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package main
import (
"io"
"os"
"fmt"
"github.com/containers/storage"
"github.com/containers/storage/pkg/archive"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
"github.com/urfave/cli"
)
type exportOptions struct {
output string
container string
}
var (
exportFlags = []cli.Flag{
cli.StringFlag{
Name: "output, o",
Usage: "Write to a file, default is STDOUT",
Value: "/dev/stdout",
},
}
exportDescription = "Exports container's filesystem contents as a tar archive" +
" and saves it on the local machine."
exportCommand = cli.Command{
Name: "export",
Usage: "Export container's filesystem contents as a tar archive",
Description: exportDescription,
Flags: exportFlags,
Action: exportCmd,
ArgsUsage: "CONTAINER",
}
)
// exportCmd saves a container to a tarball on disk
func exportCmd(c *cli.Context) error {
args := c.Args()
if len(args) == 0 {
return errors.Errorf("container id must be specified")
}
if len(args) > 1 {
return errors.Errorf("too many arguments given, need 1 at most.")
}
container := args[0]
if err := validateFlags(c, exportFlags); err != nil {
return err
}
config, err := getConfig(c)
if err != nil {
return errors.Wrapf(err, "could not get config")
}
store, err := getStore(config)
if err != nil {
return err
}
output := c.String("output")
if output == "/dev/stdout" {
file := os.Stdout
if logrus.IsTerminal(file) {
return errors.Errorf("refusing to export to terminal. Use -o flag or redirect")
}
}
opts := exportOptions{
output: output,
container: container,
}
return exportContainer(store, opts)
}
// exportContainer exports the contents of a container and saves it as
// a tarball on disk
func exportContainer(store storage.Store, opts exportOptions) error {
mountPoint, err := store.Mount(opts.container, "")
if err != nil {
return errors.Wrapf(err, "error finding container %q", opts.container)
}
defer func() {
if err := store.Unmount(opts.container); err != nil {
fmt.Printf("error unmounting container %q: %v\n", opts.container, err)
}
}()
input, err := archive.Tar(mountPoint, archive.Uncompressed)
if err != nil {
return errors.Wrapf(err, "error reading container directory %q", opts.container)
}
outFile, err := os.Create(opts.output)
if err != nil {
return errors.Wrapf(err, "error creating file %q", opts.output)
}
defer outFile.Close()
_, err = io.Copy(outFile, input)
return err
}
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