package container import ( "errors" "fmt" "io" "os" "path/filepath" "strings" "github.com/docker/docker/api/types" "github.com/docker/docker/cli" "github.com/docker/docker/cli/command" "github.com/docker/docker/pkg/archive" "github.com/docker/docker/pkg/system" "github.com/spf13/cobra" "golang.org/x/net/context" ) type copyOptions struct { source string destination string followLink bool } type copyDirection int const ( fromContainer copyDirection = (1 << iota) toContainer acrossContainers = fromContainer | toContainer ) type cpConfig struct { followLink bool } // NewCopyCommand creates a new `docker cp` command func NewCopyCommand(dockerCli *command.DockerCli) *cobra.Command { var opts copyOptions cmd := &cobra.Command{ Use: `cp [OPTIONS] CONTAINER:SRC_PATH DEST_PATH|- docker cp [OPTIONS] SRC_PATH|- CONTAINER:DEST_PATH`, Short: "Copy files/folders between a container and the local filesystem", Long: strings.Join([]string{ "Copy files/folders between a container and the local filesystem\n", "\nUse '-' as the source to read a tar archive from stdin\n", "and extract it to a directory destination in a container.\n", "Use '-' as the destination to stream a tar archive of a\n", "container source to stdout.", }, ""), Args: cli.ExactArgs(2), RunE: func(cmd *cobra.Command, args []string) error { if args[0] == "" { return errors.New("source can not be empty") } if args[1] == "" { return errors.New("destination can not be empty") } opts.source = args[0] opts.destination = args[1] return runCopy(dockerCli, opts) }, } flags := cmd.Flags() flags.BoolVarP(&opts.followLink, "follow-link", "L", false, "Always follow symbol link in SRC_PATH") return cmd } func runCopy(dockerCli *command.DockerCli, opts copyOptions) error { srcContainer, srcPath := splitCpArg(opts.source) dstContainer, dstPath := splitCpArg(opts.destination) var direction copyDirection if srcContainer != "" { direction |= fromContainer } if dstContainer != "" { direction |= toContainer } cpParam := &cpConfig{ followLink: opts.followLink, } ctx := context.Background() switch direction { case fromContainer: return copyFromContainer(ctx, dockerCli, srcContainer, srcPath, dstPath, cpParam) case toContainer: return copyToContainer(ctx, dockerCli, srcPath, dstContainer, dstPath, cpParam) case acrossContainers: // Copying between containers isn't supported. return errors.New("copying between containers is not supported") default: // User didn't specify any container. return errors.New("must specify at least one container source") } } func statContainerPath(ctx context.Context, dockerCli *command.DockerCli, containerName, path string) (types.ContainerPathStat, error) { return dockerCli.Client().ContainerStatPath(ctx, containerName, path) } func resolveLocalPath(localPath string) (absPath string, err error) { if absPath, err = filepath.Abs(localPath); err != nil { return } return archive.PreserveTrailingDotOrSeparator(absPath, localPath), nil } func copyFromContainer(ctx context.Context, dockerCli *command.DockerCli, srcContainer, srcPath, dstPath string, cpParam *cpConfig) (err error) { if dstPath != "-" { // Get an absolute destination path. dstPath, err = resolveLocalPath(dstPath) if err != nil { return err } } // if client requests to follow symbol link, then must decide target file to be copied var rebaseName string if cpParam.followLink { srcStat, err := statContainerPath(ctx, dockerCli, srcContainer, srcPath) // If the destination is a symbolic link, we should follow it. if err == nil && srcStat.Mode&os.ModeSymlink != 0 { linkTarget := srcStat.LinkTarget if !system.IsAbs(linkTarget) { // Join with the parent directory. srcParent, _ := archive.SplitPathDirEntry(srcPath) linkTarget = filepath.Join(srcParent, linkTarget) } linkTarget, rebaseName = archive.GetRebaseName(srcPath, linkTarget) srcPath = linkTarget } } content, stat, err := dockerCli.Client().CopyFromContainer(ctx, srcContainer, srcPath) if err != nil { return err } defer content.Close() if dstPath == "-" { // Send the response to STDOUT. _, err = io.Copy(os.Stdout, content) return err } // Prepare source copy info. srcInfo := archive.CopyInfo{ Path: srcPath, Exists: true, IsDir: stat.Mode.IsDir(), RebaseName: rebaseName, } preArchive := content if len(srcInfo.RebaseName) != 0 { _, srcBase := archive.SplitPathDirEntry(srcInfo.Path) preArchive = archive.RebaseArchiveEntries(content, srcBase, srcInfo.RebaseName) } // See comments in the implementation of `archive.CopyTo` for exactly what // goes into