copyFromContainer method
Downloads sourceInContainer from the container and writes it to
destinationOnHost as a raw tar file.
Throws ContainerStartException when called before start.
Implementation
Future<void> copyFromContainer(
String sourceInContainer,
String destinationOnHost,
) async {
final tarData = await _dockerClient.archive(
_requireContainerId,
sourceInContainer,
);
final destFile = File(destinationOnHost);
await destFile.writeAsBytes(tarData);
}