artnoiNov 20, 2023
ALI is my latest big project, arising from my itch to create something like cloud-init but with very focused goals in mind.
The result is a somewhat small but very simple mechanism for preparing a new Arch Linux system. ALI was first meant to be a big web of shell scripts, but later evolved into just a declarative YAML specification.
It is designed based on my own experience of maintaining Arch Linux systems as hobby and at my previous job.
ali-rs is the reference implementation for ALI, with manifest validation and other features aimed at simplifying and standardizing Arch Linux installations.
Users can use ALI and ali-rs to create somewhat reproducible Arch Linux systems.
The most clear difference between ALI and cloud-init is that ALI is just a YAML specification, while cloud-init is a full-fledged platform for configuring Linux machines for the cloud, and comes with its own set of mostly Python tools.
Unlike cloud-init and autoinstall, ALI does not aim to always create a full, bootable system. Parts of the declaration can be omitted, and ALI can be used to just bootstrap a new chroot environment.
This allows ALI users to use ALI to create an Arch Linux system anywhere; users can use ALI for creating a new Arch environment on a real disk with a bootloader, or as chroot mountpoints.
While cloud-init is more fully-featured, it can be an overkill for (my) personal use, and the feedback users get from applying the cloud-init manifests is not instant - you’d need to reboot to re-apply cloud-init manifests.
Users can even just use ALI to partition their disks for them, while the users perform the actual installation.
Or users can manually partition the disks before using ALI to populate/configure the systems.
Another difference is that cloud-init is run at boot time, right before the system fully boots, while ALI, as a standard, does not have this limitation.
After the spec is published, I began working on a reference implementation.
ali-rs is that implementation, written in Rust because I wanted to learn the language.
This implementation is a single binary Rust program, and it fully supports all of ALI features, with its own extra features not found in ALI, like manifest validation.
ali-rs is currently 70-80% done, with all of ALI features implemented but not yet completely tested. I occasionally use it to install Arch Linux to new Vultr VPS.
ali-rs has manifest validation built-in and enabled by default, which means that, if there’s no bug (ahem), ali-rs would never wipe your data on existing block devices. This makes ali-rs safe to use on non-clean slate scenarios.
In addition to arbitary shell commands, ali-rs also features its own sub-language called hooks, which are just simple text interface for configuring Arch Linux systems in an opinionated way.
This means that even though ALI does not have boot features, users still have the means to provide bootloader configuration programmatically via shell scripts or ali-rs hooks.