feat: Integrate Prometheus metrics for gRPC server and add metrics en…

…dpoint

go.mod

@@ -9,6 +9,7 @@ require (
 	github.com/ghodss/yaml v1.0.0
 	github.com/golang/protobuf v1.5.4
 	github.com/google/uuid v1.6.0
+	github.com/grpc-ecosystem/go-grpc-middleware/providers/prometheus v1.0.1
 	github.com/mattn/go-sqlite3 v1.14.23
 	github.com/pkg/errors v0.9.1
 	github.com/prometheus/client_golang v1.20.5
@@ -54,6 +55,7 @@ require (
 	github.com/goccy/go-json v0.10.3 // indirect
 	github.com/golang/snappy v0.0.4 // indirect
 	github.com/google/flatbuffers v24.3.25+incompatible // indirect
+	github.com/grpc-ecosystem/go-grpc-middleware/v2 v2.1.0 // indirect
 	github.com/hashicorp/go-secure-stdlib/parseutil v0.1.8 // indirect
 	github.com/hashicorp/go-secure-stdlib/strutil v0.1.2 // indirect
 	github.com/hashicorp/go-sockaddr v1.0.6 // indirect

go.sum

@@ -72,6 +72,10 @@ github.com/google/pprof v0.0.0-20230817174616-7a8ec2ada47b h1:h9U78+dx9a4BKdQkBB
 github.com/google/pprof v0.0.0-20230817174616-7a8ec2ada47b/go.mod h1:czg5+yv1E0ZGTi6S6vVK1mke0fV+FaUhNGcd6VRS9Ik=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/grpc-ecosystem/go-grpc-middleware/providers/prometheus v1.0.1 h1:qnpSQwGEnkcRpTqNOIR6bJbR0gAorgP9CSALpRcKoAA=
+github.com/grpc-ecosystem/go-grpc-middleware/providers/prometheus v1.0.1/go.mod h1:lXGCsh6c22WGtjr+qGHj1otzZpV/1kwTMAqkwZsnWRU=
+github.com/grpc-ecosystem/go-grpc-middleware/v2 v2.1.0 h1:pRhl55Yx1eC7BZ1N+BBWwnKaMyD8uC+34TLdndZMAKk=
+github.com/grpc-ecosystem/go-grpc-middleware/v2 v2.1.0/go.mod h1:XKMd7iuf/RGPSMJ/U4HP0zS2Z9Fh8Ps9a+6X26m/tmI=
 github.com/hashicorp/go-secure-stdlib/parseutil v0.1.8 h1:iBt4Ew4XEGLfh6/bPk4rSYmuZJGizr6/x/AEizP0CQc=
 github.com/hashicorp/go-secure-stdlib/parseutil v0.1.8/go.mod h1:aiJI+PIApBRQG7FZTEBx5GiiX+HbOHilUdNxUZi4eV0=
 github.com/hashicorp/go-secure-stdlib/strutil v0.1.2 h1:kes8mmyCpxJsI7FTwtzRqEy9CdjCtrXrXGuOpxEA7Ts=

go/main.go

@@ -4,6 +4,7 @@ import (
 	"flag"
 	"fmt"
 	"net"
+	"net/http"
 	"os"
 	"os/signal"
 	"strings"
@@ -14,13 +15,16 @@ import (
 	"github.com/feast-dev/feast/go/internal/feast/server"
 	"github.com/feast-dev/feast/go/internal/feast/server/logging"
 	"github.com/feast-dev/feast/go/protos/feast/serving"
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/rs/zerolog/log"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/health"
 	"google.golang.org/grpc/health/grpc_health_v1"
 
+	grpcPrometheus "github.com/grpc-ecosystem/go-grpc-middleware/providers/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 	_ "go.uber.org/automaxprocs"
-	grpctrace "gopkg.in/DataDog/dd-trace-go.v1/contrib/google.golang.org/grpc"
+	grpcTrace "gopkg.in/DataDog/dd-trace-go.v1/contrib/google.golang.org/grpc"
 	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
 )
 
@@ -127,11 +131,22 @@ func StartGrpcServer(fs *feast.FeatureStore, host string, port int, writeLoggedF
 		return err
 	}
 
-	grpcServer := grpc.NewServer(grpc.UnaryInterceptor(grpctrace.UnaryServerInterceptor()))
+	grpcPromMetrics := grpcPrometheus.NewServerMetrics()
+	prometheus.MustRegister(grpcPromMetrics)
+	grpcServer := grpc.NewServer(
+		grpc.ChainUnaryInterceptor(grpcTrace.UnaryServerInterceptor(), grpcPromMetrics.UnaryServerInterceptor()),
+	)
 	serving.RegisterServingServiceServer(grpcServer, ser)
 	healthService := health.NewServer()
 	grpc_health_v1.RegisterHealthServer(grpcServer, healthService)
 
+	// Running Prometheus metrics endpoint on a separate goroutine
+	go func() {
+		http.Handle("/metrics", promhttp.Handler())
+		log.Info().Msg("Starting metrics endpoint on port 8080")
+		log.Fatal().Stack().Err(http.ListenAndServe(":8080", nil))
+	}()
+
 	stop := make(chan os.Signal, 1)
 	signal.Notify(stop, syscall.SIGINT, syscall.SIGTERM)