Support for setting custom Transport in S3Client configuration (#3510)

cmd/client-s3.go

@@ -137,6 +137,11 @@ func newFactory() func(config *Config) (Client, *probe.Error) {
 				creds = credentials.NewStaticV2(config.AccessKey, config.SecretKey, "")
 			}
 
+			var transport http.RoundTripper
+
+			if config.Transport != nil {
+				transport = config.Transport
+			} else {
 				tr := &http.Transport{
 					Proxy: http.ProxyFromEnvironment,
 					DialContext: (&net.Dialer{
@@ -155,7 +160,6 @@ func newFactory() func(config *Config) (Client, *probe.Error) {
 					//    https://golang.org/src/net/http/transport.go?h=roundTrip#L1843
 					DisableCompression: true,
 				}
-
 				if useTLS {
 					// Keep TLS config.
 					tlsConfig := &tls.Config{
@@ -179,8 +183,9 @@ func newFactory() func(config *Config) (Client, *probe.Error) {
 					// 	return nil, probe.NewError(e)
 					// }
 				}
+				transport = tr
+			}
 
-			var transport http.RoundTripper = tr
 			if config.Debug {
 				if strings.EqualFold(config.Signature, "S3v4") {
 					transport = httptracer.GetNewTraceTransport(newTraceV4(), transport)

cmd/client.go

@@ -19,6 +19,7 @@ package cmd
 import (
 	"context"
 	"io"
+	"net/http"
 	"os"
 	"time"
 
@@ -194,6 +195,7 @@ type Config struct {
 	Debug        bool
 	Insecure     bool
 	Lookup       minio.BucketLookupType
+	Transport    *http.Transport
 }
 
 // SelectObjectOpts - opts entered for select API