github.com/AliyunContainerService/cli@v0.0.0-20181009023821-814ced4b30d0/cli/command/image/save.go (about)

     1  package image
     2  
     3  import (
     4  	"context"
     5  	"io"
     6  	"os"
     7  	"path/filepath"
     8  
     9  	"github.com/docker/cli/cli"
    10  	"github.com/docker/cli/cli/command"
    11  	"github.com/pkg/errors"
    12  	"github.com/spf13/cobra"
    13  )
    14  
    15  type saveOptions struct {
    16  	images []string
    17  	output string
    18  }
    19  
    20  // NewSaveCommand creates a new `docker save` command
    21  func NewSaveCommand(dockerCli command.Cli) *cobra.Command {
    22  	var opts saveOptions
    23  
    24  	cmd := &cobra.Command{
    25  		Use:   "save [OPTIONS] IMAGE [IMAGE...]",
    26  		Short: "Save one or more images to a tar archive (streamed to STDOUT by default)",
    27  		Args:  cli.RequiresMinArgs(1),
    28  		RunE: func(cmd *cobra.Command, args []string) error {
    29  			opts.images = args
    30  			return RunSave(dockerCli, opts)
    31  		},
    32  	}
    33  
    34  	flags := cmd.Flags()
    35  
    36  	flags.StringVarP(&opts.output, "output", "o", "", "Write to a file, instead of STDOUT")
    37  
    38  	return cmd
    39  }
    40  
    41  // RunSave performs a save against the engine based on the specified options
    42  func RunSave(dockerCli command.Cli, opts saveOptions) error {
    43  	if opts.output == "" && dockerCli.Out().IsTerminal() {
    44  		return errors.New("cowardly refusing to save to a terminal. Use the -o flag or redirect")
    45  	}
    46  
    47  	if err := validateOutputPath(opts.output); err != nil {
    48  		return errors.Wrap(err, "failed to save image")
    49  	}
    50  
    51  	responseBody, err := dockerCli.Client().ImageSave(context.Background(), opts.images)
    52  	if err != nil {
    53  		return err
    54  	}
    55  	defer responseBody.Close()
    56  
    57  	if opts.output == "" {
    58  		_, err := io.Copy(dockerCli.Out(), responseBody)
    59  		return err
    60  	}
    61  
    62  	return command.CopyToFile(opts.output, responseBody)
    63  }
    64  
    65  func validateOutputPath(path string) error {
    66  	dir := filepath.Dir(path)
    67  	if dir != "" && dir != "." {
    68  		if _, err := os.Stat(dir); os.IsNotExist(err) {
    69  			return errors.Errorf("unable to validate output path: directory %q does not exist", dir)
    70  		}
    71  	}
    72  	return nil
    73  }