[#164] metrics: Fill local registry explicitly

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

cmd/frostfs-node/metrics.go

@@ -2,7 +2,7 @@ package main
 
 import (
 	metricsconfig "git.frostfs.info/TrueCloudLab/frostfs-node/cmd/frostfs-node/config/metrics"
-	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/metrics"
 )
 
 func metricsComponent(c *cfg) (*httpComponent, bool) {
@@ -12,7 +12,7 @@ func metricsComponent(c *cfg) (*httpComponent, bool) {
 		c.dynamicConfiguration.metrics = new(httpComponent)
 		c.dynamicConfiguration.metrics.cfg = c
 		c.dynamicConfiguration.metrics.name = "metrics"
-		c.dynamicConfiguration.metrics.handler = promhttp.Handler()
+		c.dynamicConfiguration.metrics.handler = metrics.Handler()
 		updated = true
 	}
 

pkg/metrics/engine.go

@@ -72,19 +72,19 @@ func newEngineGaugeVector(name, help string, labels []string) *prometheus.GaugeV
 }
 
 func (m engineMetrics) register() {
-	prometheus.MustRegister(m.listContainersDuration)
-	prometheus.MustRegister(m.estimateContainerSizeDuration)
-	prometheus.MustRegister(m.deleteDuration)
-	prometheus.MustRegister(m.existsDuration)
-	prometheus.MustRegister(m.getDuration)
-	prometheus.MustRegister(m.headDuration)
-	prometheus.MustRegister(m.inhumeDuration)
-	prometheus.MustRegister(m.putDuration)
-	prometheus.MustRegister(m.rangeDuration)
-	prometheus.MustRegister(m.searchDuration)
-	prometheus.MustRegister(m.listObjectsDuration)
-	prometheus.MustRegister(m.containerSize)
-	prometheus.MustRegister(m.payloadSize)
+	mustRegister(m.listContainersDuration)
+	mustRegister(m.estimateContainerSizeDuration)
+	mustRegister(m.deleteDuration)
+	mustRegister(m.existsDuration)
+	mustRegister(m.getDuration)
+	mustRegister(m.headDuration)
+	mustRegister(m.inhumeDuration)
+	mustRegister(m.putDuration)
+	mustRegister(m.rangeDuration)
+	mustRegister(m.searchDuration)
+	mustRegister(m.listObjectsDuration)
+	mustRegister(m.containerSize)
+	mustRegister(m.payloadSize)
 }
 
 func (m engineMetrics) AddListContainersDuration(d time.Duration) {

pkg/metrics/innerring.go

@@ -27,8 +27,8 @@ func NewInnerRingMetrics() InnerRingServiceMetrics {
 		})
 	)
 
-	prometheus.MustRegister(epoch)
-	prometheus.MustRegister(health)
+	mustRegister(epoch)
+	mustRegister(health)
 
 	return InnerRingServiceMetrics{
 		epoch:  epoch,

pkg/metrics/metrics.go

@@ -27,7 +27,7 @@ func NewNodeMetrics() *NodeMetrics {
 		Name:      "epoch",
 		Help:      "Current epoch as seen by inner-ring node.",
 	})
-	prometheus.MustRegister(epoch)
+	mustRegister(epoch)
 
 	return &NodeMetrics{
 		objectServiceMetrics: objectService,

pkg/metrics/object.go

@@ -65,8 +65,8 @@ func newObjectMethodCallCounter(name string) methodCount {
 }
 
 func (m methodCount) mustRegister() {
-	prometheus.MustRegister(m.success)
-	prometheus.MustRegister(m.total)
+	mustRegister(m.success)
+	mustRegister(m.total)
 }
 
 func (m methodCount) Inc(success bool) {
@@ -135,19 +135,19 @@ func (m objectServiceMetrics) register() {
 	m.rangeCounter.mustRegister()
 	m.rangeHashCounter.mustRegister()
 
-	prometheus.MustRegister(m.getDuration)
-	prometheus.MustRegister(m.putDuration)
-	prometheus.MustRegister(m.headDuration)
-	prometheus.MustRegister(m.searchDuration)
-	prometheus.MustRegister(m.deleteDuration)
-	prometheus.MustRegister(m.rangeDuration)
-	prometheus.MustRegister(m.rangeHashDuration)
+	mustRegister(m.getDuration)
+	mustRegister(m.putDuration)
+	mustRegister(m.headDuration)
+	mustRegister(m.searchDuration)
+	mustRegister(m.deleteDuration)
+	mustRegister(m.rangeDuration)
+	mustRegister(m.rangeHashDuration)
 
-	prometheus.MustRegister(m.putPayload)
-	prometheus.MustRegister(m.getPayload)
+	mustRegister(m.putPayload)
+	mustRegister(m.getPayload)
 
-	prometheus.MustRegister(m.shardMetrics)
-	prometheus.MustRegister(m.shardsReadonly)
+	mustRegister(m.shardMetrics)
+	mustRegister(m.shardsReadonly)
 }
 
 func (m objectServiceMetrics) IncGetReqCounter(success bool) {

pkg/metrics/registry.go

@@ -0,0 +1,40 @@
+package metrics
+
+import (
+	"net/http"
+	"sync"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/collectors"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+// Handler returns an http.Handler for the local registry.
+func Handler() http.Handler {
+	promhttp.Handler()
+	return promhttp.InstrumentMetricHandler(
+		registry,
+		promhttp.HandlerFor(registry, promhttp.HandlerOpts{}))
+}
+
+var (
+	registry = prometheus.NewRegistry()
+	// registeredCollectorsMtx protects collectors slice.
+	// It should not be acessed concurrently, but we can easily forget this in future, thus this mutex.
+	registeredCollectorsMtx sync.Mutex
+	registeredCollectors    []prometheus.Collector
+)
+
+func init() {
+	mustRegister(collectors.NewProcessCollector(collectors.ProcessCollectorOpts{}))
+	mustRegister(collectors.NewGoCollector())
+}
+
+func mustRegister(cs ...prometheus.Collector) {
+	for i := range cs {
+		registry.MustRegister(cs[i])
+	}
+	registeredCollectorsMtx.Lock()
+	registeredCollectors = append(registeredCollectors, cs...)
+	registeredCollectorsMtx.Unlock()
+}

pkg/metrics/state.go

@@ -20,7 +20,7 @@ func newStateMetrics() stateMetrics {
 }
 
 func (m stateMetrics) register() {
-	prometheus.MustRegister(m.healthCheck)
+	mustRegister(m.healthCheck)
 }
 
 func (m stateMetrics) SetHealth(s int32) {