From 0ee98bafad88a81b269e23873872f1eb0344da73 Mon Sep 17 00:00:00 2001
From: William Dumont <william.dumont@grafana.com>
Date: Fri, 13 Sep 2024 15:08:05 +0200
Subject: [PATCH] add cluster_name label to cluster metrics (#61)

---
 metrics.go | 33 +++++++++++++++++++++++++++++++--
 node.go    |  4 ++--
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/metrics.go b/metrics.go
index 34d3966..97a06e1 100644
--- a/metrics.go
+++ b/metrics.go
@@ -18,6 +18,8 @@ const (
 	eventNodeConflict     = "node_conflict"
 )
 
+const clusterNameLabel = "cluster_name"
+
 // metrics holds the set of metrics for a Node. Additional Collectors can be
 // registered by calling Add.
 type metrics struct {
@@ -33,38 +35,56 @@ type metrics struct {
 
 var _ prometheus.Collector = (*metrics)(nil)
 
-func newMetrics() *metrics {
+func newMetrics(clusterName string) *metrics {
 	var m metrics
 
 	m.gossipEventsTotal = prometheus.NewCounterVec(prometheus.CounterOpts{
 		Name: "cluster_node_gossip_received_events_total",
 		Help: "Total number of gossip messages handled by the node.",
+		ConstLabels: prometheus.Labels{
+			clusterNameLabel: clusterName,
+		},
 	}, []string{"event"})
 
 	m.nodePeers = prometheus.NewGaugeVec(prometheus.GaugeOpts{
 		Name: "cluster_node_peers",
 		Help: "Current number of healthy peers by state",
+		ConstLabels: prometheus.Labels{
+			clusterNameLabel: clusterName,
+		},
 	}, []string{"state"})
 
 	m.nodeUpdating = prometheus.NewGauge(prometheus.GaugeOpts{
 		Name: "cluster_node_updating",
 		Help: "1 if the node is currently processing a change to the cluster state.",
+		ConstLabels: prometheus.Labels{
+			clusterNameLabel: clusterName,
+		},
 	})
 
 	m.nodeUpdateDuration = prometheus.NewHistogram(prometheus.HistogramOpts{
 		Name:    "cluster_node_update_duration_seconds",
 		Help:    "Histogram of the latency it took to process a change to the cluster state.",
 		Buckets: prometheus.DefBuckets,
+		ConstLabels: prometheus.Labels{
+			clusterNameLabel: clusterName,
+		},
 	})
 
 	m.nodeObservers = prometheus.NewGauge(prometheus.GaugeOpts{
 		Name: "cluster_node_update_observers",
 		Help: "Number of internal observers waiting for changes to cluster state.",
+		ConstLabels: prometheus.Labels{
+			clusterNameLabel: clusterName,
+		},
 	})
 
 	m.nodeInfo = metricsutil.NewInfoCollector(metricsutil.InfoOpts{
 		Name: "cluster_node_info",
 		Help: "Info about the local node. Label values will change as the node changes state.",
+		ConstLabels: prometheus.Labels{
+			clusterNameLabel: clusterName,
+		},
 	}, "state")
 
 	m.Add(
@@ -79,12 +99,15 @@ func newMetrics() *metrics {
 	return &m
 }
 
-func newMemberlistCollector(ml *memberlist.Memberlist) prometheus.Collector {
+func newMemberlistCollector(ml *memberlist.Memberlist, clusterName string) prometheus.Collector {
 	var container metricsutil.Container
 
 	gossipProtoVersion := prometheus.NewGaugeFunc(prometheus.GaugeOpts{
 		Name: "cluster_node_gossip_proto_version",
 		Help: "Gossip protocol version used by nodes to maintain the cluster",
+		ConstLabels: prometheus.Labels{
+			clusterNameLabel: clusterName,
+		},
 	}, func() float64 {
 		// NOTE(rfratto): while this is static at the time of writing, the internal
 		// documentation for memberlist claims that ProtocolVersion may one day be
@@ -95,6 +118,9 @@ func newMemberlistCollector(ml *memberlist.Memberlist) prometheus.Collector {
 	gossipHealthScore := prometheus.NewGaugeFunc(prometheus.GaugeOpts{
 		Name: "cluster_node_gossip_health_score",
 		Help: "Health value of a node; lower values means healthier. 0 is the minimum.",
+		ConstLabels: prometheus.Labels{
+			clusterNameLabel: clusterName,
+		},
 	}, func() float64 {
 		return float64(ml.GetHealthScore())
 	})
@@ -102,6 +128,9 @@ func newMemberlistCollector(ml *memberlist.Memberlist) prometheus.Collector {
 	gossipPeers := prometheus.NewGaugeFunc(prometheus.GaugeOpts{
 		Name: "cluster_node_gossip_alive_peers",
 		Help: "How many alive gossip peers a node has, including the local node.",
+		ConstLabels: prometheus.Labels{
+			clusterNameLabel: clusterName,
+		},
 	}, func() float64 {
 		return float64(ml.NumMembers())
 	})
diff --git a/node.go b/node.go
index 721b35d..28b67fb 100644
--- a/node.go
+++ b/node.go
@@ -182,7 +182,7 @@ func NewNode(cli *http.Client, cfg Config) (*Node, error) {
 	n := &Node{
 		log: cfg.Log,
 		cfg: cfg,
-		m:   newMetrics(),
+		m:   newMetrics(mlc.Label),
 
 		notifyObserversQueue: queue.New(1),
 
@@ -209,7 +209,7 @@ func NewNode(cli *http.Client, cfg Config) (*Node, error) {
 
 	// Include some extra metrics.
 	n.m.Add(
-		newMemberlistCollector(ml),
+		newMemberlistCollector(ml, mlc.Label),
 		transportMetrics,
 		prometheus.NewGaugeFunc(prometheus.GaugeOpts{
 			Name: "cluster_node_lamport_time",