[#29] metrics: Support dump descriptions

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

Makefile

@@ -9,6 +9,8 @@ BUILD ?= $(shell date -u --iso=seconds)
 HUB_IMAGE ?= truecloudlab/frostfs-http-gw
 HUB_TAG ?= "$(shell echo ${VERSION} | sed 's/^v//')"
 
+METRICS_DUMP_OUT ?= ./metrics-dump.json
+
 # List of binaries to build. For now just one.
 BINDIR = bin
 DIRS = $(BINDIR)
@@ -143,4 +145,10 @@ debpackage:
 debclean:
 	dh clean
 
+# Dump metrics (use METRICS_DUMP_OUT variable to override default out file './metrics-dump.json')
+.PHONY: dump-metrics
+dump-metrics:
+	@go test ./metrics -run TestDescribeAll --tags=dump_metrics --out=$(abspath $(METRICS_DUMP_OUT))
+
+
 include help.mk

app.go

@@ -243,6 +243,17 @@ func (m *gateMetrics) SetHealth(status metrics.HealthStatus) {
 	m.provider.SetHealth(status)
 }
 
+func (m *gateMetrics) SetVersion(ver string) {
+	m.mu.RLock()
+	if !m.enabled {
+		m.mu.RUnlock()
+		return
+	}
+	m.mu.RUnlock()
+
+	m.provider.SetVersion(ver)
+}
+
 func (m *gateMetrics) Shutdown() {
 	m.mu.Lock()
 	if m.enabled {
@@ -325,6 +336,7 @@ func getKeyFromWallet(w *wallet.Wallet, addrStr string, password *string) (*ecds
 func (a *app) Wait() {
 	a.log.Info("starting application", zap.String("app_name", "frostfs-http-gw"), zap.String("version", Version))
 
+	a.metrics.SetVersion(Version)
 	a.setHealthStatus()
 
