DOKK / manpages / debian 11 / bdebstrap / bdebstrap.1.en
BDEBSTRAP(1) bdebstrap’s Manual BDEBSTRAP(1)

bdebstrap - YAML config based multi-mirror Debian chroot creation tool

bdebstrap [-h|--help] [-c|--config CONFIG] [-n|--name NAME] [-e|--env ENV] [-s|--simulate|--dry-run] [-b|--output-base-dir OUTPUT_BASE_DIR] [-o|--output OUTPUT] [-q|--quiet|--silent|-v|--verbose|--debug] [-f|--force] [-t|--tmpdir TMPDIR] [--variant {extract,custom,essential,apt,required,minbase,buildd,important,debootstrap,-,standard}] [--mode {auto,sudo,root,unshare,fakeroot,fakechroot,proot,chrootless}] [--aptopt APTOPT] [--keyring KEYRING] [--dpkgopt DPKGOPT] [--hostname HOSTNAME] [--install-recommends] [--packages|--include PACKAGES] [--components COMPONENTS] [--architectures ARCHITECTURES] [--setup-hook COMMAND] [--essential-hook COMMAND] [--customize-hook COMMAND] [--cleanup-hook COMMAND] [--suite SUITE] [--target TARGET] [--mirrors MIRRORS] [SUITE [TARGET [MIRROR...]]]

bdebstrap creates a Debian chroot of SUITE into TARGET from one or more MIRRORs and places meta-data in the OUTPUT directory: A config.yaml containing the configuration for the build (useful for rebuilds) and a manifest listing all installed packages and versions. If TARGET is just a filename (and not include the path), it will be placed in the OUTPUT directory as well. bdebstrap extents mmdebtrap to make it configurable via YAML configuration files for more complex builds.

The configuration parameters can be passed to bdebstrap as command line arguments or in one or more configuration YAML files. The content of YAML files will be merged by appending lists and recursively merging maps. Arguments specified on the command line will take precedence over values provided in the YAML configuration file. The final merged parameters will be stored in the output directory as config.yaml.

Show a help message and exit
Configuration YAML file. See YAML CONFIGURATION below for the expected structure of this file. This parameter can be specified multiple times. The content of YAML files will be merged by appending lists and recursively merging maps.
name of the generated golden image. If no output directory is specified, the golden image will be placed in OUTPUT_BASE_DIR/NAME.
Add an additional environment variable. These environment variable will be set when calling the hooks.
Run apt-get with --simulate. Only the package cache is initialized but no binary packages are downloaded or installed. Use this option to quickly check whether a package selection within a certain suite and variant can in principle be installed as far as their dependencies go. If the output is a tarball, then no output is produced. If the output is a directory, then the directory will be left populated with the skeleton files and directories necessary for apt to run in it.
output base directory. By default it is the current directory.
output directory (default: output-base-dir/name)
Do not write anything to standard error except errors. If used together with --verbose or --debug, only the last option will take effect.
Write informational messages (about configuration files, environment variables, mmdebstrap call, etc.) to standard error. Instead of progress bars, mmdebstrap writes the dpkg and apt output directly to standard error. If used together with --quiet or --debug, only the last option will take effect.
In addition to the output produced by --verbose, write detailed debugging information to standard error. Errors of mmdebstrap will print a backtrace. If used together with --quiet or --verbose, only the last option will take effect.
Remove existing output directory before creating a new one
Temporary directory for building the image (default: /tmp)
Choose which package set to install.
Choose how to perform the chroot operation and create a filesystem with ownership information different from the current user.
Pass arbitrary options or configuration files to apt.
Change the default keyring to use by apt.
Pass arbitrary options or configuration files to dpkg.
Write the given HOSTNAME into /etc/hostname in the target chroot.
Consider recommended packages as a dependency for installing.
Comma or whitespace separated list of packages which will be installed in addition to the packages installed by the specified variant.
Comma or whitespace separated list of components like main, contrib and non-free which will be used for all URI-only MIRROR arguments.
Comma or whitespace separated list of architectures. The first architecture is the native architecture inside the chroot.
Execute arbitrary COMMAND right after initial setup (directory creation, configuration of apt and dpkg, ...) but before any packages are downloaded or installed. At that point, the chroot directory does not contain any executables and thus cannot be chroot-ed into. This option can be specified multiple times.
Execute arbitrary COMMAND after the Essential:yes packages have been installed, but before installing the remaining packages. This option can be specified multiple times.
Execute arbitrary COMMAND after the chroot is set up and all packages got installed but before final cleanup actions are carried out. This option can be specified multiple times.
Execute arbitrary COMMAND after all customize hooks have been executed. This option can be specified multiple times.
The suite may be a valid release code name (eg, sid, stretch, jessie) or a symbolic name (eg, unstable, testing, stable, oldstable).
The optional target argument can either be the path to a directory, the path to a tarball filename, the path to a squashfs image or -.
Comma separated list of mirrors. If no mirror option is provided, http://deb.debian.org/debian is used.

