[#29] Add type to metrics description

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

go.mod

@@ -8,6 +8,7 @@ require (
 	github.com/fasthttp/router v1.4.1
 	github.com/nspcc-dev/neo-go v0.101.0
 	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
@@ -68,7 +69,6 @@ require (
 	github.com/pelletier/go-toml/v2 v2.0.6 // indirect
 	github.com/pkg/errors v0.9.1 // 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/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,
@@ -45,12 +51,14 @@ var appMetricsDesc = map[string]map[string]Description{
 	},
 	stateSubsystem: {
 		healthMetric: Description{
+			Type:      dto.MetricType_GAUGE,
 			Namespace: namespace,
 			Subsystem: stateSubsystem,
 			Name:      healthMetric,
 			Help:      "Current HTTP gateway state",
 		},
 		versionInfoMetric: Description{
+			Type:           dto.MetricType_GAUGE,
 			Namespace:      namespace,
 			Subsystem:      stateSubsystem,
 			Name:           versionInfoMetric,
@@ -61,6 +69,7 @@ var appMetricsDesc = map[string]map[string]Description{
 }
 
 type Description struct {
+	Type           dto.MetricType
 	Namespace      string
 	Subsystem      string
 	Name           string
@@ -76,11 +85,13 @@ 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,
@@ -122,13 +133,19 @@ func newOpts(description Description) prometheus.Opts {
 	}
 }
 
-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,

metrics/desc_test.go

@@ -8,17 +8,28 @@ import (
 	"os"
 	"testing"
 
+	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/pool"
 	"github.com/stretchr/testify/require"
 )
 
+type mock struct{}
+
+func (m mock) Statistic() pool.Statistic {
+	return pool.Statistic{}
+}
+
 var metricsPath = flag.String("out", "", "File to export http gateway metrics to.")
 
 func TestDescribeAll(t *testing.T) {
+	// to check correct metrics type mapping
+	_ = NewGateMetrics(mock{})
+
 	flag.Parse()
 
 	require.NotEmpty(t, metricsPath, "flag 'out' must be provided to dump metrics description")
 
-	data, err := json.Marshal(DescribeAll())
+	desc := DescribeAll()
+	data, err := json.Marshal(desc)
 	require.NoError(t, err)
 
 	err = os.WriteFile(*metricsPath, data, 0644)

metrics/metrics.go

@@ -56,6 +56,10 @@ const (
 	HealthStatusShuttingDown HealthStatus = 3
 )
 
+type StatisticScraper interface {
+	Statistic() pool.Statistic
+}
+
 type GateMetrics struct {
 	stateMetrics
 	poolMetricsCollector
@@ -67,7 +71,7 @@ type stateMetrics struct {
 }
 
 type poolMetricsCollector struct {
-	pool                *pool.Pool
+	scraper             StatisticScraper
 	overallErrors       prometheus.Gauge
 	overallNodeErrors   *prometheus.GaugeVec
 	overallNodeRequests *prometheus.GaugeVec
@@ -76,7 +80,7 @@ type poolMetricsCollector struct {
 }
 
 // NewGateMetrics creates new metrics for http gate.
-func NewGateMetrics(p *pool.Pool) *GateMetrics {
+func NewGateMetrics(p StatisticScraper) *GateMetrics {
 	stateMetric := newStateMetrics()
 	stateMetric.register()
 
@@ -96,8 +100,8 @@ func (g *GateMetrics) Unregister() {
 
 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]),
 	}
 }
 
@@ -119,14 +123,14 @@ func (m stateMetrics) SetVersion(ver string) {
 	m.versionInfo.WithLabelValues(ver).Set(1)
 }
 
-func newPoolMetricsCollector(p *pool.Pool) *poolMetricsCollector {
+func newPoolMetricsCollector(p StatisticScraper) *poolMetricsCollector {
 	return &poolMetricsCollector{
-		pool:                p,
+		scraper:             p,
-		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]),
 	}
 }
 
@@ -152,7 +156,7 @@ func (m *poolMetricsCollector) register() {
 }
 
 func (m *poolMetricsCollector) updateStatistic() {
-	stat := m.pool.Statistic()
+	stat := m.scraper.Statistic()
 
 	m.overallNodeErrors.Reset()
 	m.overallNodeRequests.Reset()