Replace go-grpc-prometheus with go-grpc-middleware/providers/prometheus

Fixes #9806

go-grpc-prometheus is deprecated. The new location it was moved to also introduced
an entirely new api, but afaict this matches what we have at the moment.

Signed-off-by: Danny Canter <danny@dcantah.dev>

vendor/github.com/grpc-ecosystem/go-grpc-middleware/providers/prometheus/LICENSE

@@ -0,0 +1,201 @@
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vendor/github.com/grpc-ecosystem/go-grpc-middleware/providers/prometheus/client_metrics.go

@@ -0,0 +1,117 @@
+// Copyright (c) The go-grpc-middleware Authors.
+// Licensed under the Apache License 2.0.
+
+package prometheus
+
+import (
+	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors"
+	"github.com/prometheus/client_golang/prometheus"
+	"google.golang.org/grpc"
+)
+
+// ClientMetrics represents a collection of metrics to be registered on a
+// Prometheus metrics registry for a gRPC client.
+type ClientMetrics struct {
+	clientStartedCounter    *prometheus.CounterVec
+	clientHandledCounter    *prometheus.CounterVec
+	clientStreamMsgReceived *prometheus.CounterVec
+	clientStreamMsgSent     *prometheus.CounterVec
+
+	// clientHandledHistogram can be nil
+	clientHandledHistogram *prometheus.HistogramVec
+	// clientStreamRecvHistogram can be nil
+	clientStreamRecvHistogram *prometheus.HistogramVec
+	// clientStreamSendHistogram can be nil
+	clientStreamSendHistogram *prometheus.HistogramVec
+}
+
+// NewClientMetrics returns a new ClientMetrics object.
+// NOTE: Remember to register ClientMetrics object using prometheus registry
+// e.g. prometheus.MustRegister(myClientMetrics).
+func NewClientMetrics(opts ...ClientMetricsOption) *ClientMetrics {
+	var config clientMetricsConfig
+	config.apply(opts)
+	return &ClientMetrics{
+		clientStartedCounter: prometheus.NewCounterVec(
+			config.counterOpts.apply(prometheus.CounterOpts{
+				Name: "grpc_client_started_total",
+				Help: "Total number of RPCs started on the client.",
+			}), []string{"grpc_type", "grpc_service", "grpc_method"}),
+
+		clientHandledCounter: prometheus.NewCounterVec(
+			config.counterOpts.apply(prometheus.CounterOpts{
+				Name: "grpc_client_handled_total",
+				Help: "Total number of RPCs completed by the client, regardless of success or failure.",
+			}), []string{"grpc_type", "grpc_service", "grpc_method", "grpc_code"}),
+
+		clientStreamMsgReceived: prometheus.NewCounterVec(
+			config.counterOpts.apply(prometheus.CounterOpts{
+				Name: "grpc_client_msg_received_total",
+				Help: "Total number of RPC stream messages received by the client.",
+			}), []string{"grpc_type", "grpc_service", "grpc_method"}),
+
+		clientStreamMsgSent: prometheus.NewCounterVec(
+			config.counterOpts.apply(prometheus.CounterOpts{
+				Name: "grpc_client_msg_sent_total",
+				Help: "Total number of gRPC stream messages sent by the client.",
+			}), []string{"grpc_type", "grpc_service", "grpc_method"}),
+
+		clientHandledHistogram:    config.clientHandledHistogram,
+		clientStreamRecvHistogram: config.clientStreamRecvHistogram,
+		clientStreamSendHistogram: config.clientStreamSendHistogram,
+	}
+}
+
+// Describe sends the super-set of all possible descriptors of metrics
+// collected by this Collector to the provided channel and returns once
+// the last descriptor has been sent.
+func (m *ClientMetrics) Describe(ch chan<- *prometheus.Desc) {
+	m.clientStartedCounter.Describe(ch)
+	m.clientHandledCounter.Describe(ch)
+	m.clientStreamMsgReceived.Describe(ch)
+	m.clientStreamMsgSent.Describe(ch)
+	if m.clientHandledHistogram != nil {
+		m.clientHandledHistogram.Describe(ch)
+	}
+	if m.clientStreamRecvHistogram != nil {
+		m.clientStreamRecvHistogram.Describe(ch)
+	}
+	if m.clientStreamSendHistogram != nil {
+		m.clientStreamSendHistogram.Describe(ch)
+	}
+}
+
+// Collect is called by the Prometheus registry when collecting
+// metrics. The implementation sends each collected metric via the
+// provided channel and returns once the last metric has been sent.
+func (m *ClientMetrics) Collect(ch chan<- prometheus.Metric) {
+	m.clientStartedCounter.Collect(ch)
+	m.clientHandledCounter.Collect(ch)
+	m.clientStreamMsgReceived.Collect(ch)
+	m.clientStreamMsgSent.Collect(ch)
+	if m.clientHandledHistogram != nil {
+		m.clientHandledHistogram.Collect(ch)
+	}
+	if m.clientStreamRecvHistogram != nil {
+		m.clientStreamRecvHistogram.Collect(ch)
+	}
+	if m.clientStreamSendHistogram != nil {
+		m.clientStreamSendHistogram.Collect(ch)
+	}
+}
+
+// UnaryClientInterceptor is a gRPC client-side interceptor that provides Prometheus monitoring for Unary RPCs.
+func (m *ClientMetrics) UnaryClientInterceptor(opts ...Option) grpc.UnaryClientInterceptor {
+	return interceptors.UnaryClientInterceptor(&reportable{
+		opts:          opts,
+		clientMetrics: m,
+	})
+}
+
+// StreamClientInterceptor is a gRPC client-side interceptor that provides Prometheus monitoring for Streaming RPCs.
+func (m *ClientMetrics) StreamClientInterceptor(opts ...Option) grpc.StreamClientInterceptor {
+	return interceptors.StreamClientInterceptor(&reportable{
+		opts:          opts,
+		clientMetrics: m,
+	})
+}

