[#80] Add type to metrics description

Signed-off-by: Denis Kirillov <d.kirillov@yadro.com>

go.mod

@@ -15,6 +15,7 @@ require (
 	github.com/nspcc-dev/neo-go v0.101.0
 	github.com/panjf2000/ants/v2 v2.5.0
 	github.com/prometheus/client_golang v1.13.0
+	github.com/prometheus/client_model v0.2.0
 	github.com/spf13/pflag v1.0.5
 	github.com/spf13/viper v1.15.0
 	github.com/stretchr/testify v1.8.1
@@ -31,6 +32,7 @@ require (
 	git.frostfs.info/TrueCloudLab/rfc6979 v0.4.0 // indirect
 	git.frostfs.info/TrueCloudLab/tzhash v1.8.0 // indirect
 	github.com/antlr/antlr4/runtime/Go/antlr/v4 v4.0.0-20221202181307-76fa05c21b12 // indirect
+	github.com/benbjohnson/clock v1.1.0 // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cespare/xxhash/v2 v2.1.2 // indirect
 	github.com/cpuguy83/go-md2man/v2 v2.0.2 // indirect
@@ -56,7 +58,6 @@ require (
 	github.com/nspcc-dev/rfc6979 v0.2.0 // indirect
 	github.com/pelletier/go-toml/v2 v2.0.6 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	github.com/prometheus/client_model v0.2.0 // indirect
 	github.com/prometheus/common v0.37.0 // indirect
 	github.com/prometheus/procfs v0.8.0 // indirect
 	github.com/russross/blackfriday/v2 v2.1.0 // indirect

metrics/app.go

@@ -4,6 +4,7 @@ import (
 	"net/http"
 	"sync"
 
+	dto "github.com/prometheus/client_model/go"
 	"go.uber.org/zap"
 )
 
@@ -78,3 +79,7 @@ func (m *AppMetrics) Statistic() *APIStatMetrics {
 
 	return m.gate.Stats
 }
+
+func (m *AppMetrics) Gather() ([]*dto.MetricFamily, error) {
+	return m.gate.Gather()
+}

metrics/billing.go

@@ -203,11 +203,15 @@ func newBillingMetrics() *billingMetrics {
 	}
 }
 
-func (b *billingMetrics) register() {
+func (b *billingMetrics) Gatherer() prometheus.Gatherer {
+	return b.registry
+}
+
+func (b *billingMetrics) Register() {
 	b.registry.MustRegister(b)
 }
 
-func (b *billingMetrics) unregister() {
+func (b *billingMetrics) Unregister() {
 	b.registry.Unregister(b)
 }
 

metrics/desc.go

@@ -4,17 +4,20 @@ import (
 	"encoding/json"
 
 	"github.com/prometheus/client_golang/prometheus"
+	dto "github.com/prometheus/client_model/go"
 )
 
