Client side metrics

config/BUILD.bazel

@@ -21,8 +21,10 @@ go_library(
         "//cache/s3proxy:go_default_library",
         "@com_github_azure_azure_sdk_for_go_sdk_azcore//:go_default_library",
         "@com_github_azure_azure_sdk_for_go_sdk_azidentity//:go_default_library",
+        "@com_github_grpc_ecosystem_go_grpc_prometheus//:go_default_library",
         "@com_github_minio_minio_go_v7//:go_default_library",
         "@com_github_minio_minio_go_v7//pkg/credentials:go_default_library",
+        "@com_github_prometheus_client_golang//prometheus:go_default_library",
         "@com_github_urfave_cli_v2//:go_default_library",
         "@in_gopkg_yaml_v3//:go_default_library",
         "@org_golang_google_grpc//:go_default_library",

config/proxy.go

@@ -15,6 +15,9 @@ import (
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/credentials/insecure"
+
+	grpc_prometheus "github.com/grpc-ecosystem/go-grpc-prometheus"
+	prom "github.com/prometheus/client_golang/prometheus"
 )
 
 func (c *Config) setProxy() error {
@@ -49,6 +52,15 @@ func (c *Config) setProxy() error {
 		} else {
 			opts = append(opts, grpc.WithTransportCredentials(insecure.NewCredentials()))
 		}
+		metrics := grpc_prometheus.NewClientMetrics(func(o *prom.CounterOpts) { o.Namespace = "proxy" })
+		metrics.EnableClientHandlingTimeHistogram(func(o *prom.HistogramOpts) { o.Namespace = "proxy" })
+		err := prom.Register(metrics)
+		if err != nil {
+			return err
+		}
+		opts = append(opts, grpc.WithChainStreamInterceptor(metrics.StreamClientInterceptor()))
+		opts = append(opts, grpc.WithChainUnaryInterceptor(metrics.UnaryClientInterceptor()))
+
 		conn, err := grpc.Dial(c.GRPCBackend.BaseUrl, opts...)
 		if err != nil {
 			return err