vendor/github.com/grpc-ecosystem/go-grpc-middleware/providers/prometheus/client_options.go

@@ -0,0 +1,77 @@
+// Copyright (c) The go-grpc-middleware Authors.
+// Licensed under the Apache License 2.0.
+
+package prometheus
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type clientMetricsConfig struct {
+	counterOpts counterOptions
+	// clientHandledHistogram can be nil.
+	clientHandledHistogram *prometheus.HistogramVec
+	// clientStreamRecvHistogram can be nil.
+	clientStreamRecvHistogram *prometheus.HistogramVec
+	// clientStreamSendHistogram can be nil.
+	clientStreamSendHistogram *prometheus.HistogramVec
+}
+
+type ClientMetricsOption func(*clientMetricsConfig)
+
+func (c *clientMetricsConfig) apply(opts []ClientMetricsOption) {
+	for _, o := range opts {
+		o(c)
+	}
+}
+
+func WithClientCounterOptions(opts ...CounterOption) ClientMetricsOption {
+	return func(o *clientMetricsConfig) {
+		o.counterOpts = opts
+	}
+}
+
+// WithClientHandlingTimeHistogram turns on recording of handling time of RPCs.
+// Histogram metrics can be very expensive for Prometheus to retain and query.
+func WithClientHandlingTimeHistogram(opts ...HistogramOption) ClientMetricsOption {
+	return func(o *clientMetricsConfig) {
+		o.clientHandledHistogram = prometheus.NewHistogramVec(
+			histogramOptions(opts).apply(prometheus.HistogramOpts{
+				Name:    "grpc_client_handling_seconds",
+				Help:    "Histogram of response latency (seconds) of the gRPC until it is finished by the application.",
+				Buckets: prometheus.DefBuckets,
+			}),
+			[]string{"grpc_type", "grpc_service", "grpc_method"},
+		)
+	}
+}
+
+// WithClientStreamRecvHistogram turns on recording of single message receive time of streaming RPCs.
+// Histogram metrics can be very expensive for Prometheus to retain and query.
+func WithClientStreamRecvHistogram(opts ...HistogramOption) ClientMetricsOption {
+	return func(o *clientMetricsConfig) {
+		o.clientStreamRecvHistogram = prometheus.NewHistogramVec(
+			histogramOptions(opts).apply(prometheus.HistogramOpts{
+				Name:    "grpc_client_msg_recv_handling_seconds",
+				Help:    "Histogram of response latency (seconds) of the gRPC single message receive.",
+				Buckets: prometheus.DefBuckets,
+			}),
+			[]string{"grpc_type", "grpc_service", "grpc_method"},
+		)
+	}
+}
+
+// WithClientStreamSendHistogram turns on recording of single message send time of streaming RPCs.
+// Histogram metrics can be very expensive for Prometheus to retain and query.
+func WithClientStreamSendHistogram(opts ...HistogramOption) ClientMetricsOption {
+	return func(o *clientMetricsConfig) {
+		o.clientStreamSendHistogram = prometheus.NewHistogramVec(
+			histogramOptions(opts).apply(prometheus.HistogramOpts{
+				Name:    "grpc_client_msg_send_handling_seconds",
+				Help:    "Histogram of response latency (seconds) of the gRPC single message send.",
+				Buckets: prometheus.DefBuckets,
+			}),
+			[]string{"grpc_type", "grpc_service", "grpc_method"},
+		)
+	}
+}

