dwdeath / arkdep

Toolkit for building, deploying and maintaining an immutable, atomic, btrfs-based, multi-root system

Arkdep

Toolkit for building, deploying and maintaining an immutable, btrfs-based, multi-root system.

Arkdep attempts to be as simple to use as possible and avoid unnecessary abstraction, if you know how to use GNU/Linux picking up Arkdep should be painless for it maintains much of your old familiar workflow.

Warning

Arkdep is still in active development, no more breaking changes are planned since all core functionality is now in, however the current codebase has yet to be thoroughly tested, there may be lingering bugs or other issues

Usage

Rolling out Arkdep on a new system

Note

Arkdep has as of now only been tested on Arch Linux-based systems

Arkdep can be easily rolled out and torn down again, it is non-invasive by design. So it should be safe to just toy around with it on your system.

System requirements for usage;

• / is partitioned with btrfs
• /boot mounted boot partition
• 512MiB boot partition for max 2 deployments, 1GiB recommended
• Systemd-boot bootloader is installed and configured as the primary bootloader
• dracut, wget, curl and btrfs-progs are installed

System requirements for image building;

• arch-install-scripts and btrfs-progs are installed
• A btrfs partitioned workdir, default is /var/tmp

The following command will initialize Arkdep, it will deploy a subvolume containing all Arkdep related files excluding kernels and initramfs to /arkdep. Kernel and initramfs will instead be stored in /boot/arkdep upon generation.

sudo arkdep init

# Alternatively to init in to a specific directory
sudo arkdep init /target/dir

Once ardep is installed you should prepare the overlay located at /arkdep/overlay. The overlay is copied directly on to the root filesystem of a new deployment, create directories inside of it as-if it were a root filesystem. For example, /arkdep/overlay/etc will be your /etc folder.

You will most likely wish to add the following to the overlay;

• passwd, shadow, group, subgid and subuid files containing only entries for root and normal user accounts, system accounts will be supplied via the images and are stored separate in /usr/lib.
• fstab file with at least a writable /var subvolume configured
• Optionally a locale.conf/locale.gen, localtime symlink and custom dracut configuration

Here is a reference fstab file, take note of the subvol mount option;

UUID=f8b62c6c-fba0-41e5-b12c-42aa1cdaa452	/home       btrfs     	rw,relatime,discard=async,space_cache=v2,subvol=arkdep/shared/home,compress=zstd	0 0
UUID=f8b62c6c-fba0-41e5-b12c-42aa1cdaa452	/var        btrfs     	rw,relatime,discard=async,space_cache=v2,subvol=arkdep/shared/var,compress=zstd	0 0
UUID=f8b62c6c-fba0-41e5-b12c-42aa1cdaa452	/arkdep     btrfs     	rw,relatime,discard=async,space_cache=v2,subvol=arkdep,compress=zstd	0 0
UUID=1223-2137                              /boot       vfat      	rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=ascii,shortname=mixed,utf8,errors=remount-ro	0 2

If you wish to use custom kernel parameters you can edit /arkdep/templates/systemd-boot

Deploying an image

To deploy the latest available image from the default repository run the following command;

sudo arkdep deploy

It will check in with the server defined in /arkdep/config as repo_url and pull the latest image defined in $repo_url/$repo_default_image/database, see Repository for additional information.

Deploying a specified image version

A specific image version to pull and deploy can be parsed like so;

sudo arkdep deploy arkanelinux 00ce35074659538f946be77d9efaefc37725335689

The target name may be substituted with a - to pull the default target.

sudo arkdep deploy - 00ce35074659538f946be77d9efaefc37725335689

An item may be installed directly from the local /arkdep/cache directory, this will skip the database download and checksum check.

sudo arkdep deploy cache 00ce35074659538f946be77d9efaefc37725335689

You do not have to provide the full image name, you can provide it with an impartial image name, the first hit will be pulled and deployed.