This section describes the expected data-structure hierarchy of the YAML configuration file(s). The top-level structure is expected to be a mapping. The top-level mapping may contain following keys:

mapping of environment variables names to their values. Environment variables can be overridden by specifying them with --env using the same name. These environment variable are set before calling the hooks.

String. Name of the generated golden image. Can be overridden by --name.

mapping. The values here are passed to mmdebstrap(1). Following keys might be specified:

list of arbitrary options or configuration files (string) to apt. Additional apt options can be specified with --aptopt.
list of architectures (string). The first architecture is the native architecture inside the chroot. Additional architectures can be specified with --architectures.
list of components (string) like main, contrib and non-free which will be used for all URI-only MIRROR arguments. Additional components can be specified with --components.
list of arbitrary options or configuration files (string) to dpkg. Additional dpkg options can be specified with --dpkgopt.
String. If specified, write the given hostname into /etc/hostname in the target chroot. This parameter does not exist in mmdebstrap and is implemented as customize hook for mmdebstrap. Can be overridden by --hostname.
Boolean. If set to True, the APT option Apt::Install-Recommends “true” is passed to mmdebstrap via --aptopt. Can be overridden by --install-recommends.
list of default keyring to use by apt. Additional keyring files can be specified with --keyring.
list of mirrors (string). Additional mirrors can be specified with --mirrors.
Choose how to perform the chroot operation and create a filesystem with ownership information different from the current user. It needs to be one of auto, sudo, root, unshare, fakeroot, fakechroot, proot, or chrootless. See mmdebstrap(1) for details. Can be overridden by --mode.
list of packages (string) which will be installed in addition to the packages installed by the specified variant. Additional packages can be specified with --packages or --include. This setting is passed to mmdebstrap using the --include parameter.
list of setup hooks (string). Execute arbitrary commands right after initial setup (directory creation, configuration of apt and dpkg, ...) but before any packages are downloaded or installed. At that point, the chroot directory does not contain any executables and thus cannot be chroot-ed into. See HOOKS in mmdebstrap(1) for more information and examples. Additional setup hooks can be specified with --setup-hook.
list of essential hooks (string). Execute arbitrary commands after the Essential:yes packages have been installed, but before installing the remaining packages. See HOOKS in mmdebstrap(1) for more information and examples. Additional essential hooks can be specified with --essential-hook.
list of customize hooks (string). Execute arbitrary commands after the chroot is set up and all packages got installed but before final cleanup actions are carried out. See HOOKS in mmdebstrap(1) for more information and examples. Additional customize hooks can be specified with --customize-hook.
list of cleanup hooks (string). Cleanup hooks are just hooks that are run directly after all other customize hooks. See customize-hooks above. Additional cleanup hooks can be specified with --cleanup-hook.
String. The suite may be a valid release code name (eg, sid, stretch, jessie) or a symbolic name (eg, unstable, testing, stable, oldstable). Can be overridden by --suite.
String. The target argument can either be the path to a directory, the path to a tarball filename, the path to a squashfs image or -. Can be overridden by --target.
Choose which package set to install. It needs to be one of extract, custom, essential, apt, required, minbase, buildd, important, debootstrap, -, standard. See mmdebstrap(1) for details. Can be overridden by --variant.