vendor/github.com/grpc-ecosystem/go-grpc-middleware/providers/prometheus/constants.go

@@ -0,0 +1,23 @@
+// Copyright (c) The go-grpc-middleware Authors.
+// Licensed under the Apache License 2.0.
+
+package prometheus
+
+type grpcType string
+
+// grpcType describes all types of grpc connection.
+const (
+	Unary        grpcType = "unary"
+	ClientStream grpcType = "client_stream"
+	ServerStream grpcType = "server_stream"
+	BidiStream   grpcType = "bidi_stream"
+)
+
+// Kind describes whether interceptor is a client or server type.
+type Kind string
+
+// Enum for Client and Server Kind.
+const (
+	KindClient Kind = "client"
+	KindServer Kind = "server"
+)

vendor/github.com/grpc-ecosystem/go-grpc-middleware/providers/prometheus/doc.go

@@ -0,0 +1,8 @@
+// Copyright (c) The go-grpc-middleware Authors.
+// Licensed under the Apache License 2.0.
+
+/*
+Package prometheus provides a standalone interceptor for metrics. It's next iteration of deprecated https://github.com/grpc-ecosystem/go-grpc-prometheus.
+See https://github.com/grpc-ecosystem/go-grpc-middleware/tree/main/examples for example.
+*/
+package prometheus

vendor/github.com/grpc-ecosystem/go-grpc-middleware/providers/prometheus/options.go

