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moby--moby/volumes.go

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package docker
import (
"fmt"
"github.com/dotcloud/docker/archive"
"github.com/dotcloud/docker/pkg/mount"
"github.com/dotcloud/docker/utils"
"io/ioutil"
"log"
"os"
"path/filepath"
"strings"
"syscall"
)
type BindMap struct {
SrcPath string
DstPath string
Mode string
}
func prepareVolumesForContainer(container *Container) error {
if container.Volumes == nil || len(container.Volumes) == 0 {
container.Volumes = make(map[string]string)
container.VolumesRW = make(map[string]bool)
if err := applyVolumesFrom(container); err != nil {
return err
}
}
if err := createVolumes(container); err != nil {
return err
}
return nil
}
func mountVolumesForContainer(container *Container, envPath string) error {
// Setup the root fs as a bind mount of the base fs
var (
root = container.RootfsPath()
runtime = container.runtime
)
if err := os.MkdirAll(root, 0755); err != nil && !os.IsExist(err) {
return nil
}
// Create a bind mount of the base fs as a place where we can add mounts
// without affecting the ability to access the base fs
if err := mount.Mount(container.basefs, root, "none", "bind,rw"); err != nil {
return err
}
// Make sure the root fs is private so the mounts here don't propagate to basefs
if err := mount.ForceMount(root, root, "none", "private"); err != nil {
return err
}
// Mount docker specific files into the containers root fs
if err := mount.Mount(runtime.sysInitPath, filepath.Join(root, "/.dockerinit"), "none", "bind,ro"); err != nil {
return err
}
if err := mount.Mount(envPath, filepath.Join(root, "/.dockerenv"), "none", "bind,ro"); err != nil {
return err
}
if err := mount.Mount(container.ResolvConfPath, filepath.Join(root, "/etc/resolv.conf"), "none", "bind,ro"); err != nil {
return err
}
if container.HostnamePath != "" && container.HostsPath != "" {
if err := mount.Mount(container.HostnamePath, filepath.Join(root, "/etc/hostname"), "none", "bind,ro"); err != nil {
return err
}
if err := mount.Mount(container.HostsPath, filepath.Join(root, "/etc/hosts"), "none", "bind,ro"); err != nil {
return err
}
}
// Mount user specified volumes
for r, v := range container.Volumes {
mountAs := "ro"
if container.VolumesRW[r] {
mountAs = "rw"
}
r = filepath.Join(root, r)
if p, err := utils.FollowSymlinkInScope(r, root); err != nil {
return err
} else {
r = p
}
if err := mount.Mount(v, r, "none", fmt.Sprintf("bind,%s", mountAs)); err != nil {
return err
}
}
return nil
}
func unmountVolumesForContainer(container *Container) {
var (
root = container.RootfsPath()
mounts = []string{
root,
filepath.Join(root, "/.dockerinit"),
filepath.Join(root, "/.dockerenv"),
filepath.Join(root, "/etc/resolv.conf"),
}
)
if container.HostnamePath != "" && container.HostsPath != "" {
mounts = append(mounts, filepath.Join(root, "/etc/hostname"), filepath.Join(root, "/etc/hosts"))
}
for r := range container.Volumes {
mounts = append(mounts, filepath.Join(root, r))
}
for i := len(mounts) - 1; i >= 0; i-- {
if lastError := mount.Unmount(mounts[i]); lastError != nil {
log.Printf("Failed to umount %v: %v", mounts[i], lastError)
}
}
}
func applyVolumesFrom(container *Container) error {
if container.Config.VolumesFrom != "" {
for _, containerSpec := range strings.Split(container.Config.VolumesFrom, ",") {
var (
mountRW = true
specParts = strings.SplitN(containerSpec, ":", 2)
)
switch len(specParts) {
case 0:
return fmt.Errorf("Malformed volumes-from specification: %s", container.Config.VolumesFrom)
case 2:
switch specParts[1] {
case "ro":
mountRW = false
case "rw": // mountRW is already true
default:
return fmt.Errorf("Malformed volumes-from specification: %s", containerSpec)
}
}
c := container.runtime.Get(specParts[0])
if c == nil {
return fmt.Errorf("Container %s not found. Impossible to mount its volumes", container.ID)
}
for volPath, id := range c.Volumes {
if _, exists := container.Volumes[volPath]; exists {
continue
}
