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/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,
+	})
+}