bug#54631: Unable to determine system origin when configuration stored in guix channel

bug#54631: Unable to determine system origin when configuration stored in guix channel

[Collin J. Doering via Bug reports for GNU Guix]

Hi,

I recently converted my guix configuration to be stored in a channel, primarily to allow me to reference files in the repository but yet still have a self-contained configuration. It also allows me to easily build packages and images from my local guix instance.  I also like how the specification of my system (or home) is precisely defined by a set of channels, and an expression which evaluates to the operating-system (or home-configuration) that I'm deploying.

As per the guix manual:

--8<---------------cut here---------------start------------->8---
If you want configuration.scm to be self-contained, we recommend that modules or files it refers to be part of a channel.
--8<---------------cut here---------------end--------------->8---

This all being said, I noticed an issue in that I'm unable to determine the provenance of a system when my configuration is stored in a guix channel.

Specifically, if I have a guix channel that contains two modules, each of which exports a %system variable of type operating-system, I cannot tell which one was used to instantiate the system. This is due to two issues. The first is because when `-e|--expression` arguments are used, `configuration-file` is set to `#f` in the generations provenance file but the expression itself is not stored in the provenance file, and is not listed in `guix system describe`, `guix system list-generations`, etc.. commands.

--8<---------------cut here---------------start------------->8---
sudo -i guix system reconfigure -e '(@ (my config system-a) %system)'
--8<---------------cut here---------------end--------------->8---

--8<---------------cut here---------------start------------->8---
➜ guix system describe        
Generation 30	Mar 28 2022 22:50:55	(current)
  file name: /var/guix/profiles/system-30-link
  canonical file name: /gnu/store/886xwflic0dnf86d460yf7n5wg3jng7w-system
  label: GNU with Linux 5.16.16
  bootloader: grub-efi
  root device: label: "root"
  kernel: /gnu/store/44hi9qg3mrp6c6cb1rqwx47xhg1663d9-linux-5.16.16/bzImage
  channels:
    guix:
      repository URL: https://git.savannah.gnu.org/git/guix.git
      branch: master
      commit: e584a093f943be216fdc93895281fde835836b8d
    my-config-channel:
      repository URL: https://not-yet-on-the-internet.com
      branch: master
      commit: 918a3bf799038a019c7394cda480ee67db8a0009
--8<---------------cut here---------------end--------------->8---

Change the system to 'system-b':

--8<---------------cut here---------------start------------->8---
sudo -i guix system reconfigure -e '(@ (my config system-b) %system)'
--8<---------------cut here---------------end--------------->8---

--8<---------------cut here---------------start------------->8---
➜ guix system describe        
Generation 31	Mar 28 2022 23:10:01	(current)
  file name: /var/guix/profiles/system-31-link
  canonical file name: /gnu/store/jpkxxyh6zi3gh8pbml3r9l1iccibw5mk-system
  label: GNU with Linux 5.16.16
  bootloader: grub-efi
  root device: label: "root"
  kernel: /gnu/store/jpkxxyh6zi3gh8pbml3r9l1iccibw5mk-linux-5.16.16/bzImage
  channels:
    guix:
      repository URL: https://git.savannah.gnu.org/git/guix.git
      branch: master
      commit: e584a093f943be216fdc93895281fde835836b8d
    my-config-channel:
      repository URL: https://not-yet-on-the-internet.com
      branch: master
      commit: 918a3bf799038a019c7394cda480ee67db8a0009
--8<---------------cut here---------------end--------------->8---

Notice how there is no way to see which configuration was used to create the system.


The second issue is that when `-L|--load-path` is used along with either a file or expression to specify the operating-system or home-configuration, it essentially 'tarnishes' the provenance of the system, in that the following deployment is not differentiable from the preceding one/s, despite them being different.