 	<-a.webDone // wait for web-server to be stopped

metrics/desc.go

@@ -0,0 +1,136 @@
+package metrics
+
+import (
+	"encoding/json"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+var appMetricsDesc = map[string]map[string]Description{
+	poolSubsystem: {
+		overallErrorsMetric: Description{
+			Namespace: namespace,
+			Subsystem: poolSubsystem,
+			Name:      overallErrorsMetric,
+			Help:      "Total number of errors in pool",
+		},
+		overallNodeErrorsMetric: Description{
+			Namespace:      namespace,
+			Subsystem:      poolSubsystem,
+			Name:           overallNodeErrorsMetric,
+			Help:           "Total number of errors for connection in pool",
+			VariableLabels: []string{"node"},
+		},
+		overallNodeRequestsMetric: Description{
+			Namespace:      namespace,
+			Subsystem:      poolSubsystem,
+			Name:           overallNodeRequestsMetric,
+			Help:           "Total number of requests to specific node in pool",
+			VariableLabels: []string{"node"},
+		},
+		currentErrorMetric: Description{
+			Namespace:      namespace,
+			Subsystem:      poolSubsystem,
+			Name:           currentErrorMetric,
+			Help:           "Number of errors on current connections that will be reset after the threshold",
+			VariableLabels: []string{"node"},
+		},
+		avgRequestDurationMetric: Description{
+			Namespace:      namespace,
+			Subsystem:      poolSubsystem,
+			Name:           avgRequestDurationMetric,
+			Help:           "Average request duration (in milliseconds) for specific method on node in pool",
+			VariableLabels: []string{"node", "method"},
+		},
+	},
+	stateSubsystem: {
+		healthMetric: Description{
+			Namespace: namespace,
+			Subsystem: stateSubsystem,
+			Name:      healthMetric,
+			Help:      "Current HTTP gateway state",
+		},
+		versionInfoMetric: Description{
+			Namespace:      namespace,
+			Subsystem:      stateSubsystem,
+			Name:           versionInfoMetric,
+			Help:           "Version of current FrostFS HTTP Gate instance",
+			VariableLabels: []string{"version"},
+		},
+	},
+}
+
+type Description struct {
+	Namespace      string
+	Subsystem      string
+	Name           string
+	Help           string
+	ConstantLabels []KeyValue
+	VariableLabels []string
+}
+
+type KeyValue struct {
+	Key   string `json:"key"`
+	Value string `json:"value"`
+}
+
+func (d *Description) MarshalJSON() ([]byte, error) {
+	return json.Marshal(&struct {
+		FQName         string     `json:"name"`
+		Help           string     `json:"help"`
+		ConstantLabels []KeyValue `json:"constant_labels"`
+		VariableLabels []string   `json:"variable_labels"`
+	}{
+		FQName:         d.BuildFQName(),
+		Help:           d.Help,
+		ConstantLabels: d.ConstantLabels,
+		VariableLabels: d.VariableLabels,
+	})
+}
+
+func (d *Description) BuildFQName() string {
+	return prometheus.BuildFQName(d.Namespace, d.Subsystem, d.Name)
+}
+
+func (d *Description) ConstLabelsMap() map[string]string {
+	constsLabels := make(map[string]string, len(d.ConstantLabels))
+	for _, kv := range d.ConstantLabels {
+		constsLabels[kv.Key] = kv.Value
+	}
+	return constsLabels
+}
+
+// DescribeAll returns descriptions for metrics.
+func DescribeAll() []Description {
+	var list []Description
+	for _, m := range appMetricsDesc {
+		for _, description := range m {
+			list = append(list, description)
+		}
+	}
+
+	return list
+}
+
+func newOpts(description Description) prometheus.Opts {
+	return prometheus.Opts{
+		Namespace:   description.Namespace,
+		Subsystem:   description.Subsystem,
+		Name:        description.Name,
+		Help:        description.Help,
+		ConstLabels: description.ConstLabelsMap(),
+	}
+}
+
+func newGauge(description Description) prometheus.Gauge {
+	return prometheus.NewGauge(
+		prometheus.GaugeOpts(newOpts(description)),
+	)
+}
+
+func newGaugeVec(description Description) *prometheus.GaugeVec {
+	return prometheus.NewGaugeVec(
+		prometheus.GaugeOpts(newOpts(description)),
+		description.VariableLabels,
+	)
+}

metrics/desc_test.go

@@ -0,0 +1,26 @@
+//go:build dump_metrics
+
+package metrics
+
+import (
+	"encoding/json"
+	"flag"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+var metricsPath = flag.String("out", "", "File to export http gateway metrics to.")
+
+func TestDescribeAll(t *testing.T) {
+	flag.Parse()
+
+	require.NotEmpty(t, metricsPath, "flag 'out' must be provided to dump metrics description")
+
+	data, err := json.Marshal(DescribeAll())
+	require.NoError(t, err)
+
+	err = os.WriteFile(*metricsPath, data, 0644)
+	require.NoError(t, err)
+}

metrics/metrics.go

@@ -13,7 +13,22 @@ const (
 	namespace      = "frostfs_http_gw"
 	stateSubsystem = "state"
 	poolSubsystem  = "pool"
+)
 
+const (
+	healthMetric      = "health"
+	versionInfoMetric = "version_info"
+)
+
+const (
+	overallErrorsMetric       = "overall_errors"
+	overallNodeErrorsMetric   = "overall_node_errors"
+	overallNodeRequestsMetric = "overall_node_requests"
+	currentErrorMetric        = "current_errors"
+	avgRequestDurationMetric  = "avg_request_duration"
+)
+
+const (
 	methodGetBalance       = "get_balance"
 	methodPutContainer     = "put_container"
 	methodGetContainer     = "get_container"
@@ -48,6 +63,7 @@ type GateMetrics struct {
 
 type stateMetrics struct {
 	healthCheck prometheus.Gauge
+	versionInfo *prometheus.GaugeVec
 }
 
