Guix Machines

• Repository Structure
  • User Supplied Files Required for Push Based Deployment
  • Guix Channel Files
    • Updating guix channels used for deployment
  • guix-machines the Guix Channel
• Initializing a System
  • Using an existing guix installation image
    • Producing an installation image
    • Setup Installation
    • Configure Guix Channels
    • Disk Setup and Partitioning
    • Bootstrap System
      • Start cow-store Service
      • Optional (but recommended): Use additional or alternative substitute servers
      • Create and Bootstrap System
  • Producing an image to be flashed directly
• Push Deployment with guix deploy
• Pull Based Deployment
• Using Local Sources
  • Building Operating System Configuration
  • Running Operating System in VM for testing
  • Generating the OS service extension graph
  • Generating the shepherd service graph
  • Push Based Deployments
  • Pull Based Deployments
• Footnotes

Guix configurations for all Guix powered servers privately managed by the author. This includes all virtual machines for my home network and cloud/vps instances. Two mutable deployment methodologies are supported:

1. A push based model, using guix deploy¹ to remotely deploy changes (useful for example from ci/cd).
2. A pull based model, using guix directly from the target, along with either the entire repository, or its channel file.

Immutable deployment is not yet supported, but is certainly possible given Guix's ability to build an operating-system configuration into a image.

Repository Structure

channels*.scm

Guix channel files

deploy/

Folder containing all guix deploy configurations

.gitignore

Files ignored by git

.guix/

Guix channel directory

.guix-authorizations

Guix authorizations file²

.guix-channel

Guix channel file³

.pub-keys/

Folder containing public key files used by Guix configurations

README.org

Org-mode⁴ documentation

TODO.org

Org-mode todo's, known issues and future aspirations

unguix/

Docker/docker-compose files used on deployed instances, managed outside of guix. Once better support for running docker/docker-compose via shepherd, specified declaratively via Guix configuration has been implemented, this directory and all files within it should be able to be removed.

User Supplied Files Required for Push Based Deployment

.deploy-key

Private ssh key used to deploy changes to the target.

Guix Channel Files

Guix channels⁵ allow for Guix to be customized and extended. They are also critical for replicating a Guix system⁶. As mentioned above, there are two primary classes of deployments that are managed using this repository, push based and pull based. In both cases, what specific versions of software that will be installed during deployment depends on the guix channels in use. To ensure reproducibility, a channels.scm file is provided in this repository that is expected to be used during deployment. It pins external guix channels to specific versions.

If for some reason channels need to be pinned for a specific deployment, a new channel file named channels-<hostname>.scm can be created and used in place of normally used channel file.

TODO Updating guix channels used for deployment

This doesn't work right unless your channels match what is expected by this repository.

  guix time-machine -- describe -f channels > channels.scm

guix-machines the Guix Channel

This repository is itself a Guix channel, which allows operating-system configurations to come directly from the channel, and the version of this configuration be managed just like any other guix channel. It also facilitates CI, allowing for changes this channel be evaluated by Cuirass at https://guix-ci.home.rekahsoft.ca⁷. This channel does not define any packages, only system configurations and machine specifications for deployment.

At a later date, this also will allow for building of machine images for immutable deployment, bootstrapping and more.

TODO Initializing a System

Using an existing guix installation image

TODO Producing an installation image

TODO: It would be convent to be able to produce an image that can be used to install my normal setup. This would avoid pulling my channels, as well as downloading software (it could all be pre-packaged in the image).

If you produce and use this installation image, you can skip to Disk Setup and Partitioning.

TODO Setup Installation

TODO: network needs to be setup; local, keymap, and font too.

