `remotecfg` service that enables loading configuration from a
-  remote endpoint. (@tpaschalis) 
+  remote endpoint. (@tpaschalis)
 
 - Add `otelcol.connector.host_info` component to gather usage metrics for cloud users. (@rlankfo, @jcreixell)
 
@@ -98,7 +99,7 @@ v0.40.0-rc.1 (2024-02-23)
 - Fix an issue where agent logs are emitted before the logging format
   is correctly determined. (@hainenber)
 
-- Fix divide-by-zero issue when sharding targets. (@hainenber) 
+- Fix divide-by-zero issue when sharding targets. (@hainenber)
 
 - Fix bug where custom headers were not actually being set in loki client. (@captncraig)
 
@@ -112,6 +113,8 @@ v0.40.0-rc.1 (2024-02-23)
 
 - Fix an issue where the configuration of the `http` and `remotecfg` blocks get ignored after loading a module. (@erikbaranowski)
 
+- Fix an issue where changing the configuration of `loki.write` would cause a panic. (@rfratto)
+
 ### Other changes
 
 - Removed support for Windows 2012 in line with Microsoft end of life. (@mattdurham)

component/common/loki/client/internal/metrics.go

@@ -1,6 +1,9 @@
 package internal
 
-import "github.com/prometheus/client_golang/prometheus"
+import (
+	"github.com/grafana/agent/pkg/util"
+	"github.com/prometheus/client_golang/prometheus"
+)
 
 type MarkerMetrics struct {
 	lastMarkedSegment *prometheus.GaugeVec
@@ -19,7 +22,7 @@ func NewMarkerMetrics(reg prometheus.Registerer) *MarkerMetrics {
 		),
 	}
 	if reg != nil {
-		reg.MustRegister(m.lastMarkedSegment)
+		m.lastMarkedSegment = util.MustRegisterOrGet(reg, m.lastMarkedSegment).(*prometheus.GaugeVec)
 	}
 	return m
 }

component/common/loki/client/manager_test.go

@@ -36,6 +36,28 @@ var (
 	metrics    = NewMetrics(prometheus.DefaultRegisterer)
 )
 
+// TestManager_NoDuplicateMetricsPanic ensures that creating two managers does
+// not lead to duplicate metrics registration.
+func TestManager_NoDuplicateMetricsPanic(t *testing.T) {
+	var (
+		host, _ = url.Parse("http://localhost:3100")
+
+		reg     = prometheus.NewRegistry()
+		metrics = NewMetrics(reg)
+	)
+
+	require.NotPanics(t, func() {
+		for i := 0; i < 2; i++ {
+			_, err := NewManager(metrics, log.NewLogfmtLogger(os.Stdout), testLimitsConfig, reg, wal.Config{
+				WatchConfig: wal.DefaultWatchConfig,
+			}, NilNotifier, Config{
+				URL: flagext.URLValue{URL: host},
+			})
+			require.NoError(t, err)
+		}
+	})
+}
+
 func TestManager_ErrorCreatingWhenNoClientConfigsProvided(t *testing.T) {
 	for _, walEnabled := range []bool{true, false} {
 		t.Run(fmt.Sprintf("wal-enabled = %t", walEnabled), func(t *testing.T) {

docs/sources/_index.md

@@ -9,7 +9,7 @@ title: Grafana Agent
 description: Grafana Agent is a flexible, performant, vendor-neutral, telemetry collector
 weight: 350
 cascade:
-  AGENT_RELEASE: v0.40.0-rc.1
+  AGENT_RELEASE: v0.40.0-rc.2
   OTEL_VERSION: v0.87.0
 ---
 

pkg/operator/defaults.go

@@ -2,7 +2,7 @@ package operator
 
 // Supported versions of the Grafana Agent.
 var (
-	DefaultAgentVersion   = "v0.40.0-rc.1"
+	DefaultAgentVersion   = "v0.40.0-rc.2"
 	DefaultAgentBaseImage = "grafana/agent"
 	DefaultAgentImage     = DefaultAgentBaseImage + ":" + DefaultAgentVersion
 )

tools/gen-versioned-files/agent-version.txt

@@ -1 +1 @@
-v0.40.0-rc.1
+v0.40.0-rc.2