Erase / on boot

This issue tracks the creation of a Guix System implementation of

https://grahamc.com/blog/erase-your-darlings:

"I erase my systems at every boot.

[...]

NixOS can boot with only two directories: /boot, and /nix."

I have a working prototype of

https://elis.nu/blog/2020/05/nixos-tmpfs-as-root/. I will submit some

small fixes in the short term, and later some larger patches.

Ideally this will result in a cookbook entry, and a CI test.

Adventures so far...

I've pasted a working system configuration at the bottom.

The idea is to boot / as tmpfs, and to mount the minimal set of

directories from persistent storage:

What's working:

A few issues:

partitions, and getting it wrong can easily make your system unbootable.

Suggestions? Maybe the user could set up bind-mounts to map to their

preferred partition scheme? A basic cookbook entry could bind-mount

directories from a single ext4 partition to the required directories.

https://guix.gnu.org/cookbook/en/html_node/Setting-up-a-bind-mount.html,

but this didn't seem to work from initrd: the kernel panic'd on boot. I

need to confirm this and raise a bug.

forever on boot. I need to confirm this and raise a bug.

https://issues.guix.gnu.org/51548 fixes this.

Here's the config:

(use-modules (gnu))

(use-service-modules desktop networking ssh xorg)

(operating-system

(timezone "Australia/Sydney")

(host-name "test")

(users (cons* (user-account

(name "tom")

(comment "Tom")

(group "users")

(home-directory "/home/tom")

;; Needed since /etc/passwd is not persisted.

(password (crypt "password" "foobar"))

(supplementary-groups

'("wheel" "netdev" "audio" "video")))

%base-user-accounts))

(packages

(append

(list

(specification->package "emacs-next"))

%base-packages))

(services

(append

(list (service gnome-desktop-service-type)

(set-xorg-configuration

(xorg-configuration

(keyboard-layout keyboard-layout))))

%desktop-services))

(bootloader

(bootloader-configuration

(bootloader grub-bootloader)

(target "/dev/sda")

(keyboard-layout keyboard-layout)))

(file-systems

(cons* (file-system

(mount-point "/")

(device

;; TODO: Raise bug that root-as-tmpfs falsely requires a partition.

(uuid "59457d60-2b08-4f5c-b1c7-e29cd5f7a3da"

'btrfs))

(options "size=1G")

(type "tmpfs"))

(file-system

(mount-point "/boot")

(device

(uuid "59457d60-2b08-4f5c-b1c7-e29cd5f7a3da"

'btrfs))

(options "subvol=boot")

(needed-for-boot? #t)

(type "btrfs"))

(file-system

(mount-point "/home")

(device

(uuid "59457d60-2b08-4f5c-b1c7-e29cd5f7a3da"

'btrfs))

(options "subvol=home")

(type "btrfs"))

(file-system

(mount-point "/var/guix")

(device

(uuid "59457d60-2b08-4f5c-b1c7-e29cd5f7a3da"

'btrfs))

(options "subvol=var/guix")

;; Needed to boot old generations, which needs /var/guix/profiles/

(needed-for-boot? #t)

(type "btrfs"))

(file-system

(mount-point "/gnu")

(device

(uuid "59457d60-2b08-4f5c-b1c7-e29cd5f7a3da"

'btrfs))

(options "subvol=gnu")

(needed-for-boot? #t)

(type "btrfs"))

%base-file-systems)))

On 1/11/21 23:19, Tom Fitzhenry wrote:

Another issue: /var/tmp/ is not created on boot, which breaks vi:

tom@computer ~/src$ vi

ex/vi: Error: /var/tmp/vi.recover: No such file or directory

ex/vi: Modifications not recoverable if the session fails

ex/vi: Error: /var/tmp/vi.recover/vi.u8Kkbb: No such file or directory

Hi Tom,

Tom Fitzhenry <tom@tom-fitzhenry.me.uk> writes:

While interesting, this effort is not an actual bug and is a WIP it

seems, so I'm closing it.

Feel free to share progress or ask for guidance or guix-devel@gnu.org!

Thanks!

Maxim