if err := os.MkdirAll(filepath.Join(container.basefs, volPath), 0755); err != nil {
return err
}
container.Volumes[volPath] = id
if isRW, exists := c.VolumesRW[volPath]; exists {
container.VolumesRW[volPath] = isRW && mountRW
}
}
}
}
return nil
}
func getBindMap(container *Container) (map[string]BindMap, error) {
var (
// Create the requested bind mounts
binds = make(map[string]BindMap)
// Define illegal container destinations
illegalDsts = []string{"/", "."}
)
for _, bind := range container.hostConfig.Binds {
// FIXME: factorize bind parsing in parseBind
var (
src, dst, mode string
arr = strings.Split(bind, ":")
)
if len(arr) == 2 {
src = arr[0]
dst = arr[1]
mode = "rw"
} else if len(arr) == 3 {
src = arr[0]
dst = arr[1]
mode = arr[2]
} else {
return nil, fmt.Errorf("Invalid bind specification: %s", bind)
}
// Bail if trying to mount to an illegal destination
for _, illegal := range illegalDsts {
if dst == illegal {
return nil, fmt.Errorf("Illegal bind destination: %s", dst)
}
}
bindMap := BindMap{
SrcPath: src,
DstPath: dst,
Mode: mode,
}
binds[filepath.Clean(dst)] = bindMap
}
return binds, nil
}
func createVolumes(container *Container) error {
binds, err := getBindMap(container)
if err != nil {
return err
}
volumesDriver := container.runtime.volumes.driver
// Create the requested volumes if they don't exist
for volPath := range container.Config.Volumes {
volPath = filepath.Clean(volPath)
volIsDir := true
// Skip existing volumes
if _, exists := container.Volumes[volPath]; exists {
continue
}
var srcPath string
var isBindMount bool
srcRW := false
// If an external bind is defined for this volume, use that as a source
if bindMap, exists := binds[volPath]; exists {
isBindMount = true
srcPath = bindMap.SrcPath
if strings.ToLower(bindMap.Mode) == "rw" {
srcRW = true
}
if stat, err := os.Stat(bindMap.SrcPath); err != nil {
return err
} else {
volIsDir = stat.IsDir()
}
// Otherwise create an directory in $ROOT/volumes/ and use that
} else {
// Do not pass a container as the parameter for the volume creation.
// The graph driver using the container's information ( Image ) to
// create the parent.
c, err := container.runtime.volumes.Create(nil, nil, "", "", nil)
if err != nil {
return err
}
srcPath, err = volumesDriver.Get(c.ID)
if err != nil {
return fmt.Errorf("Driver %s failed to get volume rootfs %s: %s", volumesDriver, c.ID, err)
}
srcRW = true // RW by default
}
if p, err := filepath.EvalSymlinks(srcPath); err != nil {
return err
} else {
srcPath = p
}
container.Volumes[volPath] = srcPath
container.VolumesRW[volPath] = srcRW
// Create the mountpoint
volPath = filepath.Join(container.basefs, volPath)
rootVolPath, err := utils.FollowSymlinkInScope(volPath, container.basefs)
if err != nil {
return err
}
if _, err := os.Stat(rootVolPath); err != nil {
if os.IsNotExist(err) {
if volIsDir {
if err := os.MkdirAll(rootVolPath, 0755); err != nil {
return err
}
} else {
if err := os.MkdirAll(filepath.Dir(rootVolPath), 0755); err != nil {
return err
}
if f, err := os.OpenFile(rootVolPath, os.O_CREATE, 0755); err != nil {
return err
} else {
f.Close()
}
}
}
}
// Do not copy or change permissions if we are mounting from the host
if srcRW && !isBindMount {
volList, err := ioutil.ReadDir(rootVolPath)
if err != nil {
return err
}
if len(volList) > 0 {
srcList, err := ioutil.ReadDir(srcPath)
if err != nil {
return err
}
if len(srcList) == 0 {
// If the source volume is empty copy files from the root into the volume
if err := archive.CopyWithTar(rootVolPath, srcPath); err != nil {
return err
}
var stat syscall.Stat_t
if err := syscall.Stat(rootVolPath, &stat); err != nil {
return err
}
var srcStat syscall.Stat_t
if err := syscall.Stat(srcPath, &srcStat); err != nil {
return err
}
// Change the source volume's ownership if it differs from the root
// files that were just copied
if stat.Uid != srcStat.Uid || stat.Gid != srcStat.Gid {
if err := os.Chown(srcPath, int(stat.Uid), int(stat.Gid)); err != nil {
return err
}
}
}
}
}
}
return nil
}