Move remote disk StorageAPI abstraction from RPC to REST (#6464)

cmd/rest/client.go

@@ -0,0 +1,108 @@
+/*
+ * Minio Cloud Storage, (C) 2018 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package rest
+
+import (
+	"context"
+	"crypto/tls"
+	"errors"
+	"io"
+	"io/ioutil"
+	"net"
+	"net/http"
+	"net/url"
+	"time"
+
+	xhttp "github.com/minio/minio/cmd/http"
+)
+
+// DefaultRESTTimeout - default RPC timeout is one minute.
+const DefaultRESTTimeout = 1 * time.Minute
+
+// Client - http based RPC client.
+type Client struct {
+	httpClient   *http.Client
+	url          *url.URL
+	newAuthToken func() string
+}
+
+// Call - make a REST call.
+func (c *Client) Call(method string, values url.Values, body io.Reader) (reply io.ReadCloser, err error) {
+	req, err := http.NewRequest(http.MethodPost, c.url.String()+"/"+method+"?"+values.Encode(), body)
+	if err != nil {
+		return nil, err
+	}
+
+	req.Header.Set("Authorization", "Bearer "+c.newAuthToken())
+	req.Header.Set("X-Minio-Time", time.Now().UTC().Format(time.RFC3339))
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		// Limit the ReadAll(), just in case, because of a bug, the server responds with large data.
+		r := io.LimitReader(resp.Body, 1024)
+		b, err := ioutil.ReadAll(r)
+		if err != nil {
+			return nil, err
+		}
+		return nil, errors.New(string(b))
+	}
+	return resp.Body, nil
+}
+
+func newCustomDialContext(timeout time.Duration) func(ctx context.Context, network, addr string) (net.Conn, error) {
+	return func(ctx context.Context, network, addr string) (net.Conn, error) {
+		dialer := &net.Dialer{
+			Timeout:   timeout,
+			KeepAlive: timeout,
+			DualStack: true,
+		}
+
+		conn, err := dialer.DialContext(ctx, network, addr)
+		if err != nil {
+			return nil, err
+		}
+
+		return xhttp.NewTimeoutConn(conn, timeout, timeout), nil
+	}
+}
+
+// NewClient - returns new RPC client.
+func NewClient(url *url.URL, tlsConfig *tls.Config, timeout time.Duration, newAuthToken func() string) *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,
+			},
+		},
+		url:          url,
+		newAuthToken: newAuthToken,
+	}
+}