Configure Guix Channels

First, fetch the most recent channel file from the target machine. For most, this will be done via the internet using my public mirror.

  curl -O https://git.rekahsoft.ca/rekahsoft/guix-machines/raw/branch/master/channels.scm

When on my network, I pull from my internal git (notice the different URL).

  curl -O https://git.home.rekahsoft.ca/rekahsoft-public/guix-machines/raw/branch/master/channels.scm

Once the channel file is available on the target, refresh the cached command paths with hash and update guix to use the new channels.

  hash guix
  sudo -i guix pull -C $(realpath channels.scm)

TODO Disk Setup and Partitioning

TODO: disks need to be partitioned and appropriately mounted. This varies depending on the setup.

  # Create disk partition table and layout
  parted /dev/nvme0n1 mklabel gpt

  # Create partitions
  parted /dev/nvme0n1 mkpart primary ESP 0% 512MiB
  parted /dev/nvme0n1 mkpart 512MiB 100%

  # Create EFI partition
  parted /dev/nvme0n1p1 set 1 esp on
  mkfs.fat -F32 /dev/nvme0n1p1

  # Create LUKS container on remainder of disk
  cryptsetup luksFormat --label crypt /dev/nvme0n1p2

  # Unlock LUKS container after creation
  cryptsetup luksOpen /dev/nvme0n1p2 crypt

  #
  # Create LVM2 container inside of LUKS container

  # Create Physical Volume (pv)
  pvcreate /dev/mapper/crypt

  # Create Volume Group (vg)
  vgcreate vg0 /dev/mapper/crypt

  # Create Logical Volume/s (vg)
  lvcreate -L <ROOT_VOL_SIZE>G vg0 -n root
  lvcreate -l +100%FREE vg0 -n swap

  #
  # Create btrfs 'pool' (file-system) and subvolumes

  # Create btrfs file-system
  mkfs.btrfs --label root /dev/vg0/root

  # Create btrfs subvolumes
  mount /dev/vg0/root /mnt
  btrfs subvolume create /mnt/@
  umount /mnt

  # Mount the root subvolume.
  mount -o subvol=@,compress=zstd /dev/vg0/root /mnt

  # Create nested subvolumes for /gnu/store, /home, and /var
  mkdir -p /mnt/gnu
  btrfs subvolume create /mnt/gnu/store
  btrfs subvolume create /mnt/home
  btrfs subvolume create /mnt/var

  # Create and activate swap
  mkswap --label swap /dev/vg0/swap
  swapon /dev/vg0/swap

  # Prepare /mnt for Guix installation
  mkdir -p /mnt/boot/efi
  mount /dev/nvme0n1p1 /mnt/boot/efi

Bootstrap System

Start cow-store Service

As described in guix documentation, start cow-store to allow later steps to write store changes to /mnt/gnu/store.

  herd start cow-store /mnt

Optional (but recommended): Use additional or alternative substitute servers

Optionally additional or alternative substitute servers can be setup for guix-daemon. This is recommended to greatly speed up installation (so that nonguix and rekahsoft-guix (internal network only) substitutes can be used).

First stop the running guix-daemon.

  herd stop guix-daemon

Then start a new instance of guix-daemon as it is normally started by its Shepherd service, but with additional or alternative substitute servers provided.

  guix-daemon \
    --build-users-group guixbuild \
    --max-silent-time 0 \
    --timeout 0 \
    --log-compression gzip \
    --discover=no \
    --substitute-urls https://substitutes.nonguix.org https://guix-ci.home.rekahsoft.ca https://ci.guix.gnu.org https://bordeaux.guix.gnu.org &

Create and Bootstrap System

Create a bootstrap.scm file like this:

  (@ (rekahsoft guix-config vms <target>) %system)

Use guix system init ... to instantiate the system.

  guix system init bootstrap.scm /mnt

TODO Producing an image to be flashed directly

TODO: there are limitations on what images I can produce; namely, lvm and luks cannot be setup easily (or at all?) it seems?

  guix time-machine -C channels.scm -- system image -e '(@ (rekahsoft guix-config vms <target>) %image)'

Push Deployment with guix deploy

Push based mutable deployment is the default deployment methodology for the majority of systems managed by this repository. This is particularity safe because Guix changes are done as transactions, and thus can easily be rolled back.