bdebstrap enhances the hooks provided by mmdebstrap. Hooks can use the environment variables specified via the env configuration option or the --env parameter. bdebstrap sets following environment variables by default to be consumed by the hooks:

name of the generated golden image which is set via the name configuration option of the --name parameter.
Path of a temporary directory inside the chroot. Files and directories that are placed inside this directory will be copied out of the image into the output directory. This temporary directory will be removed in a final cleanup hook.

This example shows how to use a small YAML configuration to build a minimal Debian unstable tarball. Assume following configuration is stored in unstable.yaml:

mmdebstrap:


  keyrings:


  - /usr/share/keyrings/debian-archive-keyring.gpg


  mode: unshare


  suite: unstable


  target: root.tar.xz


  variant: minbase

Then the tarball can be generated by running

$ bdebstrap -c unstable.yaml --name example1
$ ls example1/
config.yaml  manifest  root.tar.xz

This example shows how to use a YAML configuration to build a Debian 11 (bullseye) live system. Assume following configuration is stored in live.yaml:

mmdebstrap:


  architectures:


  - amd64


  cleanup-hooks:


  - cp /dev/null "$1/etc/hostname"


  - if test -f "$1/etc/resolv.conf"; then cp /dev/null "$1/etc/resolv.conf"; fi


  customize-hooks:


  - cp --preserve=timestamps -v "$1"/boot/vmlinu* "$1${BDEBSTRAP_OUTPUT_DIR?}/vmlinuz"


  - cp --preserve=timestamps -v "$1"/boot/initrd.img* "$1${BDEBSTRAP_OUTPUT_DIR?}/initrd.img"


  - mkdir -p "$1/root/.ssh"


  - upload ~/.ssh/id_rsa.pub /root/.ssh/authorized_keys


  keyrings:


  - /usr/share/keyrings/debian-archive-keyring.gpg


  mode: unshare


  packages:


  - init


  - iproute2


  - less


  - libpam-systemd


  - linux-image-cloud-amd64


  - live-boot


  - locales


  - openssh-server


  suite: bullseye


  target: root.squashfs


  variant: minbase

This example assumes that ~/.ssh/id_rsa.pub exists, because it will be copied into the image to /root/.ssh/authorized_keys to allow SSH access using the user’s SSH key.

The squashfs image can be generated by running

$ bdebstrap -c live.yaml --name example2
$ ls example2/
config.yaml  initrd.img  manifest  root.squashfs  vmlinuz

The kernel and initrd are copied out of the squashfs image using customize hooks to allow them to be used directly by QEMU. To launch this image locally with QEMU, the root.squashfs image needs to be provided by a HTTP server:

$ python3 -m http.server -b localhost --directory example2 8080

This command exposes the generated image via HTTP on localhost on port 8080. QEMU can be started passing the TCP traffic on port 8080 to the webserver:

$ cd example2
$ qemu-system-x86_64 -machine accel=kvm -m 1G -device virtio-net-pci,netdev=net0 -monitor vc \


    -netdev user,id=net0,hostfwd=tcp::2222-:22,guestfwd=tcp:10.0.2.252:8080-tcp:localhost:8080,hostname=debian-live \


    -kernel ./vmlinuz -initrd ./initrd.img -append "boot=live fetch=http://10.0.2.252:8080/root.squashfs quiet"

To print the output on the launching terminal, add -nographic -serial stdio to the QEMU command line and console=ttyS0 to the -append parameter. Once the virtual machine is started, it can be accessed via SSH:

$ ssh -oUserKnownHostsFile=/dev/null -oStrictHostKeyChecking=no -p 2222 root@localhost

mmdebstrap(1), debootstrap(8)

Benjamin Drung <bdrung@posteo.de>

2020-05-26 bdebstrap