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build-openstack-debian-image(1) General Commands Manual build-openstack-debian-image(1)


build-openstack-debian-image - build a Debian image to be used with OpenStack


build-openstack-debian-image --release|-r <wheezy|jessie|stretch|buster|bullseye> [ OPTIONS ]


The build-openstack-debian-image shell script will build a Debian image which can be used in an OpenStack IaaS cloud. The resulting (Qcow2 and raw images) contains initramfs-growroot so that the root partition will be resized (during the initramfs phase, before mouting anything) to match the flavor selected when using "nova boot". Later on during the boot process, cloud-init will resize the root partition on the fly (resize is performed when the partition is already mounted read-write, since recent kernel allow that for ext3).

Cloud-init is setup to use an Ec2 metadata server, which is what OpenStack is compatible with. A "debian" (configurable with the use of the --login option) user will be used to receive the ssh key from the user data blob. This user is setup without a password (eg: adduser --disabled-password). Once logged as this "debian" user in your new virtual machine, you can "sudo" to root from that user, without needing a password. The root password is "password" by default, and ssh into the root user without using an ssh keypair is disabled by default (PermitRootLogin without-password is set in /etc/ssh/sshd_config).


--release|-r wheezy|jessie|stretch|buster|bullseye

Sets the release name to be installed. Currently only 5 values a possible: wheezy or jessie or stretch or buster or bullseye.

At the time of writing, bullseye is only here to prepare the future, and will not work until it effectively becomes the new testing.


--extra-packages|-e PACKAGE,PACKAGE,...

Select the PACKAGE you want to add to the image default is: bash-completion,joe,most,screen,less,vim,bzip2 Note that this list of extra packages isn't used if you use the --minimal option.

--debootstrap-url|-u <debootstrap-debian-mirror>

Select the URL of the Debian mirror to use to perform the debootstrap. For example:

--boot-manager|-bm <grub|syslinux>

Select what type of boot manager to use inside the image. The default is Grub, but you can as well decide to use syslinux if you prefer.

--boot-type|-bt <mbr|uefi>

Select how to boot the image: using legacy MBR-style (aka BIOS or CSM) boot, or UEFI. The default is mbr. Selecting uefi requires the use of Grub as the boot manager, and will set up an extra EFI System Partition inside the image to support UEFI boot.

--architecture|- <amd64|arm64>

Select the architecture to target for the output image. This will not cross build for that architecture, but will pick the right architecture-specific components. Supported options are "amd64" and "arm64"; "amd64" is default.

--sources.list-mirror|-s <source-list-mirror>

URL to use when building the sources.list inside the chroot. If this option is omitted, then the global redirector is used. For example, you can use:


Without this option, the following packages will also be installed: bash-completion (and /etc/bash.bashrc will be setup to use bash-completion), joe (the text editor), most, GNU screen, less and vim. If you believe that more things should be added in the non-minimal image, suggestions are welcome.


Build an image for the Microsoft Azure cloud. Note that this option is incompatible with the --automatic-resize|-ar option, which will be ignored.

--image-size|-is <image-size>

Select the image size (default to 2 GBytes if this option is omitted). Only useful if you need to use a custom script hook (see below).


Reduce the image to the minimum HDD size possible. The partition of the image will be first shrinked with resize2fs -M, then the space it takes will be used to do a 2nd resize2fs adding a bit of extra space for the operating system to write runtime data (see below). Since this option takes a lot of time, it is disabled by default.

--automatic-resize-space|-ars <supplementary-space>

Size of the supplementary space added to the partition after it is resized to the minimum. If this option is omitted, then 50G is used. If --automatic-resize isn't used, then it is useless to set this option, which will be ignored.

--login|-l <user-login>

Change the login name (default to debian) for the user created by Cloud-Init.

--password|-p <root-password>

Defines a default root password for your image. This option is dangerous, first because it will show the root password to the user of the computer building the image if using "ps", then also because it is best to not set a default root password at all if possible. However, this option is still there, because sometimes, you need to be able to debug your image, and login through the web console of horizon. In a production environment, do not use this option.

--hook-script|-hs <hook-script>

If you wish to further customize the generated cloud image, you can use a hook script. When called, build-openstack-debian-image will fill up some BODI_* environment variable for the hook script to use as per below:

BODI_CHROOT_PATH path where the image is mounted

BODI_RELEASE name of the Debian release that is being bootstraped


Here is an example with the short parameter names:

build-openstack-debian-image -u -s -is 5 -e libapache2-mod-php5 -hs ~/customize-my-image -ar -ars 100

And the same but with long names for options:

build-openstack-debian-image --debootstrap-url --sources.list-mirror --image-size 5 --extra-packages libapache2-mod-php5 --hook-script ~/customize-my-image --automatic-resize --automatic-resize-space 100


build-openstack-debian-image has been written by Thomas Goirand <>, with contributions from Mehdi Abaakouk <>.