 var appMetricsDesc = map[string]map[string]Description{
 	poolSubsystem: {
 		overallErrorsMetric: Description{
+			Type:      dto.MetricType_GAUGE,
 			Namespace: namespace,
 			Subsystem: poolSubsystem,
 			Name:      overallErrorsMetric,
 			Help:      "Total number of errors in pool",
 		},
 		overallNodeErrorsMetric: Description{
+			Type:           dto.MetricType_GAUGE,
 			Namespace:      namespace,
 			Subsystem:      poolSubsystem,
 			Name:           overallNodeErrorsMetric,
@@ -22,6 +25,7 @@ var appMetricsDesc = map[string]map[string]Description{
 			VariableLabels: []string{"node"},
 		},
 		overallNodeRequestsMetric: Description{
+			Type:           dto.MetricType_GAUGE,
 			Namespace:      namespace,
 			Subsystem:      poolSubsystem,
 			Name:           overallNodeRequestsMetric,
@@ -29,6 +33,7 @@ var appMetricsDesc = map[string]map[string]Description{
 			VariableLabels: []string{"node"},
 		},
 		currentErrorMetric: Description{
+			Type:           dto.MetricType_GAUGE,
 			Namespace:      namespace,
 			Subsystem:      poolSubsystem,
 			Name:           currentErrorMetric,
@@ -36,6 +41,7 @@ var appMetricsDesc = map[string]map[string]Description{
 			VariableLabels: []string{"node"},
 		},
 		avgRequestDurationMetric: Description{
+			Type:           dto.MetricType_GAUGE,
 			Namespace:      namespace,
 			Subsystem:      poolSubsystem,
 			Name:           avgRequestDurationMetric,
@@ -45,6 +51,7 @@ var appMetricsDesc = map[string]map[string]Description{
 	},
 	billingSubsystem: {
 		userRequestsMetric: Description{
+			Type:           dto.MetricType_GAUGE,
 			Namespace:      namespace,
 			Subsystem:      billingSubsystem,
 			Name:           userRequestsMetric,
@@ -52,6 +59,7 @@ var appMetricsDesc = map[string]map[string]Description{
 			VariableLabels: []string{"user", "bucket", "cid", "operation"},
 		},
 		userTrafficMetric: Description{
+			Type:           dto.MetricType_GAUGE,
 			Namespace:      namespace,
 			Subsystem:      billingSubsystem,
 			Name:           userTrafficMetric,
@@ -61,12 +69,14 @@ var appMetricsDesc = map[string]map[string]Description{
 	},
 	stateSubsystem: {
 		healthMetric: Description{
+			Type:      dto.MetricType_GAUGE,
 			Namespace: namespace,
 			Subsystem: stateSubsystem,
 			Name:      healthMetric,
 			Help:      "Current S3 gateway state",
 		},
 		versionInfoMetric: Description{
+			Type:           dto.MetricType_GAUGE,
 			Namespace:      namespace,
 			Subsystem:      stateSubsystem,
 			Name:           versionInfoMetric,
@@ -76,6 +86,7 @@ var appMetricsDesc = map[string]map[string]Description{
 	},
 	statisticSubsystem: {
 		requestsSecondsMetric: Description{
+			Type:           dto.MetricType_HISTOGRAM,
 			Namespace:      namespace,
 			Subsystem:      statisticSubsystem,
 			Name:           requestsSecondsMetric,
@@ -83,6 +94,7 @@ var appMetricsDesc = map[string]map[string]Description{
 			VariableLabels: []string{"api"},
 		},
 		requestsCurrentMetric: Description{
+			Type:           dto.MetricType_GAUGE,
 			Namespace:      namespace,
 			Subsystem:      statisticSubsystem,
 			Name:           requestsCurrentMetric,
@@ -90,6 +102,7 @@ var appMetricsDesc = map[string]map[string]Description{
 			VariableLabels: []string{"api"},
 		},
 		requestsTotalMetric: Description{
+			Type:           dto.MetricType_GAUGE,
 			Namespace:      namespace,
 			Subsystem:      statisticSubsystem,
 			Name:           requestsTotalMetric,
@@ -97,6 +110,7 @@ var appMetricsDesc = map[string]map[string]Description{
 			VariableLabels: []string{"api"},
 		},
 		errorsTotalMetric: Description{
+			Type:           dto.MetricType_GAUGE,
 			Namespace:      namespace,
 			Subsystem:      statisticSubsystem,
 			Name:           errorsTotalMetric,
@@ -104,12 +118,14 @@ var appMetricsDesc = map[string]map[string]Description{
 			VariableLabels: []string{"api"},
 		},
 		txBytesTotalMetric: Description{
+			Type:      dto.MetricType_GAUGE,
 			Namespace: namespace,
 			Subsystem: statisticSubsystem,
 			Name:      txBytesTotalMetric,
 			Help:      "Total number of bytes sent by current FrostFS S3 Gate instance",
 		},
 		rxBytesTotalMetric: Description{
+			Type:      dto.MetricType_GAUGE,
 			Namespace: namespace,
 			Subsystem: statisticSubsystem,
 			Name:      rxBytesTotalMetric,
@@ -119,6 +135,7 @@ var appMetricsDesc = map[string]map[string]Description{
 }
 
 type Description struct {
+	Type           dto.MetricType
 	Namespace      string
 	Subsystem      string
 	Name           string
@@ -134,11 +151,13 @@ type KeyValue struct {
 
 func (d *Description) MarshalJSON() ([]byte, error) {
 	return json.Marshal(&struct {
+		Type           string     `json:"type"`
 		FQName         string     `json:"name"`
 		Help           string     `json:"help"`
 		ConstantLabels []KeyValue `json:"constant_labels"`
 		VariableLabels []string   `json:"variable_labels"`
 	}{
+		Type:           d.Type.String(),
 		FQName:         d.BuildFQName(),
 		Help:           d.Help,
 		ConstantLabels: d.ConstantLabels,
@@ -188,15 +207,39 @@ func newDesc(description Description) *prometheus.Desc {
 		description.ConstLabelsMap())
 }
 
-func newGauge(description Description) prometheus.Gauge {
+func mustNewGauge(description Description) prometheus.Gauge {
+	if description.Type != dto.MetricType_GAUGE {
+		panic("invalid metric type")
+	}
 	return prometheus.NewGauge(
 		prometheus.GaugeOpts(newOpts(description)),
 	)
 }
 
