Provided by: debos_1.1.1-2.1_amd64 
NAME
debos - Debian OS images builder
SYNOPSIS
debos [options] <recipe file in YAML>
debos [--help]
Application Options:
-b, --fakemachine-backend= Fakemachine backend to use (default: auto)
--artifactdir= Directory for packed archives and ostree repositories (default: current directory)
-t, --template-var= Template variables (use -t VARIABLE:VALUE syntax)
--debug-shell Fall into interactive shell on error
-s, --shell= Redefine interactive shell binary (default: bash) (default: /bin/bash)
--scratchsize= Size of disk backed scratch space
-c, --cpus= Number of CPUs to use for build VM (default: 2)
-m, --memory= Amount of memory for build VM (default: 2048MB)
--show-boot Show boot/console messages from the fake machine
-e, --environ-var= Environment variables (use -e VARIABLE:VALUE syntax)
-v, --verbose Verbose output
--print-recipe Print final recipe
--dry-run Compose final recipe to build but without any real work started
--disable-fakemachine Do not use fakemachine.
DESCRIPTION
debos is a tool to make the creation of various Debian-based OS images simpler. While
most other tools focus on specific use-cases, debos is more meant as a tool-chain to make
common actions trivial while providing enough rope to do whatever tweaking that might be
required behind the scene.
debos expects a YAML file as input and will run the actions listed in the file
sequentially. These actions should be self-contained and independent of each other.
Some of the actions provided by debos to customize and produce images are:
• apt: install packages and their dependencies with `apt'
• debootstrap: construct the target rootfs with debootstrap
• download: download a single file from the internet
• filesystem-deploy: deploy a root filesystem to an image previously created
• image-partition: create an image file, make partitions and format them
• ostree-commit: create an OSTree commit from rootfs
• ostree-deploy: deploy an OSTree branch to the image
• overlay: do a recursive copy of directories or files to the target filesystem
• pack: create a tarball with the target filesystem
• raw: directly write a file to the output image at a given offset
• recipe: includes the recipe actions at the given path
• run: allows to run a command or script in the filesystem or in the host
• unpack: unpack files from archive in the filesystem
A full syntax description of all the debos actions can be found at:
https://godoc.org/github.com/go-debos/debos/actions
INSTALLATION (DOCKER CONTAINER)
Official debos container is available:
docker pull godebos/debos
See docker/README.md (https://github.com/go-debos/debos/blob/master/docker/README.md) for
usage.
INSTALLATION (UNDER DEBIAN)
sudo apt install golang git libglib2.0-dev libostree-dev qemu-system-x86 \
qemu-user-static debootstrap systemd-container
export GOPATH=/opt/src/gocode # or whatever suits your needs
go install -v github.com/go-debos/debos/cmd/debos@latest
/opt/src/gocode/bin/debos --help
SIMPLE EXAMPLE
The following example will create a arm64 image, install several packages in it, change
the file /etc/hostname to “debian” and finally make a tarball.
{{- $image := or .image "debian.tgz" -}}
architecture: arm64
actions:
- action: debootstrap
suite: bookworm
components:
- main
- non-free-firmware
mirror: https://deb.debian.org/debian
variant: minbase
- action: apt
packages: [ sudo, openssh-server, adduser, systemd-sysv, firmware-linux ]
- action: run
chroot: true
command: echo debian > /etc/hostname
- action: pack
file: {{ $image }}
compression: gz
To run it, create a file named example.yaml and run:
debos example.yaml
The final tarball will be named “debian.tgz” if you would like to modify this name, you
can provided a different name for the variable image like this:
debos -t image:"debian-arm64.tgz" example.yaml
OTHER EXAMPLES
Example recipes are collected in a separate repository:
https://github.com/go-debos/debos-recipes
ENVIRONMENT VARIABLES
debos read a predefined list of environment variables from the host and propagates it to
fakemachine. The set of environment variables is defined by environ_vars on
cmd/debos/debos.go. Currently the list of environment variables includes the proxy
environment variables as documented at:
https://wiki.archlinux.org/index.php/proxy_settings
The list of environment variables currently exported to fakemachine is:
http_proxy, https_proxy, ftp_proxy, rsync_proxy, all_proxy, no_proxy
While the elements of environ_vars are in lower case, for each element both lower and
upper case variants are probed on the host, and if found propagated to fakemachine. So if
the host has the environment variables HTTP_PROXY and no_proxy defined, both will be
propagated to fakemachine respecting the case.
The command line options –environ-var and -e can be used to specify, overwrite, and unset
environment variables for fakemachine with the syntax:
$ debos -e ENVIRONVAR:VALUE ...
To unset an enviroment variable, or in other words, to prevent an environment variable to
be propagated to fakemachine, use the same syntax without a value. debos accept multiple
-e simultaneously.
PROXY CONFIGURATION
While the proxy related environment variables are exported from the host to fakemachine,
there are two known sources of issues:
• Using localhost will not work from fakemachine. Prefer using an address that is valid
on your network. debos will warn if environment variables contain localhost.
• In case you are running applications and/or scripts inside fakemachine you may need to
check which are the proxy environment variables they use. Different apps are known to
use different environment variable names and different case for environment variable
names.
FAKEMACHINE BACKEND
debos (unless running debos with the --disable-fakemachine argument) creates and spawns a
virtual machine using fakemachine (https://github.com/go-debos/fakemachine) and executes
the actions defined by the recipe inside the virtual machine. This helps ensure recipes
are reproducible no matter the host environment.
Fakemachine can use different virtualisation backends to spawn the virtualmachine, for
more information see the documentation under the fakemachine repository
(https://github.com/go-debos/fakemachine).
By default the backend will automatically be selected based on what is supported on the
host machine, but this can be overridden using the --fakemachine-backend / -b option. If
no backends are supported, debos reverts to running the recipe on the host without
creating a fakemachine.
Performance of the backends is roughly as follows: kvm is faster than uml is faster than
qemu. Using --disable-fakemachine is slightly faster than kvm, but requires root
permissions.
Numbers for running pine-a64-plus/debian.yaml (https://github.com/go-debos/debos-
recipes/blob/9a25b4be6c9136f4a27e542f39ab7e419fc852c9/pine-a64-plus/debian.yaml) on an
Intel Pentium G4560T with SSD:
Backend Wall Time Prerequisites
─────────────────────────────────────────────────────────────
--disable-fakemachine 8 min root permissions
-b kvm 9 min access to /dev/kvm
-b uml 18 min package user-mode-linux
installed
-b qemu 166 min none
debos(1)