--8<---------------cut here---------------start------------->8---
sudo -i guix system reconfigure -L my-local-channel-but-with-changes -e '(@ (my config system-a) %system)'
--8<---------------cut here---------------end--------------->8---

--8<---------------cut here---------------start------------->8---
➜ guix system describe        
Generation 32	Mar 28 2022 23:10:01	(current)
  file name: /var/guix/profiles/system-32-link
  canonical file name: /gnu/store/s1f82wy0mj1zv3jvrzzc86h86zrdv336-system
  label: GNU with Linux 5.16.16
  bootloader: grub-efi
  root device: label: "root"
  kernel: /gnu/store/s1f82wy0mj1zv3jvrzzc86h86zrdv336-linux-5.16.16/bzImage
  channels:
    guix:
      repository URL: https://git.savannah.gnu.org/git/guix.git
      branch: master
      commit: e584a093f943be216fdc93895281fde835836b8d
    my-config-channel:
      repository URL: https://not-yet-on-the-internet.com
      branch: master
      commit: 918a3bf799038a019c7394cda480ee67db8a0009
--8<---------------cut here---------------end--------------->8---

Thank you for reading

-- 
Collin J. Doering

http://rekahsoft.ca
http://blog.rekahsoft.ca
http://git.rekahsoft.ca

bug#54631: Unable to determine system origin when configuration stored in guix channel

[Liliana Marie Prikler]

Am Dienstag, dem 29.03.2022 um 22:03 -0400 schrieb Collin J. Doering:
> [...]
> Notice how there is no way to see which configuration was used to
> create the system.
The key here is that you're using a configuration expression rather
than a file.  Were you to write those files to disk in let's say
config-a.scm and config-b.scm respectively and refer to them on the
command line like that, you'd have a configuration file guix could
refer to.

Alternatively, Guix could take the expression specified via -e and
write it to disk.  Note that some configuration files are meaningless
even if written to disk, for example...

> The second issue is that when `-L|--load-path` is used along with
> either a file or expression to specify the operating-system or home-
> configuration, it essentially 'tarnishes' the provenance of the
> system, in that the following deployment is not differentiable from
> the preceding one/s, despite them being different.
> 
> --8<---------------cut here---------------start------------->8---
> sudo -i guix system reconfigure -L my-local-channel-but-with-changes
> -e '(@ (my config system-a) %system)'
> --8<---------------cut here---------------end--------------->8---
> 
> --8<---------------cut here---------------start------------->8---
> ➜ guix system describe        
> Generation 32   Mar 28 2022 23:10:01    (current)
>   file name: /var/guix/profiles/system-32-link
>   canonical file name: /gnu/store/s1f82wy0mj1zv3jvrzzc86h86zrdv336-
> system
>   label: GNU with Linux 5.16.16
>   bootloader: grub-efi
>   root device: label: "root"
>   kernel: /gnu/store/s1f82wy0mj1zv3jvrzzc86h86zrdv336-linux-
> 5.16.16/bzImage
>   channels:
>     guix:
>       repository URL: https://git.savannah.gnu.org/git/guix.git
>       branch: master
>       commit: e584a093f943be216fdc93895281fde835836b8d
>     my-config-channel:
>       repository URL: https://not-yet-on-the-internet.com
>       branch: master
>       commit: 918a3bf799038a019c7394cda480ee67db8a0009
> --8<---------------cut here---------------end--------------->8---
LOAD_PATH tweaking should be considered harmful and void your
provenance, at least w.r.t. channels.  There's no sane way for guix to
check whether the load paths you added still exist after
reconfiguration, other than placing the entire directory in the store.

Cheers

bug#54631: Unable to determine system origin when configuration stored in guix channel

[Collin J. Doering via Bug reports for GNU Guix]

Hi Liliana,

Thank you for your response :)

> Alternatively, Guix could take the expression specified via -e and
> write it to disk. 

I think this would be the best way to resolve this issue. Also, thanks for your explanation.

> LOAD_PATH tweaking should be considered harmful and void your
> provenance, at least w.r.t. channels.  There's no sane way for guix to
> check whether the load paths you added still exist after
> reconfiguration, other than placing the entire directory in the store.

I agree! However, I think it would be nice if `guix system describe`, `guix system list-generations`, `guix home list-generations`, etc.. indicated when a generation was created with the `-L|--load-path` argument specified. As you said, it 'voids you provenance', so I think its something that should be visually indicated to the user.

Regards

-- 
Collin J. Doering

http://rekahsoft.ca
http://blog.rekahsoft.ca
http://git.rekahsoft.ca