devmapper: Add simple tool to test the DeviceSet commands

devmapper/docker-device-tool/device_tool.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"fmt"
+	"github.com/dotcloud/docker/devmapper"
+	"os"
+)
+
+func usage() {
+	fmt.Printf("Usage: %s [snap new-id base-id] | [remove id] | [mount id mountpoint]\n", os.Args[0])
+	os.Exit(1)
+}
+
+func main() {
+	devices := devmapper.NewDeviceSetDM("/var/lib/docker")
+
+	if len(os.Args) < 2 {
+		usage()
+	}
+
+	cmd := os.Args[1]
+	if cmd == "snap" {
+		if len(os.Args) < 4 {
+			usage()
+		}
+
+		err := devices.AddDevice(os.Args[2], os.Args[3])
+		if err != nil {
+			fmt.Println("Can't create snap device: ", err)
+			os.Exit(1)
+		}
+	} else if cmd == "remove" {
+		if len(os.Args) < 3 {
+			usage()
+		}
+
+		err := devices.RemoveDevice(os.Args[2])
+		if err != nil {
+			fmt.Println("Can't remove device: ", err)
+			os.Exit(1)
+		}
+	} else if cmd == "mount" {
+		if len(os.Args) < 4 {
+			usage()
+		}
+
+		err := devices.MountDevice(os.Args[2], os.Args[3])
+		if err != nil {
+			fmt.Println("Can't create snap device: ", err)
+			os.Exit(1)
+		}
+	} else {
+		fmt.Printf("Unknown command %s\n", cmd)
+		if len(os.Args) < 4 {
+			usage()
+		}
+
+		os.Exit(1)
+	}
+
+	return
+}