- `commit` (bool) - If true, the container will be committed to an image rather than exported. - `discard` (bool) - Throw away the container when the build is complete. This is useful for the [artifice post-processor](/docs/post-processors/artifice). - `export_path` (string) - The path where the final container will be exported as a tar file. - `image` (string) - The base image for the Docker container that will be started. This image will be pulled from the Docker registry if it doesn't already exist. - `message` (string) - Set a message for the commit.