@@ -0,0 +1,129 @@
+// Copyright (c) The go-grpc-middleware Authors.
+// Licensed under the Apache License 2.0.
+
+package prometheus
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/status"
+)
+
+// FromError returns a grpc status. If the error code is neither a valid grpc status nor a context error, codes.Unknown
+// will be set.
+func FromError(err error) *status.Status {
+	s, ok := status.FromError(err)
+	// Mirror what the grpc server itself does, i.e. also convert context errors to status
+	if !ok {
+		s = status.FromContextError(err)
+	}
+	return s
+}
+
+// A CounterOption lets you add options to Counter metrics using With* funcs.
+type CounterOption func(*prometheus.CounterOpts)
+
+type counterOptions []CounterOption
+
+func (co counterOptions) apply(o prometheus.CounterOpts) prometheus.CounterOpts {
+	for _, f := range co {
+		f(&o)
+	}
+	return o
+}
+
+// WithConstLabels allows you to add ConstLabels to Counter metrics.
+func WithConstLabels(labels prometheus.Labels) CounterOption {
+	return func(o *prometheus.CounterOpts) {
+		o.ConstLabels = labels
+	}
+}
+
+// WithSubsystem allows you to add a Subsystem to Counter metrics.
+func WithSubsystem(subsystem string) CounterOption {
+	return func(o *prometheus.CounterOpts) {
+		o.Subsystem = subsystem
+	}
+}
+
+// A HistogramOption lets you add options to Histogram metrics using With*
+// funcs.
+type HistogramOption func(*prometheus.HistogramOpts)
+
+type histogramOptions []HistogramOption
+
+func (ho histogramOptions) apply(o prometheus.HistogramOpts) prometheus.HistogramOpts {
+	for _, f := range ho {
+		f(&o)
+	}
+	return o
+}
+
+// WithHistogramBuckets allows you to specify custom bucket ranges for histograms if EnableHandlingTimeHistogram is on.
+func WithHistogramBuckets(buckets []float64) HistogramOption {
+	return func(o *prometheus.HistogramOpts) { o.Buckets = buckets }
+}
+
+// WithHistogramOpts allows you to specify HistogramOpts but makes sure the correct name and label is used.
+// This function is helpful when specifying more than just the buckets, like using NativeHistograms.
+func WithHistogramOpts(opts *prometheus.HistogramOpts) HistogramOption {
+	// TODO: This isn't ideal either if new fields are added to prometheus.HistogramOpts.
+	// Maybe we can change the interface to accept abitrary HistogramOpts and
+	// only make sure to overwrite the necessary fields (name, labels).
+	return func(o *prometheus.HistogramOpts) {
+		o.Buckets = opts.Buckets
+		o.NativeHistogramBucketFactor = opts.NativeHistogramBucketFactor
+		o.NativeHistogramZeroThreshold = opts.NativeHistogramZeroThreshold
+		o.NativeHistogramMaxBucketNumber = opts.NativeHistogramMaxBucketNumber
+		o.NativeHistogramMinResetDuration = opts.NativeHistogramMinResetDuration
+		o.NativeHistogramMaxZeroThreshold = opts.NativeHistogramMaxZeroThreshold
+	}
+}
+
+// WithHistogramConstLabels allows you to add custom ConstLabels to
+// histograms metrics.
+func WithHistogramConstLabels(labels prometheus.Labels) HistogramOption {
+	return func(o *prometheus.HistogramOpts) {
+		o.ConstLabels = labels
+	}
+}
+
+// WithHistogramSubsystem allows you to add a Subsystem to histograms metrics.
+func WithHistogramSubsystem(subsystem string) HistogramOption {
+	return func(o *prometheus.HistogramOpts) {
+		o.Subsystem = subsystem
+	}
+}
+
+func typeFromMethodInfo(mInfo *grpc.MethodInfo) grpcType {
+	if !mInfo.IsClientStream && !mInfo.IsServerStream {
+		return Unary
+	}
+	if mInfo.IsClientStream && !mInfo.IsServerStream {
+		return ClientStream
+	}
+	if !mInfo.IsClientStream && mInfo.IsServerStream {
+		return ServerStream
+	}
+	return BidiStream
+}
+
+// An Option lets you add options to prometheus interceptors using With* funcs.
+type Option func(*config)
+
+type config struct {
+	exemplarFn exemplarFromCtxFn
+}
+
+func (c *config) apply(opts []Option) {
+	for _, o := range opts {
+		o(c)
+	}
+}
+
+// WithExemplarFromContext sets function that will be used to deduce exemplar for all counter and histogram metrics.
+func WithExemplarFromContext(exemplarFn exemplarFromCtxFn) Option {
+	return func(o *config) {
+		o.exemplarFn = exemplarFn
+	}
+}

vendor/github.com/grpc-ecosystem/go-grpc-middleware/providers/prometheus/reporter.go