-func newGaugeVec(description Description) *prometheus.GaugeVec {
+func mustNewGaugeVec(description Description) *prometheus.GaugeVec {
+	if description.Type != dto.MetricType_GAUGE {
+		panic("invalid metric type")
+	}
 	return prometheus.NewGaugeVec(
 		prometheus.GaugeOpts(newOpts(description)),
 		description.VariableLabels,
 	)
 }
+
+func mustNewHistogramVec(description Description, buckets []float64) *prometheus.HistogramVec {
+	if description.Type != dto.MetricType_HISTOGRAM {
+		panic("invalid metric type")
+	}
+
+	return prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Namespace:   description.Namespace,
+			Subsystem:   description.Subsystem,
+			Name:        description.Name,
+			Help:        description.Name,
+			ConstLabels: description.ConstLabelsMap(),
+			Buckets:     buckets,
+		},
+		description.VariableLabels,
+	)
+}

metrics/desc_test.go

@@ -8,12 +8,24 @@ import (
 	"os"
 	"testing"
 
+	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/pool"
 	"github.com/stretchr/testify/require"
+	"go.uber.org/zap/zaptest"
 )
 
+type mock struct {
+}
+
+func (m mock) Statistic() pool.Statistic {
+	return pool.Statistic{}
+}
+
 var metricsPath = flag.String("out", "", "File to export s3 gateway metrics to.")
 
 func TestDescribeAll(t *testing.T) {
+	// to check correct metrics type mapping
+	_ = NewAppMetrics(zaptest.NewLogger(t), mock{}, true)
+
 	flag.Parse()
 
 	require.NotEmpty(t, metricsPath, "flag 'out' must be provided to dump metrics description")

metrics/gate.go

@@ -6,6 +6,7 @@ import (
 	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/pool"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
+	dto "github.com/prometheus/client_model/go"
 )
 
 const namespace = "frostfs_s3_gw"
@@ -15,43 +16,51 @@ type StatisticScraper interface {
 }
 
 type GateMetrics struct {
+	registry *prometheus.Registry
 	State    *StateMetrics
-	Pool    poolMetricsCollector
+	Pool     *poolMetricsCollector
 	Billing  *billingMetrics
 	Stats    *APIStatMetrics
 }
 
 func NewGateMetrics(scraper StatisticScraper) *GateMetrics {
+	registry := prometheus.NewRegistry()
+
 	stateMetric := newStateMetrics()
-	stateMetric.register()
+	registry.MustRegister(stateMetric)
 
 	poolMetric := newPoolMetricsCollector(scraper)
-	poolMetric.register()
+	registry.MustRegister(poolMetric)
 
 	billingMetric := newBillingMetrics()
-	billingMetric.register()
+	billingMetric.Register()
 
 	statsMetric := newAPIStatMetrics()
-	statsMetric.register()
+	registry.MustRegister(statsMetric)
 
 	return &GateMetrics{
+		registry: registry,
 		State:    stateMetric,
-		Pool:    *poolMetric,
+		Pool:     poolMetric,
 		Billing:  billingMetric,
 		Stats:    statsMetric,
 	}
 }
 
 func (g *GateMetrics) Unregister() {
-	g.State.unregister()
+	g.registry.Unregister(g.State)
-	prometheus.Unregister(&g.Pool)
+	g.registry.Unregister(g.Pool)
-	g.Billing.unregister()
+	g.Billing.Unregister()
-	g.Stats.unregister()
+	g.registry.Unregister(g.Stats)
 }
 
 func (g *GateMetrics) Handler() http.Handler {
 	handler := http.NewServeMux()
 	handler.Handle("/", promhttp.Handler())
-	handler.Handle("/metrics/billing", promhttp.HandlerFor(g.Billing.registry, promhttp.HandlerOpts{}))
+	handler.Handle("/metrics/billing", promhttp.HandlerFor(g.Billing.Gatherer(), promhttp.HandlerOpts{}))
 	return handler
 }
+
+func (g *GateMetrics) Gather() ([]*dto.MetricFamily, error) {
+	return prometheus.Gatherers([]prometheus.Gatherer{g.Billing.Gatherer()}).Gather()
+}