 type poolMetricsCollector struct {
@@ -80,93 +96,37 @@ func (g *GateMetrics) Unregister() {
 
 func newStateMetrics() *stateMetrics {
 	return &stateMetrics{
-		healthCheck: prometheus.NewGauge(prometheus.GaugeOpts{
-			Namespace: namespace,
-			Subsystem: stateSubsystem,
-			Name:      "health",
-			Help:      "Current HTTP gateway state",
-		}),
+		healthCheck: newGauge(appMetricsDesc[stateSubsystem][healthMetric]),
+		versionInfo: newGaugeVec(appMetricsDesc[stateSubsystem][versionInfoMetric]),
 	}
 }
 
 func (m stateMetrics) register() {
 	prometheus.MustRegister(m.healthCheck)
+	prometheus.MustRegister(m.versionInfo)
 }
 
 func (m stateMetrics) unregister() {
 	prometheus.Unregister(m.healthCheck)
+	prometheus.Unregister(m.versionInfo)
 }
 
 func (m stateMetrics) SetHealth(s HealthStatus) {
 	m.healthCheck.Set(float64(s))
 }
 
+func (m stateMetrics) SetVersion(ver string) {
+	m.versionInfo.WithLabelValues(ver).Set(1)
+}
+
 func newPoolMetricsCollector(p *pool.Pool) *poolMetricsCollector {
-	overallErrors := prometheus.NewGauge(
-		prometheus.GaugeOpts{
-			Namespace: namespace,
-			Subsystem: poolSubsystem,
-			Name:      "overall_errors",
-			Help:      "Total number of errors in pool",
-		},
-	)
-
-	overallNodeErrors := prometheus.NewGaugeVec(
-		prometheus.GaugeOpts{
-			Namespace: namespace,
-			Subsystem: poolSubsystem,
-			Name:      "overall_node_errors",
-			Help:      "Total number of errors for connection in pool",
-		},
-		[]string{
-			"node",
-		},
-	)
-
-	overallNodeRequests := prometheus.NewGaugeVec(
-		prometheus.GaugeOpts{
-			Namespace: namespace,
-			Subsystem: poolSubsystem,
-			Name:      "overall_node_requests",
-			Help:      "Total number of requests to specific node in pool",
-		},
-		[]string{
-			"node",
-		},
-	)
-
-	currentErrors := prometheus.NewGaugeVec(
-		prometheus.GaugeOpts{
-			Namespace: namespace,
-			Subsystem: poolSubsystem,
-			Name:      "current_errors",
-			Help:      "Number of errors on current connections that will be reset after the threshold",
-		},
-		[]string{
-			"node",
-		},
-	)
-
-	requestsDuration := prometheus.NewGaugeVec(
-		prometheus.GaugeOpts{
-			Namespace: namespace,
-			Subsystem: poolSubsystem,
-			Name:      "avg_request_duration",
-			Help:      "Average request duration (in milliseconds) for specific method on node in pool",
-		},
-		[]string{
-			"node",
-			"method",
-		},
-	)
-
 	return &poolMetricsCollector{
 		pool:                p,
-		overallErrors:       overallErrors,
-		overallNodeErrors:   overallNodeErrors,
-		overallNodeRequests: overallNodeRequests,
-		currentErrors:       currentErrors,
-		requestDuration:     requestsDuration,
+		overallErrors:       newGauge(appMetricsDesc[poolSubsystem][overallErrorsMetric]),
+		overallNodeErrors:   newGaugeVec(appMetricsDesc[poolSubsystem][overallNodeErrorsMetric]),
+		overallNodeRequests: newGaugeVec(appMetricsDesc[poolSubsystem][overallNodeRequestsMetric]),
+		currentErrors:       newGaugeVec(appMetricsDesc[poolSubsystem][currentErrorMetric]),
+		requestDuration:     newGaugeVec(appMetricsDesc[poolSubsystem][avgRequestDurationMetric]),
 	}
 }