@@ -0,0 +1,113 @@
+// Copyright (c) The go-grpc-middleware Authors.
+// Licensed under the Apache License 2.0.
+
+package prometheus
+
+import (
+	"context"
+	"time"
+
+	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type reporter struct {
+	clientMetrics   *ClientMetrics
+	serverMetrics   *ServerMetrics
+	typ             interceptors.GRPCType
+	service, method string
+	kind            Kind
+	exemplar        prometheus.Labels
+}
+
+func (r *reporter) PostCall(err error, rpcDuration time.Duration) {
+	// get status code from error
+	status := FromError(err)
+	code := status.Code()
+
+	// perform handling of metrics from code
+	switch r.kind {
+	case KindServer:
+		r.incrementWithExemplar(r.serverMetrics.serverHandledCounter, string(r.typ), r.service, r.method, code.String())
+		if r.serverMetrics.serverHandledHistogram != nil {
+			r.observeWithExemplar(r.serverMetrics.serverHandledHistogram, rpcDuration.Seconds(), string(r.typ), r.service, r.method)
+		}
+
+	case KindClient:
+		r.incrementWithExemplar(r.clientMetrics.clientHandledCounter, string(r.typ), r.service, r.method, code.String())
+		if r.clientMetrics.clientHandledHistogram != nil {
+			r.observeWithExemplar(r.clientMetrics.clientHandledHistogram, rpcDuration.Seconds(), string(r.typ), r.service, r.method)
+		}
+	}
+}
+
+func (r *reporter) PostMsgSend(_ any, _ error, sendDuration time.Duration) {
+	switch r.kind {
+	case KindServer:
+		r.incrementWithExemplar(r.serverMetrics.serverStreamMsgSent, string(r.typ), r.service, r.method)
+	case KindClient:
+		r.incrementWithExemplar(r.clientMetrics.clientStreamMsgSent, string(r.typ), r.service, r.method)
+		if r.clientMetrics.clientStreamSendHistogram != nil {
+			r.observeWithExemplar(r.clientMetrics.clientStreamSendHistogram, sendDuration.Seconds(), string(r.typ), r.service, r.method)
+		}
+	}
+}
+
+func (r *reporter) PostMsgReceive(_ any, _ error, recvDuration time.Duration) {
+	switch r.kind {
+	case KindServer:
+		r.incrementWithExemplar(r.serverMetrics.serverStreamMsgReceived, string(r.typ), r.service, r.method)
+	case KindClient:
+		r.incrementWithExemplar(r.clientMetrics.clientStreamMsgReceived, string(r.typ), r.service, r.method)
+		if r.clientMetrics.clientStreamRecvHistogram != nil {
+			r.observeWithExemplar(r.clientMetrics.clientStreamRecvHistogram, recvDuration.Seconds(), string(r.typ), r.service, r.method)
+		}
+	}
+}
+
+type reportable struct {
+	clientMetrics *ClientMetrics
+	serverMetrics *ServerMetrics
+
+	opts []Option
+}
+
+func (rep *reportable) ServerReporter(ctx context.Context, meta interceptors.CallMeta) (interceptors.Reporter, context.Context) {
+	return rep.reporter(ctx, rep.serverMetrics, nil, meta, KindServer)
+}
+
+func (rep *reportable) ClientReporter(ctx context.Context, meta interceptors.CallMeta) (interceptors.Reporter, context.Context) {
+	return rep.reporter(ctx, nil, rep.clientMetrics, meta, KindClient)
+}
+
+func (rep *reportable) reporter(ctx context.Context, sm *ServerMetrics, cm *ClientMetrics, meta interceptors.CallMeta, kind Kind) (interceptors.Reporter, context.Context) {
+	var c config
+	c.apply(rep.opts)
+	r := &reporter{
+		clientMetrics: cm,
+		serverMetrics: sm,
+		typ:           meta.Typ,
+		service:       meta.Service,
+		method:        meta.Method,
+		kind:          kind,
+	}
+	if c.exemplarFn != nil {
+		r.exemplar = c.exemplarFn(ctx)
+	}
+
+	switch kind {
+	case KindClient:
+		r.incrementWithExemplar(r.clientMetrics.clientStartedCounter, string(r.typ), r.service, r.method)
+	case KindServer:
+		r.incrementWithExemplar(r.serverMetrics.serverStartedCounter, string(r.typ), r.service, r.method)
+	}
+	return r, ctx
+}
+
+func (r *reporter) incrementWithExemplar(c *prometheus.CounterVec, lvals ...string) {
+	c.WithLabelValues(lvals...).(prometheus.ExemplarAdder).AddWithExemplar(1, r.exemplar)
+}
+
+func (r *reporter) observeWithExemplar(h *prometheus.HistogramVec, value float64, lvals ...string) {
+	h.WithLabelValues(lvals...).(prometheus.ExemplarObserver).ObserveWithExemplar(value, r.exemplar)
+}

vendor/github.com/grpc-ecosystem/go-grpc-middleware/providers/prometheus/server_metrics.go

