[#4] Export gRPC client and server metrics

Signed-off-by: Anton Nikiforov <an.nikiforov@yadro.com>

metrics/desc.go

@@ -21,7 +21,7 @@ type Description struct {
 // NewGauge returns new registered prometheus.Gauge.
 func NewGauge(opts prometheus.GaugeOpts) prometheus.Gauge {
 	value := prometheus.NewGauge(opts)
-	mustRegister(value, Description{
+	MustRegister(value, Description{
 		Name:           prometheus.BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
 		Type:           dto.MetricType_GAUGE.String(),
 		Help:           opts.Help,
@@ -33,7 +33,7 @@ func NewGauge(opts prometheus.GaugeOpts) prometheus.Gauge {
 // NewGaugeVec returns new registered *prometheus.GaugeVec.
 func NewGaugeVec(opts prometheus.GaugeOpts, labelNames []string) *prometheus.GaugeVec {
 	value := prometheus.NewGaugeVec(opts, labelNames)
-	mustRegister(value, Description{
+	MustRegister(value, Description{
 		Name:           prometheus.BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
 		Type:           dto.MetricType_GAUGE.String(),
 		Help:           opts.Help,
@@ -47,7 +47,7 @@ func NewGaugeVec(opts prometheus.GaugeOpts, labelNames []string) *prometheus.Gau
 // NewGaugeFunc returns new registered prometheus.GaugeFunc.
 func NewGaugeFunc(opts prometheus.GaugeOpts, f func() float64) prometheus.GaugeFunc {
 	value := prometheus.NewGaugeFunc(opts, f)
-	mustRegister(value, Description{
+	MustRegister(value, Description{
 		Name:           prometheus.BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
 		Type:           dto.MetricType_GAUGE.String(),
 		Help:           opts.Help,
@@ -59,7 +59,7 @@ func NewGaugeFunc(opts prometheus.GaugeOpts, f func() float64) prometheus.GaugeF
 // NewCounter returns new registered prometheus.Counter.
 func NewCounter(opts prometheus.CounterOpts) prometheus.Counter {
 	value := prometheus.NewCounter(opts)
-	mustRegister(value, Description{
+	MustRegister(value, Description{
 		Name:           prometheus.BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
 		Type:           dto.MetricType_COUNTER.String(),
 		Help:           opts.Help,
@@ -71,7 +71,7 @@ func NewCounter(opts prometheus.CounterOpts) prometheus.Counter {
 // NewCounterVec returns new registered *prometheus.CounterVec.
 func NewCounterVec(opts prometheus.CounterOpts, labels []string) *prometheus.CounterVec {
 	value := prometheus.NewCounterVec(opts, labels)
-	mustRegister(value, Description{
+	MustRegister(value, Description{
 		Name:           prometheus.BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
 		Type:           dto.MetricType_COUNTER.String(),
 		Help:           opts.Help,
@@ -84,7 +84,7 @@ func NewCounterVec(opts prometheus.CounterOpts, labels []string) *prometheus.Cou
 // NewHistogramVec returns new registered *prometheus.HistogramVec.
 func NewHistogramVec(opts prometheus.HistogramOpts, labelNames []string) *prometheus.HistogramVec {
 	value := prometheus.NewHistogramVec(opts, labelNames)
-	mustRegister(value, Description{
+	MustRegister(value, Description{
 		Name:           prometheus.BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
 		Type:           dto.MetricType_HISTOGRAM.String(),
 		Help:           opts.Help,

metrics/grpc/client.go

@@ -4,10 +4,11 @@ import (
 	"git.frostfs.info/TrueCloudLab/frostfs-observability/metrics"
 	grpcprom "github.com/grpc-ecosystem/go-grpc-middleware/providers/prometheus"
 	"github.com/prometheus/client_golang/prometheus"
+	dto "github.com/prometheus/client_model/go"
 	"google.golang.org/grpc"
 )
 
-var clientMetrics *grpcprom.ClientMetrics = grpcprom.NewClientMetrics(
+var clientMetrics = grpcprom.NewClientMetrics(
 	grpcprom.WithClientHandlingTimeHistogram(
 		grpcprom.WithHistogramBuckets(prometheus.DefBuckets),
 	),
@@ -17,7 +18,47 @@ var clientMetrics *grpcprom.ClientMetrics = grpcprom.NewClientMetrics(
 )
 
