Support HTTP/2.0 (#7204)

Fixes #6704

cmd/rpc/client.go

@@ -29,6 +29,7 @@ import (
 
 	xhttp "github.com/minio/minio/cmd/http"
 	xnet "github.com/minio/minio/pkg/net"
+	"golang.org/x/net/http2"
 )
 
 // DefaultRPCTimeout - default RPC timeout is one minute.
@@ -36,8 +37,9 @@ const DefaultRPCTimeout = 1 * time.Minute
 
 // Client - http based RPC client.
 type Client struct {
-	httpClient *http.Client
-	serviceURL *xnet.URL
+	httpClient          *http.Client
+	httpIdleConnsCloser func()
+	serviceURL          *xnet.URL
 }
 
 // Call - calls service method on RPC server.
@@ -87,8 +89,11 @@ func (client *Client) Call(serviceMethod string, args, reply interface{}) error
 	return gobDecode(callResponse.ReplyBytes, reply)
 }
 
-// Close - does nothing and presents for interface compatibility.
+// Close closes all idle connections of the underlying http client
 func (client *Client) Close() error {
+	if client.httpIdleConnsCloser != nil {
+		client.httpIdleConnsCloser()
+	}
 	return nil
 }
 
@@ -110,23 +115,29 @@ func newCustomDialContext(timeout time.Duration) func(ctx context.Context, netwo
 }
 
 // NewClient - returns new RPC client.
-func NewClient(serviceURL *xnet.URL, tlsConfig *tls.Config, timeout time.Duration) *Client {
-	return &Client{
-		httpClient: &http.Client{
-			// Transport is exactly same as Go default in https://golang.org/pkg/net/http/#RoundTripper
-			// except custom DialContext and TLSClientConfig.
-			Transport: &http.Transport{
-				Proxy:                 http.ProxyFromEnvironment,
-				DialContext:           newCustomDialContext(timeout),
-				MaxIdleConnsPerHost:   4096,
-				MaxIdleConns:          4096,
-				IdleConnTimeout:       90 * time.Second,
-				TLSHandshakeTimeout:   10 * time.Second,
-				ExpectContinueTimeout: 1 * time.Second,
-				TLSClientConfig:       tlsConfig,
-				DisableCompression:    true,
-			},
-		},
-		serviceURL: serviceURL,
+func NewClient(serviceURL *xnet.URL, tlsConfig *tls.Config, timeout time.Duration) (*Client, error) {
+	// Transport is exactly same as Go default in https://golang.org/pkg/net/http/#RoundTripper
+	// except custom DialContext and TLSClientConfig.
+	tr := &http.Transport{
+		Proxy:                 http.ProxyFromEnvironment,
+		DialContext:           newCustomDialContext(timeout),
+		MaxIdleConnsPerHost:   4096,
+		MaxIdleConns:          4096,
+		IdleConnTimeout:       120 * time.Second,
+		TLSHandshakeTimeout:   30 * time.Second,
+		ExpectContinueTimeout: 10 * time.Second,
+		TLSClientConfig:       tlsConfig,
+		DisableCompression:    true,
 	}
+	if tlsConfig != nil {
+		// If TLS is enabled configure http2
+		if err := http2.ConfigureTransport(tr); err != nil {
+			return nil, err
+		}
+	}
+	return &Client{
+		httpClient:          &http.Client{Transport: tr},
+		httpIdleConnsCloser: tr.CloseIdleConnections,
+		serviceURL:          serviceURL,
+	}, nil
 }

cmd/rpc/client_test.go

@@ -39,7 +39,10 @@ func TestClientCall(t *testing.T) {
 	if err != nil {
 		t.Fatalf("unexpected error %v", err)
 	}
-	rpcClient := NewClient(url, nil, DefaultRPCTimeout)
+	rpcClient, err := NewClient(url, nil, DefaultRPCTimeout)
+	if err != nil {
+		t.Fatalf("NewClient initialization error %v", err)
+	}
 
 	var reply int
 	var boolReply bool