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container export: implement file-write with atomicwriter

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Same functionality, but implemented with atomicwriter. There's a slight
difference in error-messages produced (but can be adjusted if we want).

Before:

    docker container export -o ./no/such/foo mycontainer
    failed to export container: invalid output path: directory "no/such" does not exist

    docker container export -o /no/permissions mycontainer
    failed to export container: stat /no/permissions: permission denied

After:

    docker container export -o ./no/such/foo mycontainer
    failed to export container: invalid file path: stat no/such: no such file or directory

    docker container export -o /no/permissions mycontainer
    failed to export container: failed to stat output path: lstat /no/permissions: permission denied

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
This commit is contained in:
Sebastiaan van Stijn 2025-03-09 21:25:44 +01:00
parent d47d2338b7
commit b8bcf6f5ad
No known key found for this signature in database
GPG Key ID: 76698F39D527CE8C
2 changed files with 20 additions and 20 deletions
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34
cli/command/container/export.go
View File

@ -7,6 +7,7 @@ import (
"github.com/docker/cli/cli"
"github.com/docker/cli/cli/command"
"github.com/docker/cli/cli/command/completion"
"github.com/moby/sys/atomicwriter"
"github.com/pkg/errors"
"github.com/spf13/cobra"
)
@ -41,27 +42,28 @@ func NewExportCommand(dockerCli command.Cli) *cobra.Command {
return cmd
}
func runExport(ctx context.Context, dockerCli command.Cli, opts exportOptions) error {
if opts.output == "" && dockerCli.Out().IsTerminal() {
return errors.New("cowardly refusing to save to a terminal. Use the -o flag or redirect")
func runExport(ctx context.Context, dockerCLI command.Cli, opts exportOptions) error {
var output io.Writer
if opts.output == "" {
if dockerCLI.Out().IsTerminal() {
return errors.New("cowardly refusing to save to a terminal. Use the -o flag or redirect")
}
output = dockerCLI.Out()
} else {
writer, err := atomicwriter.New(opts.output, 0o600)
if err != nil {
return errors.Wrap(err, "failed to export container")
}
defer writer.Close()
output = writer
}
if err := command.ValidateOutputPath(opts.output); err != nil {
return errors.Wrap(err, "failed to export container")
}
clnt := dockerCli.Client()
responseBody, err := clnt.ContainerExport(ctx, opts.container)
responseBody, err := dockerCLI.Client().ContainerExport(ctx, opts.container)
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)
_, err = io.Copy(output, responseBody)
return err
}

6
cli/command/container/export_test.go
View File

@ -42,8 +42,6 @@ func TestContainerExportOutputToIrregularFile(t *testing.T) {
cmd.SetErr(io.Discard)
cmd.SetArgs([]string{"-o", "/dev/random", "container"})
err := cmd.Execute()
assert.Assert(t, err != nil)
expected := `"/dev/random" must be a directory or a regular file`
assert.ErrorContains(t, err, expected)
const expected = `failed to export container: cannot write to a character device file`
assert.Error(t, cmd.Execute(), expected)
}