pkg/compose: implement Export using atomicwriter

Replaces the use of cli/command.CopyToFile with an atomicwriter,
as cli/command.CopyToFile will be deprecated in the next release.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Author: thaJeztah

go.mod

@@ -30,6 +30,7 @@ require (
 	github.com/mitchellh/mapstructure v1.5.0
 	github.com/moby/buildkit v0.20.1
 	github.com/moby/patternmatcher v0.6.0
+	github.com/moby/sys/atomicwriter v0.1.0
 	github.com/moby/term v0.5.2
 	github.com/morikuni/aec v1.0.0
 	github.com/opencontainers/go-digest v1.0.0

go.sum

@@ -330,6 +330,8 @@ github.com/moby/patternmatcher v0.6.0 h1:GmP9lR19aU5GqSSFko+5pRqHi+Ohk1O69aFiKkV
 github.com/moby/patternmatcher v0.6.0/go.mod h1:hDPoyOpDY7OrrMDLaYoY3hf52gNCR/YOUYxkhApJIxc=
 github.com/moby/spdystream v0.4.0 h1:Vy79D6mHeJJjiPdFEL2yku1kl0chZpJfZcPpb16BRl8=
 github.com/moby/spdystream v0.4.0/go.mod h1:xBAYlnt/ay+11ShkdFKNAG7LsyK/tmNBVvVOwrfMgdI=
+github.com/moby/sys/atomicwriter v0.1.0 h1:kw5D/EqkBwsBFi0ss9v1VG3wIkVhzGvLklJ+w3A14Sw=
+github.com/moby/sys/atomicwriter v0.1.0/go.mod h1:Ul8oqv2ZMNHOceF643P6FKPXeCmYtlQMvpizfsSoaWs=
 github.com/moby/sys/capability v0.4.0 h1:4D4mI6KlNtWMCM1Z/K0i7RV1FkX+DBDHKVJpCndZoHk=
 github.com/moby/sys/capability v0.4.0/go.mod h1:4g9IK291rVkms3LKCDOoYlnV8xKwoDTpIrNEE35Wq0I=
 github.com/moby/sys/mountinfo v0.7.2 h1:1shs6aH5s4o5H2zQLn796ADW1wMrIwHsyJ2v9KouLrg=

pkg/compose/export.go

@@ -25,6 +25,7 @@ import (
 	"github.com/docker/cli/cli/command"
 	"github.com/docker/compose/v2/pkg/api"
 	"github.com/docker/compose/v2/pkg/progress"
+	"github.com/moby/sys/atomicwriter"
 )
 
 func (s *composeService) Export(ctx context.Context, projectName string, options api.ExportOptions) error {
@@ -41,11 +42,11 @@ func (s *composeService) export(ctx context.Context, projectName string, options
 		return err
 	}
 
-	if options.Output == "" && s.dockerCli.Out().IsTerminal() {
-		return fmt.Errorf("output option is required when exporting to terminal")
-	}
-
-	if err := command.ValidateOutputPath(options.Output); err != nil {
+	if options.Output == "" {
+		if s.dockerCli.Out().IsTerminal() {
+			return fmt.Errorf("output option is required when exporting to terminal")
+		}
+	} else if err := command.ValidateOutputPath(options.Output); err != nil {
 		return fmt.Errorf("failed to export container: %w", err)
 	}
 
@@ -83,9 +84,14 @@ func (s *composeService) export(ctx context.Context, projectName string, options
 		if options.Output == "" {
 			_, err := io.Copy(s.dockerCli.Out(), responseBody)
 			return err
-		}
-
-		if err := command.CopyToFile(options.Output, responseBody); err != nil {
+		} else {
+			writer, err := atomicwriter.New(options.Output, 0o600)
+			if err != nil {
+				return err
+			}
+			defer func() { _ = writer.Close() }()
+
+			_, err = io.Copy(writer, responseBody)
 			return err
 		}
 	}