Merge pull request #495 from rhatdan/tmpfs

Add support for Premount and Postmount commands.

configs/mount.go

@@ -18,4 +18,17 @@ type Mount struct {
 
 	// Relabel source if set, "z" indicates shared, "Z" indicates unshared.
 	Relabel string `json:"relabel"`
+
+	// Optional Command to be run before Source is mounted.
+	PremountCmds []Command `json:"premount_cmds"`
+
+	// Optional Command to be run after Source is mounted.
+	PostmountCmds []Command `json:"postmount_cmds"`
+}
+
+type Command struct {
+	Path string   `json:"path"`
+	Args []string `json:"args"`
+	Env  []string `json:"env"`
+	Dir  string   `json:"dir"`
 }

integration/exec_test.go

@@ -4,8 +4,10 @@ import (
 	"bytes"
 	"io/ioutil"
 	"os"
+	"path/filepath"
 	"strconv"
 	"strings"
+	"syscall"
 	"testing"
 
 	"github.com/docker/libcontainer"
@@ -645,3 +647,76 @@ func TestPassExtraFiles(t *testing.T) {
 		t.Fatalf("expected second pipe to receive '2', got '%s'", out2)
 	}
 }
+
+func TestMountCmds(t *testing.T) {
+	if testing.Short() {
+		return
+	}
+	root, err := newTestRoot()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(root)
+
+	rootfs, err := newRootfs()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer remove(rootfs)
+
+	tmpDir, err := ioutil.TempDir("", "tmpdir")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	config := newTemplateConfig(rootfs)
+	config.Mounts = append(config.Mounts, &configs.Mount{
+		Source:      tmpDir,
+		Destination: filepath.Join(rootfs, "tmp"),
+		Device:      "bind",
+		Flags:       syscall.MS_BIND | syscall.MS_REC,
+		PremountCmds: []configs.Command{
+			{Path: "touch", Args: []string{filepath.Join(tmpDir, "hello")}},
+			{Path: "touch", Args: []string{filepath.Join(tmpDir, "world")}},
+		},
+		PostmountCmds: []configs.Command{
+			{Path: "cp", Args: []string{filepath.Join(rootfs, "tmp", "hello"), filepath.Join(rootfs, "tmp", "hello-backup")}},
+			{Path: "cp", Args: []string{filepath.Join(rootfs, "tmp", "world"), filepath.Join(rootfs, "tmp", "world-backup")}},
+		},
+	})
+
+	factory, err := libcontainer.New(root, libcontainer.Cgroupfs)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	container, err := factory.Create("test", config)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer container.Destroy()
+
+	pconfig := libcontainer.Process{
+		Args: []string{"sh", "-c", "env"},
+		Env:  standardEnvironment,
+	}
+	err = container.Start(&pconfig)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Wait for process
+	waitProcess(&pconfig, t)
+
+	entries, err := ioutil.ReadDir(tmpDir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected := []string{"hello", "hello-backup", "world", "world-backup"}
+	for i, e := range entries {
+		if e.Name() != expected[i] {
+			t.Errorf("Got(%s), expect %s", e.Name(), expected[i])
+		}
+	}
+}

rootfs_linux.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"strings"
 	"syscall"
@@ -24,9 +25,20 @@ func setupRootfs(config *configs.Config, console *linuxConsole) (err error) {
 		return newSystemError(err)
 	}
 	for _, m := range config.Mounts {
+		for _, precmd := range m.PremountCmds {
+			if err := mountCmd(precmd); err != nil {
+				return newSystemError(err)
+			}
+		}
 		if err := mountToRootfs(m, config.Rootfs, config.MountLabel); err != nil {
 			return newSystemError(err)
 		}
+
+		for _, postcmd := range m.PostmountCmds {
+			if err := mountCmd(postcmd); err != nil {
+				return newSystemError(err)
+			}
+		}
 	}
 	if err := createDevices(config); err != nil {
 		return newSystemError(err)
@@ -62,6 +74,18 @@ func setupRootfs(config *configs.Config, console *linuxConsole) (err error) {
 	return nil
 }
 
+func mountCmd(cmd configs.Command) error {
+
+	command := exec.Command(cmd.Path, cmd.Args[:]...)
+	command.Env = cmd.Env
+	command.Dir = cmd.Dir
+	if out, err := command.CombinedOutput(); err != nil {
+		return fmt.Errorf("%#v failed: %s: %v", cmd, string(out), err)
+	}
+
+	return nil
+}
+
 func mountToRootfs(m *configs.Mount, rootfs, mountLabel string) error {
 	var (
 		dest = m.Destination