Add an option to expose Prometheus metrics via http/s server

go.mod

@@ -14,6 +14,7 @@ require (
 	github.com/networkservicemesh/sdk v0.5.1-0.20240820090035-6fad31a9f0aa
 	github.com/networkservicemesh/sdk-kernel v0.0.0-20240820090342-573b7f288d21
 	github.com/pkg/errors v0.9.1
+	github.com/prometheus/client_golang v1.17.0
 	github.com/stretchr/testify v1.8.4
 	github.com/vishvananda/netlink v1.2.1-beta.2.0.20220630165224-c591ada0fb2b
 	github.com/vishvananda/netns v0.0.0-20211101163701-50045581ed74
@@ -52,7 +53,6 @@ require (
 	github.com/matttproud/golang_protobuf_extensions v1.0.4 // indirect
 	github.com/open-policy-agent/opa v0.44.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	github.com/prometheus/client_golang v1.17.0 // indirect
 	github.com/prometheus/client_model v0.5.0 // indirect
 	github.com/prometheus/common v0.44.0 // indirect
 	github.com/prometheus/procfs v0.11.1 // indirect

pkg/networkservice/metrics/stats/client.go

@@ -44,6 +44,7 @@ type statsClient struct {
 
 // NewClient provides a NetworkServiceClient chain elements that retrieves vpp interface metrics.
 func NewClient(ctx context.Context, options ...Option) networkservice.NetworkServiceClient {
+	prometheusInitOnce.Do(registerMetrics)
 	opts := &statsOptions{}
 	for _, opt := range options {
 		opt(opts)

pkg/networkservice/metrics/stats/common.go

@@ -32,11 +32,14 @@ import (
 
 	"github.com/networkservicemesh/api/pkg/api/networkservice"
 	"github.com/networkservicemesh/sdk/pkg/tools/log"
+	"github.com/networkservicemesh/sdk/pkg/tools/prometheus"
 	"github.com/pkg/errors"
 
 	"github.com/networkservicemesh/sdk-vpp/pkg/tools/ifindex"
 )
 
+const serverPref string = "server_"
+
 // Save retrieved vpp interface metrics in pathSegment
 func retrieveMetrics(ctx context.Context, statsConn *core.StatsConnection, segment *networkservice.PathSegment, isClient bool) {
 	swIfIndex, ok := ifindex.Load(ctx, isClient)
@@ -49,7 +52,7 @@ func retrieveMetrics(ctx context.Context, statsConn *core.StatsConnection, segme
 		return
 	}
 
-	addName := "server_"
+	addName := serverPref
 	if isClient {
 		addName = "client_"
 	}
@@ -67,6 +70,23 @@ func retrieveMetrics(ctx context.Context, statsConn *core.StatsConnection, segme
 		segment.Metrics[addName+"rx_packets"] = strconv.FormatUint(iface.Rx.Packets, 10)
 		segment.Metrics[addName+"tx_packets"] = strconv.FormatUint(iface.Tx.Packets, 10)
 		segment.Metrics[addName+"drops"] = strconv.FormatUint(iface.Drops, 10)
+
+		if prometheus.IsEnabled() {
+			if addName == serverPref {
+				ServerRxBytes.Set(float64(iface.Rx.Bytes))
+				ServerTxBytes.Set(float64(iface.Tx.Bytes))
+				ServerRxPackets.Set(float64(iface.Rx.Packets))
+				ServerTxPackets.Set(float64(iface.Tx.Packets))
+				ServerDrops.Set(float64(iface.Drops))
+			} else {
+				ClientRxBytes.Set(float64(iface.Rx.Bytes))
+				ClientTxBytes.Set(float64(iface.Tx.Bytes))
+				ClientRxPackets.Set(float64(iface.Rx.Packets))
+				ClientTxPackets.Set(float64(iface.Tx.Packets))
+				ClientDrops.Set(float64(iface.Drops))
+			}
+		}
+
 		break
 	}
 }

pkg/networkservice/metrics/stats/prometheus.go

@@ -0,0 +1,114 @@
+// Copyright (c) 2024 Nordix Foundation.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at:
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package stats
+
+import (
+	"sync"
+
+	prom "github.com/networkservicemesh/sdk/pkg/tools/prometheus"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+var (
+	prometheusInitOnce sync.Once
+
+	// ClientRxBytes - Total received bytes by client
+	ClientRxBytes = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "client_rx_bytes_total",
+			Help: "Total received bytes by client",
+		},
+	)
+	// ClientTxBytes - Total transmitted bytes by client
+	ClientTxBytes = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "client_tx_bytes_total",
+			Help: "Total transmitted bytes by client",
+		},
+	)
+	// ClientRxPackets - Total received packets by client
+	ClientRxPackets = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "client_rx_packets_total",
+			Help: "Total received packets by client",
+		},
+	)
+	// ClientTxPackets - Total transmitted packets by client
+	ClientTxPackets = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "client_tx_packets_total",
+			Help: "Total transmitted packets by client",
+		},
+	)
+	// ClientDrops - Total drops by client
+	ClientDrops = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "client_drops_total",
+			Help: "Total drops by client",
+		},
+	)
+	// ServerRxBytes - Total received bytes by server
+	ServerRxBytes = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "server_rx_bytes_total",
+			Help: "Total received bytes by server",
+		},
+	)
+	// ServerTxBytes - Total transmitted bytes by server
+	ServerTxBytes = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "server_tx_bytes_total",
+			Help: "Total transmitted bytes by server",
+		},
+	)
+	// ServerRxPackets - Total received packets by server
+	ServerRxPackets = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "server_rx_packets_total",
+			Help: "Total received packets by server",
+		},
+	)
+	// ServerTxPackets - Total transmitted packets by server
+	ServerTxPackets = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "server_tx_packets_total",
+			Help: "Total transmitted packets by server",
+		},
+	)
+	// ServerDrops - Total drops by server
+	ServerDrops = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "server_drops_total",
+			Help: "Total drops by server",
+		},
+	)
+)
+
+func registerMetrics() {
+	if prom.IsEnabled() {
+		prometheus.MustRegister(ClientRxBytes)
+		prometheus.MustRegister(ClientTxBytes)
+		prometheus.MustRegister(ClientRxPackets)
+		prometheus.MustRegister(ClientTxPackets)
+		prometheus.MustRegister(ClientDrops)
+		prometheus.MustRegister(ServerRxBytes)
+		prometheus.MustRegister(ServerTxBytes)
+		prometheus.MustRegister(ServerRxPackets)
+		prometheus.MustRegister(ServerTxPackets)
+		prometheus.MustRegister(ServerDrops)
+	}
+}

pkg/networkservice/metrics/stats/server.go

@@ -42,6 +42,7 @@ type statsServer struct {
 
 // NewServer provides a NetworkServiceServer chain elements that retrieves vpp interface statistics.
 func NewServer(ctx context.Context, options ...Option) networkservice.NetworkServiceServer {
+	prometheusInitOnce.Do(registerMetrics)
 	opts := &statsOptions{}
 	for _, opt := range options {
 		opt(opts)