Installing Guix on Linode: a how-to

[Christopher Lemmer Webber <cwebber@dustycloud.org>]

Hi!  I finally got Guix running on Linode!  I'm excited about it!
Here's the process (thanks to jackhill on freenode for helping me figure
out all the stuff involving the bootloader!).  It's very bullet-point'y,
but here's the steps I took:

 - Start with a Debian (or whatever) server.  Be sure to add your ssh
   key for easy login.  We'll be using the default distro as a way to
   bootstrap Guix.
 - Power it down.
 - In the Disks/Configurations tab, resize the Debian disk to be
   smaller, maybe 30GB or something.
 - "Add a disk", with the following:
   - Label: "Guix"
   - Filesystem: ext4
   - Set it to the remaining size
 - Next to the "configuration" that comes with the default image,
   press "..." and select "Edit", then on that menu add to
   /dev/sdc the "Guix" label
 - Now "Add a Configuration", with the following:
   - Label: Guix
   - VM Mode: Paravirtualization (the default?? don't know if this matters)
   - 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 root@<your-server-ip-here>
 - Run the "install guix form binary installer" steps:
   - $ 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 stuff is
   below, save as guix-config.scm:

#+BEGIN_SRC scheme
(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))

  (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"))
                          ;; Is this a good idea?  Well if you don't add it
                          ;; you have to manually set your user's password
                          ;; via the glish console...
                          ("root" ,(local-file "janedoe_rsa.pub"))))))
             %base-services)))
#+END_SRC

 - Replace the following fields in the above configuration:
   - (host-name "my-server")     ; replace with your server name
   - (name "janedoe")            ; replace with your username
   - ("janedoe" ,(local-file "janedoe_rsa.pub")) ; here too
   - Note the same above for root, which I don't feel great about, but
     otherwise you'll need to log in via the linode "glish" console to
     log in as root and set the user's initial password before you can
     start using sudo (is there another way around this?)

 - Save your ssh public key (~/.ssh/id_rsa.pub) as
   <your-username-here>_rsa.pub or whatever in the same directory

 - Mount the guix drive:
     $ mkdir /mnt/guix
     $ mount /dev/sdc /mnt/guix

 - Due to the way we set things up above, we don't install Grub
   completely, just our grub configuration file.  So we need to copy
   over some of the other Grub stuff that's 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.)

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

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

BTW, if you save it as a disk image right at this point, you'll have an
easy time spinning up new Guix images!

Let me know if this guide helps you!