Add mount command for mounting machine directories

This comes in handy, when wanting to use volumes with drivers that
don't support folder sharing (such as KVM, as opposed to VirtualBox)

You will need FUSE and SSHFS installed, in order to use this feature.
The machine will also need a "sftp" binary, but most of them have it.

Signed-off-by: Anders F Björklund <[email protected]>
(cherry picked from commit 30de5bb)

Dockerfile

@@ -3,6 +3,8 @@ FROM golang:1.8.3
 RUN apt-get update && apt-get install -y --no-install-recommends \
                 openssh-client \
                 rsync \
+                fuse \
+                sshfs \
         && rm -rf /var/lib/apt/lists/*
 
 RUN go get  github.com/golang/lint/golint \

commands/commands.go

@@ -361,6 +361,18 @@ var Commands = []cli.Command{
 			},
 		},
 	},
+	{
+		Name:        "mount",
+		Usage:       "Mount or unmount a directory from a machine with SSHFS.",
+		Description: "Arguments are [machine:][path] [mountpoint]",
+		Action:      runCommand(cmdMount),
+		Flags: []cli.Flag{
+			cli.BoolFlag{
+				Name:  "unmount, u",
+				Usage: "Unmount instead of mount",
+			},
+		},
+	},
 	{
 		Name:        "start",
 		Usage:       "Start a machine",

commands/mount.go

@@ -0,0 +1,136 @@
+package commands
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+
+	"github.com/docker/machine/libmachine"
+	"github.com/docker/machine/libmachine/log"
+)
+
+var (
+	// TODO: possibly move this to ssh package
+	baseSSHFSArgs = []string{
+		"-o", "StrictHostKeyChecking=no",
+		"-o", "UserKnownHostsFile=/dev/null",
+		"-o", "LogLevel=quiet", // suppress "Warning: Permanently added '[localhost]:2022' (ECDSA) to the list of known hosts."
+	}
+)
+
+func cmdMount(c CommandLine, api libmachine.API) error {
+	args := c.Args()
+	if len(args) < 1 || len(args) > 2 {
+		c.ShowHelp()
+		return errWrongNumberArguments
+	}
+
+	src := args[0]
+	dest := ""
+	if len(args) > 1 {
+		dest = args[1]
+	}
+
+	hostInfoLoader := &storeHostInfoLoader{api}
+
+	cmd, err := getMountCmd(src, dest, c.Bool("unmount"), hostInfoLoader)
+	if err != nil {
+		return err
+	}
+
+	cmd.Stdin = os.Stdin
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+
+	return cmd.Run()
+}
+
+func getMountCmd(src, dest string, unmount bool, hostInfoLoader HostInfoLoader) (*exec.Cmd, error) {
+	var cmdPath string
+	var err error
+	if !unmount {
+		cmdPath, err = exec.LookPath("sshfs")
+		if err != nil {
+			return nil, errors.New("You must have a copy of the sshfs binary locally to use the mount feature")
+		}
+	} else {
+		cmdPath, err = exec.LookPath("fusermount")
+		if err != nil {
+			return nil, errors.New("You must have a copy of the fusermount binary locally to use the unmount option")
+		}
+	}
+
+	srcHost, srcUser, srcPath, srcOpts, err := getInfoForSshfsArg(src, hostInfoLoader)
+	if err != nil {
+		return nil, err
+	}
+
+	if dest == "" {
+		dest = srcPath
+	}
+
+	sshArgs := baseSSHFSArgs
+	if srcHost.GetSSHKeyPath() != "" {
+		sshArgs = append(sshArgs, "-o", "IdentitiesOnly=yes")
+	}
+
+	// Append needed -i / private key flags to command.
+	sshArgs = append(sshArgs, srcOpts...)
+
+	// Append actual arguments for the sshfs command (i.e. docker@<ip>:/path)
+	locationArg, err := generateLocationArg(srcHost, srcUser, srcPath)
+	if err != nil {
+		return nil, err
+	}
+
+	if !unmount {
+		sshArgs = append(sshArgs, locationArg)
+		sshArgs = append(sshArgs, dest)
+	} else {
+		sshArgs = []string{"-u"}
+		sshArgs = append(sshArgs, dest)
+	}
+
+	cmd := exec.Command(cmdPath, sshArgs...)
+	log.Debug(*cmd)
+	return cmd, nil
+}
+
+func getInfoForSshfsArg(hostAndPath string, hostInfoLoader HostInfoLoader) (h HostInfo, user string, path string, args []string, err error) {
+	// Path with hostname.  e.g. "hostname:/usr/bin/cmatrix"
+	var hostName string
+	if parts := strings.SplitN(hostAndPath, ":", 2); len(parts) < 2 {
+		hostName = defaultMachineName
+		path = parts[0]
+	} else {
+		hostName = parts[0]
+		path = parts[1]
+	}
+	if hParts := strings.SplitN(hostName, "@", 2); len(hParts) == 2 {
+		user, hostName = hParts[0], hParts[1]
+	}
+
+	// Remote path
+	h, err = hostInfoLoader.load(hostName)
+	if err != nil {
+		return nil, "", "", nil, fmt.Errorf("Error loading host: %s", err)
+	}
+
+	args = []string{}
+	port, err := h.GetSSHPort()
+	if err == nil && port > 0 {
+		args = append(args, "-o", fmt.Sprintf("Port=%v", port))
+	}
+
+	if h.GetSSHKeyPath() != "" {
+		args = append(args, "-o", fmt.Sprintf("IdentityFile=%s", h.GetSSHKeyPath()))
+	}
+
+	if user == "" {
+		user = h.GetSSHUsername()
+	}
+
+	return
+}

