package image import ( "context" "io" "os" "path/filepath" "github.com/docker/cli/cli" "github.com/docker/cli/cli/command" "github.com/pkg/errors" "github.com/spf13/cobra" ) type saveOptions struct { images []string output string } // NewSaveCommand creates a new `docker save` command func NewSaveCommand(dockerCli command.Cli) *cobra.Command { var opts saveOptions cmd := &cobra.Command{ Use: "save [OPTIONS] IMAGE [IMAGE...]", Short: "Save one or more images to a tar archive (streamed to STDOUT by default)", Args: cli.RequiresMinArgs(1), RunE: func(cmd *cobra.Command, args []string) error { opts.images = args return RunSave(dockerCli, opts) }, } flags := cmd.Flags() flags.StringVarP(&opts.output, "output", "o", "", "Write to a file, instead of STDOUT") return cmd } // RunSave performs a save against the engine based on the specified options func RunSave(dockerCli command.Cli, opts saveOptions) error { if opts.output == "" && dockerCli.Out().IsTerminal() { return errors.New("cowardly refusing to save to a terminal. Use the -o flag or redirect") } if err := validateOutputPath(opts.output); err != nil { return errors.Wrap(err, "failed to save image") } responseBody, err := dockerCli.Client().ImageSave(context.Background(), opts.images) if err != nil { return err } defer responseBody.Close() if opts.output == "" { _, err := io.Copy(dockerCli.Out(), responseBody) return err } return command.CopyToFile(opts.output, responseBody) } func validateOutputPath(path string) error { dir := filepath.Dir(path) if dir != "" && dir != "." { if _, err := os.Stat(dir); os.IsNotExist(err) { return errors.Errorf("unable to validate output path: directory %q does not exist", dir) } } return nil }