@@ -0,0 +1,123 @@
+// Copyright (c) The go-grpc-middleware Authors.
+// Licensed under the Apache License 2.0.
+
+package prometheus
+
+import (
+	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors"
+	"github.com/prometheus/client_golang/prometheus"
+	"google.golang.org/grpc"
+)
+
+// ServerMetrics represents a collection of metrics to be registered on a
+// Prometheus metrics registry for a gRPC server.
+type ServerMetrics struct {
+	serverStartedCounter    *prometheus.CounterVec
+	serverHandledCounter    *prometheus.CounterVec
+	serverStreamMsgReceived *prometheus.CounterVec
+	serverStreamMsgSent     *prometheus.CounterVec
+	// serverHandledHistogram can be nil.
+	serverHandledHistogram *prometheus.HistogramVec
+}
+
+// NewServerMetrics returns a new ServerMetrics object that has server interceptor methods.
+// NOTE: Remember to register ServerMetrics object by using prometheus registry
+// e.g. prometheus.MustRegister(myServerMetrics).
+func NewServerMetrics(opts ...ServerMetricsOption) *ServerMetrics {
+	var config serverMetricsConfig
+	config.apply(opts)
+	return &ServerMetrics{
+		serverStartedCounter: prometheus.NewCounterVec(
+			config.counterOpts.apply(prometheus.CounterOpts{
+				Name: "grpc_server_started_total",
+				Help: "Total number of RPCs started on the server.",
+			}), []string{"grpc_type", "grpc_service", "grpc_method"}),
+		serverHandledCounter: prometheus.NewCounterVec(
+			config.counterOpts.apply(prometheus.CounterOpts{
+				Name: "grpc_server_handled_total",
+				Help: "Total number of RPCs completed on the server, regardless of success or failure.",
+			}), []string{"grpc_type", "grpc_service", "grpc_method", "grpc_code"}),
+		serverStreamMsgReceived: prometheus.NewCounterVec(
+			config.counterOpts.apply(prometheus.CounterOpts{
+				Name: "grpc_server_msg_received_total",
+				Help: "Total number of RPC stream messages received on the server.",
+			}), []string{"grpc_type", "grpc_service", "grpc_method"}),
+		serverStreamMsgSent: prometheus.NewCounterVec(
+			config.counterOpts.apply(prometheus.CounterOpts{
+				Name: "grpc_server_msg_sent_total",
+				Help: "Total number of gRPC stream messages sent by the server.",
+			}), []string{"grpc_type", "grpc_service", "grpc_method"}),
+		serverHandledHistogram: config.serverHandledHistogram,
+	}
+}
+
+// Describe sends the super-set of all possible descriptors of metrics
+// collected by this Collector to the provided channel and returns once
+// the last descriptor has been sent.
+func (m *ServerMetrics) Describe(ch chan<- *prometheus.Desc) {
+	m.serverStartedCounter.Describe(ch)
+	m.serverHandledCounter.Describe(ch)
+	m.serverStreamMsgReceived.Describe(ch)
+	m.serverStreamMsgSent.Describe(ch)
+	if m.serverHandledHistogram != nil {
+		m.serverHandledHistogram.Describe(ch)
+	}
+}
+
+// Collect is called by the Prometheus registry when collecting
+// metrics. The implementation sends each collected metric via the
+// provided channel and returns once the last metric has been sent.
+func (m *ServerMetrics) Collect(ch chan<- prometheus.Metric) {
+	m.serverStartedCounter.Collect(ch)
+	m.serverHandledCounter.Collect(ch)
+	m.serverStreamMsgReceived.Collect(ch)
+	m.serverStreamMsgSent.Collect(ch)
+	if m.serverHandledHistogram != nil {
+		m.serverHandledHistogram.Collect(ch)
+	}
+}
+
+// InitializeMetrics initializes all metrics, with their appropriate null
+// value, for all gRPC methods registered on a gRPC server. This is useful, to
+// ensure that all metrics exist when collecting and querying.
+// NOTE: This might add significant cardinality and might not be needed in future version of Prometheus (created timestamp).
+func (m *ServerMetrics) InitializeMetrics(server *grpc.Server) {
+	serviceInfo := server.GetServiceInfo()
+	for serviceName, info := range serviceInfo {
+		for _, mInfo := range info.Methods {
+			m.preRegisterMethod(serviceName, &mInfo)
+		}
+	}
+}
+
+// preRegisterMethod is invoked on Register of a Server, allowing all gRPC services labels to be pre-populated.
+func (m *ServerMetrics) preRegisterMethod(serviceName string, mInfo *grpc.MethodInfo) {
+	methodName := mInfo.Name
+	methodType := string(typeFromMethodInfo(mInfo))
+	// These are just references (no increments), as just referencing will create the labels but not set values.
+	_, _ = m.serverStartedCounter.GetMetricWithLabelValues(methodType, serviceName, methodName)
+	_, _ = m.serverStreamMsgReceived.GetMetricWithLabelValues(methodType, serviceName, methodName)
+	_, _ = m.serverStreamMsgSent.GetMetricWithLabelValues(methodType, serviceName, methodName)
+	if m.serverHandledHistogram != nil {
+		_, _ = m.serverHandledHistogram.GetMetricWithLabelValues(methodType, serviceName, methodName)
+	}
+	for _, code := range interceptors.AllCodes {
+		_, _ = m.serverHandledCounter.GetMetricWithLabelValues(methodType, serviceName, methodName, code.String())
+	}
+}
+
+// UnaryServerInterceptor is a gRPC server-side interceptor that provides Prometheus monitoring for Unary RPCs.
+func (m *ServerMetrics) UnaryServerInterceptor(opts ...Option) grpc.UnaryServerInterceptor {
+	return interceptors.UnaryServerInterceptor(&reportable{
+		opts:          opts,
+		serverMetrics: m,
+	})
+}
+
+// StreamServerInterceptor is a gRPC server-side interceptor that provides Prometheus monitoring for Streaming RPCs.
+func (m *ServerMetrics) StreamServerInterceptor(opts ...Option) grpc.StreamServerInterceptor {
+	return interceptors.StreamServerInterceptor(&reportable{
+		opts:          opts,
+		serverMetrics: m,
+	})
+}

