Guix

Running Guix System on a Linode Server

Joshua Branson, Christopher Lemmer Webber — 6 octobre 2020

Christopher Lemmer Webber recently discovered how to run Guix System on a Linode server. The below guide details how to set up your Linode server to run Guix System. We invite you to run your website using Guix system!

To run Guix on a server hosted by Linode, start with a recommended Debian server. We recommend using the default distro as a way to bootstrap Guix. Create your SSH keys.

ssh-keygen

Be sure to add your SSH key for easy login to the remote server. This is trivially done via Linode's graphical interface for adding SSH keys. Go to your profile and click add SSH Key. Copy into it the output of:

cat ~/.ssh/<username>_rsa.pub

Power the Linode down. In the Linode's Disks/Configurations tab, resize the Debian disk to be smaller. 30 GB is recommended.

In the Linode settings, choose Add a disk with the following:

• Label: Guix
• Filesystem: ext4
• Set it to the remaining size

On the configuration field that comes with the default image, press ... and select Edit, then on that menu add to /dev/sdc the Guix label.

Now select Add a Configuration, with the following:

• Label: Guix
• Kernel: GRUB 2 (it's at the bottom! This step is important!

• Block device assignment:

  • /dev/sda: Guix
  • /dev/sdb: swap
• Root device: /dev/sda
• Turn off all the filesystem/boot helpers.

Now power it back up, picking the Debian configuration. Once it's booted up, ssh in your server via ssh root@<your-server-IP-here>. (You can find your server IP address in your Linode Summary section.) Now you can run the binary installation as explained in the manual:

sudo apt-get install gpg
wget https://sv.gnu.org/people/viewgpg.php?user_id=15145 -qO - | gpg --import -
wget https://git.savannah.gnu.org/cgit/guix.git/plain/etc/guix-install.sh
chmod +x guix-install.sh
./guix-install.sh
guix pull

Now it's time to write out a config for the server. The key information is below. Save the resulting file as guix-config.scm.

(use-modules (gnu)
             (guix modules))
(use-service-modules networking
                     ssh)
(use-package-modules admin
                     certs
                     package-management
                     ssh
                     tls)

(operating-system
  (host-name "my-server")
  (timezone "America/New_York")
  (locale "en_US.UTF-8")
  ;; This goofy code will generate the grub.cfg
  ;; without installing the grub bootloader on disk.
  (bootloader (bootloader-configuration
               (bootloader
                (bootloader
                 (inherit grub-bootloader)
                 (installer #~(const #t))))))
  (file-systems (cons (file-system
                        (device "/dev/sda")
                        (mount-point "/")
                        (type "ext4"))
                      %base-file-systems))
  (swap-devices (list "/dev/sdb"))

  (initrd-modules (cons "virtio_scsi"    ;needed to find the disk
                        %base-initrd-modules))

  (users (cons (user-account
                (name "janedoe")
                (group "users")
                ;; Adding the account to the "wheel" group
                ;; makes it a sudoer.
                (supplementary-groups '("wheel"))
                (home-directory "/home/janedoe"))
               %base-user-accounts))

  (packages (cons* nss-certs            ;for HTTPS access
                   openssh-sans-x
                   %base-packages))

  (services (cons*
             (service dhcp-client-service-type)
             (service openssh-service-type
                      (openssh-configuration
                       (openssh openssh-sans-x)
                       (password-authentication? #f)
                       (authorized-keys
                        `(("janedoe" ,(local-file "janedoe_rsa.pub"))
                          ("root" ,(local-file "janedoe_rsa.pub"))))))
             %base-services)))

Replace the following fields in the above configuration:

(host-name "my-server")       ; replace with your server name
; if you chose a linode server outside the U.S., then
; use tzselect to find a correct timezone string
(timezone "America/New_York") ; if needed replace timezone
(name "janedoe")              ; replace with your username
("janedoe" ,(local-file "janedoe_rsa.pub")) ; replace with your ssh key
("root" ,(local-file "janedoe_rsa.pub")) ; replace with your ssh key

The last line in the above example lets you log into the server as root and set the initial root password. After you have done this, you may delete that line from your configuration and reconfigure to prevent root login.

Save your ssh public key (eg: ~/.ssh/id_rsa.pub) as <your-username-here>_rsa.pub and your guix-config.scm in the same directory. In a new terminal run these commands.

sftp root@@<remote server ip address>
put /home/<username>/ssh/id_rsa.pub .
put /path/to/linode/guix-config.scm .

In your first terminal, mount the guix drive:

mkdir /mnt/guix
mount /dev/sdc /mnt/guix

Due to the way we set things up above, we do not install GRUB completely. Instead we install only our grub configuration file. So we need to copy over some of the other GRUB stuff that is already there:

mkdir -p /mnt/guix/boot/grub
cp -r /boot/grub/* /mnt/guix/boot/grub/

Now initialize the Guix installation:

guix system init guix-config.scm /mnt/guix

Ok, power it down! Now from the Linode console, select boot and select Guix.

Once it boots, you should be able to log in via SSH! (The server config will have changed though.) You may encounter an error like:

$ ssh root@<server ip address>
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the ECDSA key sent by the remote host is
SHA256:0B+wp33w57AnKQuHCvQP0+ZdKaqYrI/kyU7CfVbS7R4.
Please contact your system administrator.
Add correct host key in /home/joshua/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /home/joshua/.ssh/known_hosts:3
ECDSA host key for 198.58.98.76 has changed and you have requested strict checking.
Host key verification failed.

Either delete ~/.ssh/known_hosts file, or delete the offending line starting with your server IP address.

Be sure to set your password and root's password.

ssh root@<remote ip address>
passwd  ; for the root password
passwd <username> ; for the user password

You may not be able to run the above commands at this point. If you have issues remotely logging into your linode box via SSH, then you may still need to set your root and user password initially by clicking on the Launch Console option in your linode. Choose the Glish instead of Weblish. Now you should be able to ssh into the machine.

Hooray! At this point you can shut down the server, delete the Debian disk, and resize the Guix to the rest of the size. Congratulations!

By the way, if you save it as a disk image right at this point, you'll have an easy time spinning up new Guix images! You may need to down-size the Guix image to 6144 MB, to save it as an image. Then you can resize it again to the max size.

That's all for today! We hope you have fun playing with your brand new Guix System Server!

A variant of this guide is available in the Guix Cookbook.

About GNU Guix

GNU Guix is a transactional package manager and an advanced distribution of the GNU system that respects user freedom. Guix can be used on top of any system running the kernel Linux, or it can be used as a standalone operating system distribution for i686, x86_64, ARMv7, and AArch64 machines.

In addition to standard package management features, Guix supports transactional upgrades and roll-backs, unprivileged package management, per-user profiles, and garbage collection. When used as a standalone GNU/Linux distribution, Guix offers a declarative, stateless approach to operating system configuration management. Guix is highly customizable and hackable through Guile programming interfaces and extensions to the Scheme language.