Add grpc prometheus metrics

This provideds generic grpc metrics via prometheus

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

vendor/github.com/grpc-ecosystem/go-grpc-prometheus/server_reporter.go

@@ -0,0 +1,157 @@
+// Copyright 2016 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+package grpc_prometheus
+
+import (
+	"time"
+
+	"google.golang.org/grpc/codes"
+
+	prom "github.com/prometheus/client_golang/prometheus"
+	"google.golang.org/grpc"
+)
+
+type grpcType string
+
+const (
+	Unary        grpcType = "unary"
+	ClientStream grpcType = "client_stream"
+	ServerStream grpcType = "server_stream"
+	BidiStream   grpcType = "bidi_stream"
+)
+
+var (
+	serverStartedCounter = prom.NewCounterVec(
+		prom.CounterOpts{
+			Namespace: "grpc",
+			Subsystem: "server",
+			Name:      "started_total",
+			Help:      "Total number of RPCs started on the server.",
+		}, []string{"grpc_type", "grpc_service", "grpc_method"})
+
+	serverHandledCounter = prom.NewCounterVec(
+		prom.CounterOpts{
+			Namespace: "grpc",
+			Subsystem: "server",
+			Name:      "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 = prom.NewCounterVec(
+		prom.CounterOpts{
+			Namespace: "grpc",
+			Subsystem: "server",
+			Name:      "msg_received_total",
+			Help:      "Total number of RPC stream messages received on the server.",
+		}, []string{"grpc_type", "grpc_service", "grpc_method"})
+
+	serverStreamMsgSent = prom.NewCounterVec(
+		prom.CounterOpts{
+			Namespace: "grpc",
+			Subsystem: "server",
+			Name:      "msg_sent_total",
+			Help:      "Total number of gRPC stream messages sent by the server.",
+		}, []string{"grpc_type", "grpc_service", "grpc_method"})
+
+	serverHandledHistogramEnabled = false
+	serverHandledHistogramOpts    = prom.HistogramOpts{
+		Namespace: "grpc",
+		Subsystem: "server",
+		Name:      "handling_seconds",
+		Help:      "Histogram of response latency (seconds) of gRPC that had been application-level handled by the server.",
+		Buckets:   prom.DefBuckets,
+	}
+	serverHandledHistogram *prom.HistogramVec
+)
+
+func init() {
+	prom.MustRegister(serverStartedCounter)
+	prom.MustRegister(serverHandledCounter)
+	prom.MustRegister(serverStreamMsgReceived)
+	prom.MustRegister(serverStreamMsgSent)
+}
+
+type HistogramOption func(*prom.HistogramOpts)
+
+// WithHistogramBuckets allows you to specify custom bucket ranges for histograms if EnableHandlingTimeHistogram is on.
+func WithHistogramBuckets(buckets []float64) HistogramOption {
+	return func(o *prom.HistogramOpts) { o.Buckets = buckets }
+}
+
+// EnableHandlingTimeHistogram turns on recording of handling time of RPCs for server-side interceptors.
+// Histogram metrics can be very expensive for Prometheus to retain and query.
+func EnableHandlingTimeHistogram(opts ...HistogramOption) {
+	for _, o := range opts {
+		o(&serverHandledHistogramOpts)
+	}
+	if !serverHandledHistogramEnabled {
+		serverHandledHistogram = prom.NewHistogramVec(
+			serverHandledHistogramOpts,
+			[]string{"grpc_type", "grpc_service", "grpc_method"},
+		)
+		prom.Register(serverHandledHistogram)
+	}
+	serverHandledHistogramEnabled = true
+}
+
+type serverReporter struct {
+	rpcType     grpcType
+	serviceName string
+	methodName  string
+	startTime   time.Time
+}
+
+func newServerReporter(rpcType grpcType, fullMethod string) *serverReporter {
+	r := &serverReporter{rpcType: rpcType}
+	if serverHandledHistogramEnabled {
+		r.startTime = time.Now()
+	}
+	r.serviceName, r.methodName = splitMethodName(fullMethod)
+	serverStartedCounter.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName).Inc()
+	return r
+}
+
+func (r *serverReporter) ReceivedMessage() {
+	serverStreamMsgReceived.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName).Inc()
+}
+
+func (r *serverReporter) SentMessage() {
+	serverStreamMsgSent.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName).Inc()
+}
+
+func (r *serverReporter) Handled(code codes.Code) {
+	serverHandledCounter.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName, code.String()).Inc()
+	if serverHandledHistogramEnabled {
+		serverHandledHistogram.WithLabelValues(string(r.rpcType), r.serviceName, r.methodName).Observe(time.Since(r.startTime).Seconds())
+	}
+}
+
+// preRegisterMethod is invoked on Register of a Server, allowing all gRPC services labels to be pre-populated.
+func 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.
+	serverStartedCounter.GetMetricWithLabelValues(methodType, serviceName, methodName)
+	serverStreamMsgReceived.GetMetricWithLabelValues(methodType, serviceName, methodName)
+	serverStreamMsgSent.GetMetricWithLabelValues(methodType, serviceName, methodName)
+	if serverHandledHistogramEnabled {
+		serverHandledHistogram.GetMetricWithLabelValues(methodType, serviceName, methodName)
+	}
+	for _, code := range allCodes {
+		serverHandledCounter.GetMetricWithLabelValues(methodType, serviceName, methodName, code.String())
+	}
+}
+
+func typeFromMethodInfo(mInfo *grpc.MethodInfo) grpcType {
+	if mInfo.IsClientStream == false && mInfo.IsServerStream == false {
+		return Unary
+	}
+	if mInfo.IsClientStream == true && mInfo.IsServerStream == false {
+		return ClientStream
+	}
+	if mInfo.IsClientStream == false && mInfo.IsServerStream == true {
+		return ServerStream
+	}
+	return BidiStream
+}