set http transport config for gateway (#4765)

This change sets the http config for the minio client used by the
minio server in gateway mode.

Fixes #4765

cmd/gateway-anonymous.go

@@ -16,7 +16,12 @@
 
 package cmd
 
-import "net/http"
+import (
+	"crypto/tls"
+	"net"
+	"net/http"
+	"time"
+)
 
 func anonErrToObjectErr(statusCode int, params ...string) error {
 	bucket := ""
@@ -47,3 +52,23 @@ func anonErrToObjectErr(statusCode int, params ...string) error {
 
 	return errUnexpected
 }
+
+// newCustomHTTPTransport returns a new http configuration
+// used while communicating with the cloud backends.
+// This sets the value for MaxIdleConns from 2 (go default) to
+// 100.
+func newCustomHTTPTransport() http.RoundTripper {
+	return &http.Transport{
+		Proxy: http.ProxyFromEnvironment,
+		DialContext: (&net.Dialer{
+			Timeout:   30 * time.Second,
+			KeepAlive: 30 * time.Second,
+		}).DialContext,
+		MaxIdleConns:          100,
+		IdleConnTimeout:       90 * time.Second,
+		TLSHandshakeTimeout:   10 * time.Second,
+		ExpectContinueTimeout: 1 * time.Second,
+		TLSClientConfig:       &tls.Config{RootCAs: globalRootCAs},
+		DisableCompression:    true,
+	}
+}