 func init() {
-	metrics.Register(clientMetrics)
+	// Description copied from repository of grpc-ecosystem
+	// https://github.com/grpc-ecosystem/go-grpc-middleware/blob/71d7422112b1d7fadd4b8bf12a6f33ba6d22e98e/providers/prometheus/client_metrics.go#L31
+	descs := []metrics.Description{
+		{
+			Name:           "grpc_client_started_total",
+			Type:           dto.MetricType_COUNTER.String(),
+			Help:           "Total number of RPCs started on the client.",
+			VariableLabels: []string{"grpc_type", "grpc_service", "grpc_method"},
+		},
+		{
+			Name:           "grpc_client_handled_total",
+			Type:           dto.MetricType_COUNTER.String(),
+			Help:           "Total number of RPCs completed by the client, regardless of success or failure.",
+			VariableLabels: []string{"grpc_type", "grpc_service", "grpc_method", "grpc_code"},
+		},
+		{
+			Name:           "grpc_client_msg_received_total",
+			Type:           dto.MetricType_COUNTER.String(),
+			Help:           "Total number of RPC stream messages received by the client.",
+			VariableLabels: []string{"grpc_type", "grpc_service", "grpc_method"},
+		},
+		{
+			Name:           "grpc_client_msg_sent_total",
+			Type:           dto.MetricType_COUNTER.String(),
+			Help:           "Total number of gRPC stream messages sent by the client.",
+			VariableLabels: []string{"grpc_type", "grpc_service", "grpc_method"},
+		},
+		{
+			Name:           "grpc_client_handling_seconds",
+			Type:           dto.MetricType_HISTOGRAM.String(),
+			Help:           "Histogram of response latency (seconds) of the gRPC until it is finished by the application.",
+			VariableLabels: []string{"grpc_type", "grpc_service", "grpc_method"},
+		},
+		{
+			Name:           "grpc_client_msg_recv_handling_seconds",
+			Type:           dto.MetricType_HISTOGRAM.String(),
+			Help:           "Histogram of response latency (seconds) of the gRPC single message receive.",
+			VariableLabels: []string{"grpc_type", "grpc_service", "grpc_method"},
+		},
+	}
+	metrics.MustRegister(clientMetrics, descs...)
 }
 
 // NewUnaryClientInterceptor returns client interceptor to collect metrics from unary RPCs.

metrics/grpc/server.go

@@ -4,17 +4,52 @@ import (
 	"git.frostfs.info/TrueCloudLab/frostfs-observability/metrics"
 	grpcprom "github.com/grpc-ecosystem/go-grpc-middleware/providers/prometheus"
 	"github.com/prometheus/client_golang/prometheus"
+	dto "github.com/prometheus/client_model/go"
 	"google.golang.org/grpc"
 )
 
-var serverMetrics *grpcprom.ServerMetrics = grpcprom.NewServerMetrics(
+var serverMetrics = grpcprom.NewServerMetrics(
 	grpcprom.WithServerHandlingTimeHistogram(
 		grpcprom.WithHistogramBuckets(prometheus.DefBuckets),
 	),
 )
 
 func init() {
-	metrics.Register(serverMetrics)
+	// Description copied from grpc-ecosystem:
+	// https://github.com/grpc-ecosystem/go-grpc-middleware/blob/71d7422112b1d7fadd4b8bf12a6f33ba6d22e98e/providers/prometheus/server_metrics.go#L26
+	descs := []metrics.Description{
+		{
+			Name:           "grpc_server_started_total",
+			Type:           dto.MetricType_COUNTER.String(),
+			Help:           "Total number of RPCs started on the server.",
+			VariableLabels: []string{"grpc_type", "grpc_service", "grpc_method"},
+		},
+		{
+			Name:           "grpc_server_handled_total",
+			Type:           dto.MetricType_COUNTER.String(),
+			Help:           "Total number of RPCs completed on the server, regardless of success or failure.",
+			VariableLabels: []string{"grpc_type", "grpc_service", "grpc_method", "grpc_code"},
+		},
+		{
+			Name:           "grpc_server_msg_received_total",
+			Type:           dto.MetricType_COUNTER.String(),
+			Help:           "Total number of RPC stream messages received on the server.",
+			VariableLabels: []string{"grpc_type", "grpc_service", "grpc_method"},
+		},
+		{
+			Name:           "grpc_server_msg_sent_total",
+			Type:           dto.MetricType_COUNTER.String(),
+			Help:           "Total number of gRPC stream messages sent by the server.",
+			VariableLabels: []string{"grpc_type", "grpc_service", "grpc_method"},
+		},
+		{
+			Name:           "grpc_server_handling_seconds",
+			Type:           dto.MetricType_HISTOGRAM.String(),
+			Help:           "Histogram of response latency (seconds) of gRPC that had been application-level handled by the server.",
+			VariableLabels: []string{"grpc_type", "grpc_service", "grpc_method"},
+		},
+	}
+	metrics.MustRegister(serverMetrics, descs...)
 }
 
 // NewUnaryServerInterceptor returns server interceptor to collect metrics from unary RPCs.

metrics/registry.go

@@ -28,11 +28,11 @@ func Register(customCollectors ...prometheus.Collector) {
 	registry.MustRegister(customCollectors...)
 }
 
-func mustRegister(c prometheus.Collector, desc Description) {
+func MustRegister(c prometheus.Collector, descs ...Description) {
 	registry.MustRegister(c)
 	registeredDescriptionsMtx.Lock()
 	defer registeredDescriptionsMtx.Unlock()
-	registeredDescriptions = append(registeredDescriptions, desc)
+	registeredDescriptions = append(registeredDescriptions, descs...)
 }
 
 // Handler returns an http.Handler for the local registry.