ALMA - Arch Linux Mobile Appliance

Note: This project is no longer maintained, and some people have reported that it made their host system unbootable. Use at your own risk.

Almost every live Linux distribution out there is meant for a specific purpose, whether it's data rescue, privacy, penetration testing or anything else. There are some more generic distributions but all of them are based on squashfs, meaning that changes don't persist reboots.

ALMA is meant for those who wish to have a mutable live environment. It installs Arch Linux into a USB or an SD card, almost as if it was a hard drive. Some configuration is applied in order to minimize writes to the USB and making sure the system is bootable on both BIOS and UEFI systems.

Upgrading your packages is as easy as running pacman -Syu (or Topgrade) while the system is booted. This tool also provides an easy chroot command, so you can keep your live environment up to date without having to boot it. Encrypting the root partition is as easy as providing the -e flag

Installation

You can either build the project using cargo build or install the alma package from AUR.

Using Arch Linux derivatives

Using Arch Linux derivatives, such as Manjaro, isn't supported it ALMA. It may work and may not. Please do not open bugs or feature requests if you are not using the official Arch Linux.

Usage

Image creation on removable device

sudo alma create /dev/disk/by-id/usb-Generic_USB_Flash_Disk-0:0

This will wipe the entire disk and create a bootable installation of Arch Linux. You can use either removable devices or loop devices. As a precaution, ALMA will not wipe non-removable devices.

Not specifying any path will cause ALMA to interactively prompt the user for a removable device.

Disk encryption

You can enable disk encryption with the -e flag:

sudo alma create -e  /dev/disk/by-id/usb-Generic_USB_Flash_Disk-0:0

You will be prompted to enter and confirm the encryption passphrase during image creation.

chroot

After the installation is done you can either boot from it immediately or use arch-chroot to perform further customizations before your first boot (e.g. installing wireless device drivers).

You can run arch-chroot via ALMA:

sudo alma chroot /dev/disk/by-id/usb-Generic_USB_Flash_Disk-0:0

Create raw image and boot in qemu

For development and testing it may be useful to generate and boot the image in qemu.

Creating a 10GiB raw image, with disk encryption:

sudo alma create -e --image 10GiB almatest.img

If you receive the following error:

Error setting up a loop device: losetup: cannot find an unused loop device

Check that you are running ALMA with sudo privileges, and reboot if you have installed a kernel update since your last reboot.

Mounting the raw image to a loop device:

sudo losetup -f ./almatest.img

Check loop device:

 sudo losetup -j ./almatest.img

/dev/loop0: [2070]:6865917 (/path/to/image/almatest.img)

Note that your loop device number may differ.

Run qemu via ALMA:

sudo alma qemu /dev/loop0

This will boot the image in qemu.

Presets

Reproducing a build can be easily done using a preset file.

Preset files are simple TOML files which contain:

A list of packages to install: packages = ["mypackage"]
A post-installation script: script = """ ... """
Environment variables required by the preset (e.g. used in the script): enironment_variables = ["USERNAME"]
A list of shared directories shared_directories = ["subdirectory"] - where subdirectory would be available at /shared_dirs/subdirectory/ for use in the script of the preset.

See the presets directory for examples.

Presets are used via the --presets argument (multiple preset files or directories may be provided):

sudo ALMA_USER=archie alma create /dev/disk/by-id/usb-Generic_USB_Flash_Disk-0:0 --presets ./presets/user.toml ./presets/custom_preset.toml

Preset scripts are executed in the same order they are provided.

If a directory is provided, then all files and subdirectories in the directory are recursively crawled in alphanumeric order (all files must be ALMA .toml files). This allows you to use the following structure to compose many scripts in a specific order:

.
├── 00-add_user.toml
├── 01-xorg
│   ├── 00-install.toml
│   └── 01-config.toml
└── 02-i3
    ├── 00-install.toml
    └── 01-copy_dotfiles.toml

Example preset TOML:

packages = ["sudo"]
script = """
set -eux
useradd -m ${ALMA_USER}
passwd ${ALMA_USER}
usermod -G wheel -a ${ALMA_USER}
echo "%wheel ALL=(ALL) ALL" > /etc/sudoers.d/wheel
"""
environment_variables = ["ALMA_USER"]

Note that shared directories in the preset scripts are mounted as bind mounts, so they are not mounted read-only. Any changes the custom script makes to the shared directory will be carried out in the preset shared directory of the host system, so be sure to copy (not move) files from the shared directories.

Order of execution

ALMA installs the packages and presets in the following order:

All non-AUR packages are installed
If AUR packages are present in the toml files, yay (or another specified AUR helper) is installed
All AUR packages are installed.
Preset scripts are executed according to their filenames in alphanumeric order.

Note this may mean you have to workaround some package installations if they depend on preset scripts.

For example, at the moment you cannot install Rust-based AUR packages in the aur_packages array of the Preset TOMLs if you use rustup, since rustup needs to be given the toolchain to install first. This can be worked around by carrying out the AUR package installation inside the preset script itself in these cases.

Troubleshooting

mkinitcpio: /etc/mkinitcpio.d/linux.preset: No such file or directory

Ensure you have both the linux and base packages installed. Note that only Arch Linux is supported, not Arch Linux derivatives such as Manjaro.

r-darwish/alma

r-darwish

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