vendor/github.com/grpc-ecosystem/go-grpc-middleware/providers/prometheus/server_options.go

@@ -0,0 +1,48 @@
+// Copyright (c) The go-grpc-middleware Authors.
+// Licensed under the Apache License 2.0.
+
+package prometheus
+
+import (
+	"context"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type exemplarFromCtxFn func(ctx context.Context) prometheus.Labels
+
+type serverMetricsConfig struct {
+	counterOpts counterOptions
+	// serverHandledHistogram can be nil.
+	serverHandledHistogram *prometheus.HistogramVec
+}
+
+type ServerMetricsOption func(*serverMetricsConfig)
+
+func (c *serverMetricsConfig) apply(opts []ServerMetricsOption) {
+	for _, o := range opts {
+		o(c)
+	}
+}
+
+// WithServerCounterOptions sets counter options.
+func WithServerCounterOptions(opts ...CounterOption) ServerMetricsOption {
+	return func(o *serverMetricsConfig) {
+		o.counterOpts = opts
+	}
+}
+
+// WithServerHandlingTimeHistogram turns on recording of handling time of RPCs.
+// Histogram metrics can be very expensive for Prometheus to retain and query.
+func WithServerHandlingTimeHistogram(opts ...HistogramOption) ServerMetricsOption {
+	return func(o *serverMetricsConfig) {
+		o.serverHandledHistogram = prometheus.NewHistogramVec(
+			histogramOptions(opts).apply(prometheus.HistogramOpts{
+				Name:    "grpc_server_handling_seconds",
+				Help:    "Histogram of response latency (seconds) of gRPC that had been application-level handled by the server.",
+				Buckets: prometheus.DefBuckets,
+			}),
+			[]string{"grpc_type", "grpc_service", "grpc_method"},
+		)
+	}
+}