To deploy a system use the following (substituting <hostname> with the appropriate deploy file).

  guix time-machine -C channels.scm -- deploy deploy/<hostname>.scm

Note: Deploy files in /rekahsoft/guix-machines/src/commit/404ba02704e5cfb7fb3ca6aea5ad84e860373f1d/deploy are named after the hostname that would be used to ssh to the machine.

Pull Based Deployment

Pull based mutable deployment is the default deployment methodology for personal computers, where using a push based method doesn't make sense. It also serves as a secondary deployment mechanism for systems normally maintained using the push deployment model; for example, this becomes necessary when facing guix deploy bugs.

First Configure Guix Channels as described above. Once channels have been updated successfully, use the following to reconfigure the system.

  sudo -i guix system reconfigure -e '(@ (rekahsoft guix-config vms <target>) %system)'

Alternatively, the same effect can be achieved without first pulling the appropriate channels by instead using guix time-machine as follows.

  sudo -i guix time-machine -C $(realpath channels.scm) -- system reconfigure -e '(@ (rekahsoft guix-config vms <target>) %system)'

Using Local Sources

Regardless of the deployment methodology used, sometimes it is useful to deploy changes that have not yet been committed. This should be done sparingly, as it can be slightly confusing if forgotten; that being said, Guix makes this a semi-reasonable thing to do, as how the system changes is tracked very explicitly by guix generations local to the target.

To manually deploy using local sources, the local sources must exist on the working machine (of course). The easiest way to do this is via git, from the working machine like so. Most will pull from my public git mirror.

  git clone https://git.rekahsoft.ca/rekahsoft/guix-machines.git

On my network, internal git is used instead (notice the different URL).

  git clone https://git.home.rekahsoft.ca/rekahsoft-public/guix-machines.git

Once a copy of the sources are available on the working machine, all that remains is following the normal deployment steps, but with a slight modification; use the -L|--load-path argument to specify the current working sources, effectively overriding what is in the guix-machines channel.

Building Operating System Configuration

Many times its useful to verify that a change to a system configuration will build correctly, prior to deploying it. guix system build is meant for exactly this, and can be run as follows.

  guix time-machine -C channels.scm -- system build -L .guix -e '(@ (rekahsoft guix-config vms <target>) %system)'

Running Operating System in VM for testing

  $(guix time-machine -C channels.scm -- system vm -e '(@ (rekahsoft guix-config vms <target>) %system)') -m 2G -smp 2 -nic user,model=virtio-net-pci

Generating the OS service extension graph

  guix time-machine -C channels.scm -- system extension-graph -e '(@ (rekahsoft guix-config vms <target>) %system)' | guix shell xdot -- xdot -

Generating the shepherd service graph

  guix time-machine -C channels.scm -- system shepherd-graph -e '(@ (rekahsoft guix-config vms <target>) %system)' | guix shell xdot -- xdot -

Push Based Deployments

  guix time-machine -C channels.scm -- deploy -L ./.guix deploy/<hostname>.scm

See the Push Deployment with guix deploy section for more details.

Pull Based Deployments

  sudo -i guix time-machine -C $(realpath channels.scm) -- system reconfigure -L $(realpath ./.guix) -e '(@ (rekahsoft guix-config vms <target>) %system)'

See the Pull Based Deployment section for more details.

Footnotes

---

¹

https://guix.gnu.org/manual/en/html_node/Invoking-guix-deploy.html

²

https://guix.gnu.org/manual/en/html_node/Channel-Authentication.html

³

https://guix.gnu.org/manual/en/html_node/Package-Modules-in-a-Sub_002ddirectory.html

⁴

https://orgmode.org/

⁵

https://guix.gnu.org/manual/en/html_node/Channels.html

⁶

https://guix.gnu.org/manual/en/html_node/Replicating-Guix.html

⁷

Only available in my internal home-network