sudo arkdep deploy arkanelinux 00ce

Packaging

Custom configurations

Arch Linux-based

arkdep-build.d
├── customlinux			# Directory carrying a custom name
|  ├── overlay			# (Optional) Root filesystem overlay directory, contents are copied to root
|  ├── boostrap.list		# Plain text file containing list of packages installed by pacstrap, used for installing the base system
|  ├── package.list		# (Optional) Plain text file containing list of packages installed by pacman in a chroot, used for aditional package installations
|  ├── type         		# Plain text file, for configs of the Arch type should contain `archlinux`
|  ├── extensions		# (Optional) Directory for custom scripts
|     ├── post-bootstrap.sh	# (Optional) Custom bash script which runs after bootstrapping the system
|     ├── post-install.sh	# (Optional) Custom bash script which runs after system installation is finished

Building an image

Note

If you are planning to spin custom images you will need to implement some type of mechanism for loading the /usr/lib account and group files, Arkane uses a patched libnss-extrausers PAM module to achieve this, Fedora Silverblue uses sssd

Use the arkdep-build script to build your customlinux images, currently the script is assuming to be run from inside of arkdep-build.d's parent directory.

sudo arkdep-build customlinux

# Or alternatively using a custom image name
sudo ARKDEP_CUSTOM_NAME='customlinux_v1.0' arkdep-build customlinux

Once done you can find compressed and uncompressed copies of your new image in the target directory.

Arkdep will by default generate a psuedo-random hex string and use this as the name of your image. This behaviour can be overwritten by assigning a custom name to the ARKDEP_CUSTOM_NAME environment variable.

Repository

Example repository layout

This would be a suitable layout if repo_url in /arkdep/config is set to https://repo.example.com/arkdep.

repo.example.com
├── arkdep
|  ├── list		                # Plain text file containing names of all available image types
|  ├── customlinux
|  |  ├── database		        # Plain text file containing : delimited lists of all available images `image_name:compression_method:sha1sum`
|  |  ├── customlinux_v1.0.tar.zst	# Compressed disk images
|  |  ├── customlinux_v1.0.tar.zst.sig	# Detached GPG signature
|  |  ├── customlinux_v2.0.tar.zst	# Compressed disk images
|  |  ├── customlinux_v2.0.tar.zst.sig	# Detached GPG signature
|  ├── customlinux-gnome
|  |  ├── database
|  |  ├── customlinux-gnome_v1.0.tar.zst
|  |  ├── customlinux-gnome_v2.0.tar.zst

Example repository configuration

The list file is in part optional, it not utilized during the deployment process but the user may use it in combination with the arkdep get-available command to request a list of all available images in the repository.

customlinux
customlinux-gnome
customlinux-kde

The database file contains a : delimited list of all available images. Each line contains the following information image_name:compression_method:sha1sum.

customlinux_v2.0:zst:d5f45b2dac77399b37231c6ec4e864d184d35cf1
customlinux_v1.0:zst:80ba4c7f3ff7a0ebce8e67d5b73f87c56af1b9f3

The image name is used to find the actual image, users can also manually refer to a version with arkdep deploy customlinux customlinux_v1.0

The compression method is flexible, any compression method tar can infer is supported. Some examples being xz, gz and zst.

The sha1sum is used to ensure the file was downloaded properly.

Arkdep will assume the top most entry in the database is the latest one, when no image version is defined or latest is requested it will grab the top most entry.

Signed images

A GPG signature is by default optional, if available Arkdep will use it instead of the sha1sum to verify image integrity. Arkdep can be configured to require these files to be provided by setting gpg_signature_check to 2 in the config file.

A keyring with trusted (private) keys is stored at /arkdep/keys/trusted-keys, keys are only accepted in binary format.

Arkdep assumes the signatures to be identical in name to their parent file with a .sig appended.

Generate a signature like so;

gpg --output customlinux_v1.0.tar.zst.sig --detach-sig customlinux_v1.0.tar.zst

Then simply drop these signatures next to disk image itself.