minimize size

This plugin can be used to reduce the size of the resulting image. Often virtual volumes are much smaller than their reported size until any data is written to them. During the bootstrapping process temporary data like the aptitude cache is written to the volume only to be removed again.

The minimize size plugin employs various strategies to keep a low volume footprint:

  • Mount folders from the host into key locations of the image volume to avoid any unnecessary disk writes.
  • Use zerofree to deallocate unused sectors on the volume. On an unpartitioned volume this will be done for the entire volume, while it will only happen on the root partition for partitioned volumes.
  • Shrink the real volume size. Supported tools are:
  • Tell apt to only download specific language files. See the apt.conf manpage for more details (“Languages” in the “Acquire group” section).
  • Configure debootstrap and dpkg to filter out specific paths when installing packages


  • zerofree: Specifies if it should mark unallocated blocks as zeroes, so the volume could be better shrunk after this. Valid values: true, false Default: false optional

  • shrink: Whether the volume should be shrunk. This setting works best in conjunction with the zerofree tool. Valid values:

    • false: Do not shrink.
    • vmware-vdiskmanager or true: Shrink using the vmware-vdiskmanager utility.
    • qemu-img: Shrink using the qemu-img utility.

    Default: false optional

  • apt: Apt specific configurations. optional

    • autoclean: Configure apt to clean out the archive and cache after every run. Valid values: true, false Default: false optional
    • languages: List of languages apt should download. Use [none] to not download any languages at all. optional
    • gzip_indexes: Gzip apt package indexes. Valid values: true, false Default: false optional
    • autoremove_suggests: Suggested packages are removed when running. apt-get purge --auto-remove Valid values: true, false Default: false optional
  • dpkg: dpkg (and debootstrap) specific configurations. These settings not only affect the behavior of dpkg when installing packages after the image has been created, but also during the bootstrapping process. This includes the behavior of debootstrap. optional

    • locales: List of locales that should be kept. When this option is used, all locales (and the manpages in those locales) are excluded from installation excepting the ones in this list. Specify an empty list to not install any locales at all. optional
    • exclude_docs: Exclude additional package documentation located in /usr/share/doc Valid values: true, false Default: false optional