deciding how and whether the source archive needs to be // altered for the correct copy behavior. return archive.CopyTo(preArchive, srcInfo, dstPath) } func copyToContainer(ctx context.Context, dockerCli *command.DockerCli, srcPath, dstContainer, dstPath string, cpParam *cpConfig) (err error) { if srcPath != "-" { // Get an absolute source path. srcPath, err = resolveLocalPath(srcPath) if err != nil { return err } } // In order to get the copy behavior right, we need to know information // about both the source and destination. The API is a simple tar // archive/extract API but we can use the stat info header about the // destination to be more informed about exactly what the destination is. // Prepare destination copy info by stat-ing the container path. dstInfo := archive.CopyInfo{Path: dstPath} dstStat, err := statContainerPath(ctx, dockerCli, dstContainer, dstPath) // If the destination is a symbolic link, we should evaluate it. if err == nil && dstStat.Mode&os.ModeSymlink != 0 { linkTarget := dstStat.LinkTarget if !system.IsAbs(linkTarget) { // Join with the parent directory. dstParent, _ := archive.SplitPathDirEntry(dstPath) linkTarget = filepath.Join(dstParent, linkTarget) } dstInfo.Path = linkTarget dstStat, err = statContainerPath(ctx, dockerCli, dstContainer, linkTarget) } // Ignore any error and assume that the parent directory of the destination // path exists, in which case the copy may still succeed. If there is any // type of conflict (e.g., non-directory overwriting an existing directory // or vice versa) the extraction will fail. If the destination simply did // not exist, but the parent directory does, the extraction will still // succeed. if err == nil { dstInfo.Exists, dstInfo.IsDir = true, dstStat.Mode.IsDir() } var ( content io.Reader resolvedDstPath string ) if srcPath == "-" { // Use STDIN. content = os.Stdin resolvedDstPath = dstInfo.Path if !dstInfo.IsDir { return fmt.Errorf("destination \"%s:%s\" must be a directory", dstContainer, dstPath) } } else { // Prepare source copy info. srcInfo, err := archive.CopyInfoSourcePath(srcPath, cpParam.followLink) if err != nil { return err } srcArchive, err := archive.TarResource(srcInfo) if err != nil { return err } defer srcArchive.Close() // With the stat info about the local source as well as the // destination, we have enough information to know whether we need to // alter the archive that we upload so that when the server extracts // it to the specified directory in the container we get the desired // copy behavior. // See comments in the implementation of `archive.PrepareArchiveCopy` // for exactly what goes into deciding how and whether the source // archive needs to be altered for the correct copy behavior when it is // extracted. This function also infers from the source and destination // info which directory to extract to, which may be the parent of the // destination that the user specified. dstDir, preparedArchive, err := archive.PrepareArchiveCopy(srcArchive, srcInfo, dstInfo) if err != nil { return err } defer preparedArchive.Close() resolvedDstPath = dstDir content = preparedArchive } options := types.CopyToContainerOptions{ AllowOverwriteDirWithFile: false, } return dockerCli.Client().CopyToContainer(ctx, dstContainer, resolvedDstPath, content, options) } // We use `:` as a delimiter between CONTAINER and PATH, but `:` could also be // in a valid LOCALPATH, like `file:name.txt`. We can resolve this ambiguity by // requiring a LOCALPATH with a `:` to be made explicit with a relative or // absolute path: // `/path/to/file:name.txt` or `./file:name.txt` // // This is apparently how `scp` handles this as well: // http://www.cyberciti.biz/faq/rsync-scp-file-name-with-colon-punctuation-in-it/ // // We can't simply check for a filepath separator because container names may // have a separator, e.g., "host0/cname1" if container is in a Docker cluster, // so we have to check for a `/` or `.` prefix. Also, in the case of a Windows // client, a `:` could be part of an absolute Windows path, in which case it // is immediately proceeded by a backslash. func splitCpArg(arg string) (container, path string) { if system.IsAbs(arg) { // Explicit local absolute path, e.g., `C:\foo` or `/foo`. return "", arg } parts := strings.SplitN(arg, ":", 2) if len(parts) == 1 || strings.HasPrefix(parts[0], ".") { // Either there's no `:` in the arg // OR it's an explicit local relative path like `./file:name.txt`. return "", arg } return parts[0], parts[1] }