metrics/pool.go

@@ -47,11 +47,11 @@ type poolMetricsCollector struct {
 func newPoolMetricsCollector(scraper StatisticScraper) *poolMetricsCollector {
 	return &poolMetricsCollector{
 		poolStatScraper:     scraper,
-		overallErrors:       newGauge(appMetricsDesc[poolSubsystem][overallErrorsMetric]),
+		overallErrors:       mustNewGauge(appMetricsDesc[poolSubsystem][overallErrorsMetric]),
-		overallNodeErrors:   newGaugeVec(appMetricsDesc[poolSubsystem][overallNodeErrorsMetric]),
+		overallNodeErrors:   mustNewGaugeVec(appMetricsDesc[poolSubsystem][overallNodeErrorsMetric]),
-		overallNodeRequests: newGaugeVec(appMetricsDesc[poolSubsystem][overallNodeRequestsMetric]),
+		overallNodeRequests: mustNewGaugeVec(appMetricsDesc[poolSubsystem][overallNodeRequestsMetric]),
-		currentErrors:       newGaugeVec(appMetricsDesc[poolSubsystem][currentErrorMetric]),
+		currentErrors:       mustNewGaugeVec(appMetricsDesc[poolSubsystem][currentErrorMetric]),
-		requestDuration:     newGaugeVec(appMetricsDesc[poolSubsystem][avgRequestDurationMetric]),
+		requestDuration:     mustNewGaugeVec(appMetricsDesc[poolSubsystem][avgRequestDurationMetric]),
 	}
 }
 
@@ -72,10 +72,6 @@ func (m *poolMetricsCollector) Describe(descs chan<- *prometheus.Desc) {
 	m.requestDuration.Describe(descs)
 }
 
-func (m *poolMetricsCollector) register() {
-	prometheus.MustRegister(m)
-}
-
 func (m *poolMetricsCollector) updateStatistic() {
 	stat := m.poolStatScraper.Statistic()
 

metrics/state.go

@@ -28,25 +28,11 @@ type StateMetrics struct {
 
 func newStateMetrics() *StateMetrics {
 	return &StateMetrics{
-		healthCheck: newGauge(appMetricsDesc[stateSubsystem][healthMetric]),
+		healthCheck: mustNewGauge(appMetricsDesc[stateSubsystem][healthMetric]),
-		versionInfo: newGaugeVec(appMetricsDesc[stateSubsystem][versionInfoMetric]),
+		versionInfo: mustNewGaugeVec(appMetricsDesc[stateSubsystem][versionInfoMetric]),
 	}
 }
 
-func (m *StateMetrics) register() {
-	if m == nil {
-		return
-	}
-	prometheus.MustRegister(m.healthCheck)
-}
-
-func (m *StateMetrics) unregister() {
-	if m == nil {
-		return
-	}
-	prometheus.Unregister(m.healthCheck)
-}
-
 func (m *StateMetrics) SetHealth(s HealthStatus) {
 	if m == nil {
 		return
@@ -60,3 +46,21 @@ func (m *StateMetrics) SetVersion(ver string) {
 	}
 	m.versionInfo.WithLabelValues(ver).Set(1)
 }
+
+func (m *StateMetrics) Describe(desc chan<- *prometheus.Desc) {
+	if m == nil {
+		return
+	}
+
+	m.healthCheck.Describe(desc)
+	m.versionInfo.Describe(desc)
+}
+
+func (m *StateMetrics) Collect(ch chan<- prometheus.Metric) {
+	if m == nil {
+		return
+	}
+
+	m.healthCheck.Collect(ch)
+	m.versionInfo.Collect(ch)
+}

metrics/stats.go

@@ -56,36 +56,11 @@ func newAPIStatMetrics() *APIStatMetrics {
 
 	return &APIStatMetrics{
 		stats: newHTTPStats(),
-		httpRequestsDuration: prometheus.NewHistogramVec(
+		httpRequestsDuration: mustNewHistogramVec(histogramDesc,
-			prometheus.HistogramOpts{
+			[]float64{.05, .1, .25, .5, 1, 2.5, 5, 10}),
-				Namespace:   histogramDesc.Namespace,
-				Subsystem:   histogramDesc.Subsystem,
-				Name:        histogramDesc.Name,
-				Help:        histogramDesc.Name,
-				ConstLabels: histogramDesc.ConstLabelsMap(),
-				Buckets:     []float64{.05, .1, .25, .5, 1, 2.5, 5, 10},
-			},
-			histogramDesc.VariableLabels,
-		),
 	}
 }
 
-func (a *APIStatMetrics) register() {
-	if a == nil {
-		return
-	}
-	prometheus.MustRegister(a.stats)
-	prometheus.MustRegister(a.httpRequestsDuration)
-}
-
-func (a *APIStatMetrics) unregister() {
-	if a == nil {
-		return
-	}
-	prometheus.Unregister(a.stats)
-	prometheus.Unregister(a.httpRequestsDuration)
-}
-
 func (a *APIStatMetrics) CurrentS3RequestsInc(api string) {
 	if a == nil {
 		return