commands/mount_test.go

@@ -0,0 +1,84 @@
+package commands
+
+import (
+	"os/exec"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetMountCmd(t *testing.T) {
+	hostInfoLoader := MockHostInfoLoader{MockHostInfo{
+		ip:          "12.34.56.78",
+		sshPort:     234,
+		sshUsername: "root",
+		sshKeyPath:  "/fake/keypath/id_rsa",
+	}}
+
+	path, err := exec.LookPath("sshfs")
+	if err != nil {
+		t.Skip("sshfs not found (install sshfs ?)")
+	}
+	cmd, err := getMountCmd("myfunhost:/home/docker/foo", "/tmp/foo", false, &hostInfoLoader)
+
+	expectedArgs := append(
+		baseSSHFSArgs,
+		"-o",
+		"IdentitiesOnly=yes",
+		"-o",
+		"Port=234",
+		"-o",
+		"IdentityFile=/fake/keypath/id_rsa",
+		"[email protected]:/home/docker/foo",
+		"/tmp/foo",
+	)
+	expectedCmd := exec.Command(path, expectedArgs...)
+
+	assert.Equal(t, expectedCmd, cmd)
+	assert.NoError(t, err)
+}
+
+func TestGetMountCmdWithoutSshKey(t *testing.T) {
+	hostInfoLoader := MockHostInfoLoader{MockHostInfo{
+		ip:          "1.2.3.4",
+		sshUsername: "user",
+	}}
+
+	path, err := exec.LookPath("sshfs")
+	if err != nil {
+		t.Skip("sshfs not found (install sshfs ?)")
+	}
+	cmd, err := getMountCmd("myfunhost:/home/docker/foo", "", false, &hostInfoLoader)
+
+	expectedArgs := append(
+		baseSSHFSArgs,
+		"[email protected]:/home/docker/foo",
+		"/home/docker/foo",
+	)
+	expectedCmd := exec.Command(path, expectedArgs...)
+
+	assert.Equal(t, expectedCmd, cmd)
+	assert.NoError(t, err)
+}
+
+func TestGetMountCmdUnmount(t *testing.T) {
+	hostInfoLoader := MockHostInfoLoader{MockHostInfo{
+		ip:          "1.2.3.4",
+		sshUsername: "user",
+	}}
+
+	path, err := exec.LookPath("fusermount")
+	if err != nil {
+		t.Skip("fusermount not found (install fuse ?)")
+	}
+	cmd, err := getMountCmd("myfunhost:/home/docker/foo", "/tmp/foo", true, &hostInfoLoader)
+
+	expectedArgs := []string{
+		"-u",
+		"/tmp/foo",
+	}
+	expectedCmd := exec.Command(path, expectedArgs...)
+
+	assert.Equal(t, expectedCmd, cmd)
+	assert.NoError(t, err)
+}