code: def setup_container_system_config(basedir, mountdir=None):
      
      etc = os.path.join(basedir, b"etc")
      if not os.path.exists(etc):
          os.mkdir(etc)
  
      for file, content in CONTAINER_ETC_FILE_OVERRIDE.items():
          # Create "basedir/etc/file"
          util.write_file(content, etc, file)
          if mountdir:
              # Create bind mount to "mountdir/etc/file"
              make_bind_mount(
                  os.path.join(etc, file), os.path.join(mountdir, b"etc", file), private=True)
  
      os.symlink(b"/proc/self/mounts", os.path.join(etc, b"mtab"))
docs: Create a minimal system configuration for use in a container.
      @param basedir: The directory where the configuration files should be placed as bytes.
      @param mountdir: If present, bind mounts to the configuration files will be added below
          this path (given as bytes).