Add support for metrics api

Author: mpignatelli12

api/metrics/connecthandler/metrics_connect.go

@@ -0,0 +1,70 @@
+// Copyright (C) 2019-2024, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package connecthandler
+
+import (
+	"context"
+
+	"connectrpc.com/connect"
+	"github.com/prometheus/client_golang/prometheus"
+
+	metricsv1 "github.com/ava-labs/avalanchego/proto/pb/metrics/v1"
+	dto "github.com/prometheus/client_model/go"
+)
+
+type ConnectMetricsService struct {
+	Service prometheus.Gatherer
+}
+
+func NewConnectMetricsService(service prometheus.Gatherer) *ConnectMetricsService {
+	return &ConnectMetricsService{
+		Service: service,
+	}
+}
+
+func (s *ConnectMetricsService) GetMetrics(_ context.Context, _ *connect.Request[metricsv1.MetricsRequest]) (
+	*connect.Response[metricsv1.MetricsReply], error) {
+	mfs, err := s.Service.Gather()
+	if err != nil {
+		return nil, connect.NewError(connect.CodeInternal, err)
+	}
+
+	var metricsProtoList []*metricsv1.Metric
+
+	for _, mf := range mfs {
+		for _, m := range mf.Metric {
+			labels := make(map[string]string, len(m.Label))
+			for _, label := range m.Label {
+				labels[label.GetName()] = label.GetValue()
+			}
+
+			var value float64
+			switch mf.GetType() {
+			case dto.MetricType_COUNTER:
+				if m.Counter != nil {
+					value = m.Counter.GetValue()
+				}
+			case dto.MetricType_GAUGE:
+				if m.Gauge != nil {
+					value = m.Gauge.GetValue()
+				}
+			default:
+				// Skip histograms, summaries, and untyped metrics
+				continue
+			}
+
+			metricsProtoList = append(metricsProtoList, &metricsv1.Metric{
+				Name:   mf.GetName(),
+				Type:   mf.GetType().String(),
+				Help:   mf.GetHelp(),
+				Value:  value,
+				Labels: labels,
+			})
+		}
+	}
+
+	return connect.NewResponse(&metricsv1.MetricsReply{
+		Metrics: metricsProtoList,
+	}), nil
+}

node/node.go

@@ -51,6 +51,7 @@ import (
 	"github.com/ava-labs/avalanchego/proto/pb/admin/v1/adminv1connect"
 	"github.com/ava-labs/avalanchego/proto/pb/health/v1/healthv1connect"
 	"github.com/ava-labs/avalanchego/proto/pb/info/v1/infov1connect"
+	"github.com/ava-labs/avalanchego/proto/pb/metrics/v1/metricsv1connect"
 	"github.com/ava-labs/avalanchego/snow"
 	"github.com/ava-labs/avalanchego/snow/networking/benchlist"
 	"github.com/ava-labs/avalanchego/snow/networking/router"
@@ -85,6 +86,7 @@ import (
 	adminconnect "github.com/ava-labs/avalanchego/api/admin/connecthandler"
 	healthconnect "github.com/ava-labs/avalanchego/api/health/connecthandler"
 	infoconnect "github.com/ava-labs/avalanchego/api/info/connecthandler"
+	metricsconnect "github.com/ava-labs/avalanchego/api/metrics/connecthandler"
 	databasefactory "github.com/ava-labs/avalanchego/database/factory"
 	avmconfig "github.com/ava-labs/avalanchego/vms/avm/config"
 	platformconfig "github.com/ava-labs/avalanchego/vms/platformvm/config"
@@ -792,7 +794,7 @@ func (n *Node) initDatabase() error {
 	rawExpectedGenesisHash := hashing.ComputeHash256(n.Config.GenesisBytes)
 
 	rawGenesisHash, err := n.DB.Get(genesisHashKey)
-	if err == database.ErrNotFound {
+	if errors.Is(err, database.ErrNotFound) {
 		rawGenesisHash = rawExpectedGenesisHash
 		err = n.DB.Put(genesisHashKey, rawGenesisHash)
 	}
@@ -1285,6 +1287,20 @@ func (n *Node) initMetricsAPI() error {
 
 	n.Log.Info("initializing metrics API")
 
+	metricsServicePattern, metricsServiceHandler := metricsv1connect.NewMetricsServiceHandler(
+		metricsconnect.NewConnectMetricsService(n.MetricsGatherer),
+	)
+
+	reflectionPattern, reflectionHandler := grpcreflect.NewHandlerV1(
+		grpcreflect.NewStaticReflector(metricsv1connect.MetricsServiceName),
+	)
+
+	mux := http.NewServeMux()
+	mux.Handle(reflectionPattern, reflectionHandler)
+	mux.Handle(metricsServicePattern, metricsServiceHandler)
+
+	n.APIServer.AddHeaderRoute("metrics", mux)
+
 	return n.APIServer.AddRoute(
 		promhttp.HandlerFor(
 			n.MetricsGatherer,

proto/metrics/v1/service.proto

@@ -0,0 +1,22 @@
+syntax = "proto3";
+package metrics.v1;
+
+option go_package = "github.com/ava-labs/avalanchego/proto/pb/metrics/v1;metricsv1";
+
+service MetricsService {
+  rpc GetMetrics (MetricsRequest) returns (MetricsReply);
+}
+
+message MetricsRequest {}
+
+message MetricsReply {
+  repeated Metric metrics = 1;
+}
+
+message Metric {
+  string name = 1;
+  string type = 2;
+  string help = 3;
+  double value = 4;
+  map<string, string> labels = 5;
+}