HDFS (Hadoop Distributed File System) implementation - #42

This includes an HDFS docker image to use with the integration tests.

Co-authored-by: Ivan Andreev <ivandeex@gmail.com>
Co-authored-by: Nick Craig-Wood <nick@craig-wood.com>

backend/hdfs/hdfs.go

@@ -0,0 +1,58 @@
+// +build !plan9
+
+package hdfs
+
+import (
+	"path"
+	"strings"
+
+	"github.com/rclone/rclone/fs"
+	"github.com/rclone/rclone/fs/config"
+	"github.com/rclone/rclone/lib/encoder"
+)
+
+func init() {
+	fsi := &fs.RegInfo{
+		Name:        "hdfs",
+		Description: "Hadoop distributed file system",
+		NewFs:       NewFs,
+		Options: []fs.Option{{
+			Name:     "namenode",
+			Help:     "hadoop name node and port",
+			Required: true,
+			Examples: []fs.OptionExample{{
+				Value: "namenode:8020",
+				Help:  "Connect to host namenode at port 8020",
+			}},
+		}, {
+			Name:     "username",
+			Help:     "hadoop user name",
+			Required: false,
+			Examples: []fs.OptionExample{{
+				Value: "root",
+				Help:  "Connect to hdfs as root",
+			}},
+		}, {
+			Name:     config.ConfigEncoding,
+			Help:     config.ConfigEncodingHelp,
+			Advanced: true,
+			Default:  (encoder.Display | encoder.EncodeInvalidUtf8 | encoder.EncodeColon),
+		}},
+	}
+	fs.Register(fsi)
+}
+
+// Options for this backend
+type Options struct {
+	Namenode string               `config:"namenode"`
+	Username string               `config:"username"`
+	Enc      encoder.MultiEncoder `config:"encoding"`
+}
+
+// xPath make correct file path with leading '/'
+func xPath(root string, tail string) string {
+	if !strings.HasPrefix(root, "/") {
+		root = "/" + root
+	}
+	return path.Join(root, tail)
+}