Guix Paths

Guix Paths

[Buttery Pancake]

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I was looking at a NixCon 2019 session called "Guix from the Nix Perspective" (https://www.youtube.com/watch?v=bDGzCXr6VYU).

I am wondering why Guix chose `/var/guix` path instead of `/gnu/var/guix` or `/guix/var/guix`, as Nix uses `/nix/var/nix`?

I do think that having only one or two directories under root, `/gnu` and/or `/guix` is better, instead of having Guix related files under multiple directories (/var, /run etc.). It will be neat, clean and unique.

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Re: Guix Paths

[Andreas Enge]

Hello,

On Mon, Sep 21, 2020 at 01:32:52AM +0000, Buttery Pancake wrote:
> I am wondering why Guix chose `/var/guix` path instead of `/gnu/var/guix` or `/
> guix/var/guix`, as Nix uses `/nix/var/nix`?
> I do think that having only one or two directories under root, `/gnu` and/or `/
> guix` is better, instead of having Guix related files under multiple
> directories (/var, /run etc.). It will be neat, clean and unique.

I agree especially with the problem that the store database is usually
saved under /var/guix/db - it would be much nicer if the store could be
copied over from one machine to another simply by copying one directory.
But that could also be solved by moving just the database to /gnu/store/db,
I suppose.

In a similar vein, it is annoying to have to use "--localstatedir=/var"
when configuring. The default configuration should simply be, well, the
default... And then it might as well be /gnu, too.

Andreas

Re: Guix Paths

[Tobias Geerinckx-Rice]

Pancake,

On 2020-09-21 3:32, Buttery Pancake wrote:
> I was looking at a NixCon 2019 session called "Guix from the Nix 
> Perspective" (https://www.youtube.com/watch?v=bDGzCXr6VYU).

Bookmarked, thanks!

> I am wondering why Guix chose `/var/guix` path instead of 
> `/gnu/var/guix` or `/guix/var/guix`, as Nix uses `/nix/var/nix`?

Only Ludo' can answer this, but I think it's an attempt to follow 
FHS/GNU directory standards.  Similar to how --localstatedir is wrong by 
default.

I considered it a bike shed until recently, when I first heard of people 
putting /gnu and /var on separate btrfs subvolumes for snapshotting.  A 
bad idea on most distributions, of course, but Guix's database and store 
really are one unit -- like data and metadata.  If your database gets 
corrupted, lost, or significantly out of sync, Guix will happily delete 
store items to match it, up to and including the last glibc.  Ask me how 
I know.

> I do think that having only one or two directories under root, `/gnu` 
> and/or `/guix` is better, instead of having Guix related files under 
> multiple directories (/var, /run etc.). It will be neat, clean and 
> unique.

Moving the database to /gnu makes sense, but the rest of /var/guix 
belongs in /var.  Same for /run: it's the right place for what's there.  
Don't let's reinvent the FHS poorly under /gnu.  It's already pretty 
neat, and we're already unique.

Kind regards,

T G-R

Sent from a Web browser. Excuse or enjoy my brevity.

Re: Guix Paths

[Ricardo Wurmus]

> I am wondering why Guix chose `/var/guix` path instead of
> `/gnu/var/guix` or `/guix/var/guix`, as Nix uses `/nix/var/nix`?

I think there’s no better reason than to say that /var is the
conventional local state directory on GNU systems.

It’s possible to use /gnu/var/guix, of course; on the HPC cluster at the
MDC we use /gnu/var as the localstatedir, but it’s not as convenient as
it may seem, because that directory contains the profile directories,
which need to be user-writable, whereas the rest of /gnu only need to be
writable by the daemon.  This means that we end up mounting the same
directories more than once with different permissions.

Users can pick anything for the localstatedir during the configure step
and “guix pull” should respect that choice in the long term.

-- 
Ricardo

Re: Guix Paths

[Buttery Pancake]

> which need to be user-writable, whereas the rest of /gnu only need to be
> writable by the daemon. This means that we end up mounting the same
> directories more than once with different permissions.

Yes. As default, wouldn't it be better to use `/guix/guix-var-stuff` instead of `/var/guix/guix-var-stuff`? Also, bringing `/run/guix-other-stuff` under `/guix/guix-other-stuff`.

This way, `/gnu` and `/guix` will be unique and be easily tracked, backed-up, snap-shot, mounted-separately or won't interfere with other stuffs on file-system (like ever).

Re: Guix Paths

[Tobias Geerinckx-Rice]

Hi!

On 2020-09-21 16:45, Buttery Pancake wrote:
>> which need to be user-writable, whereas the rest of /gnu only need to 
>> be
>> writable by the daemon. This means that we end up mounting the same
>> directories more than once with different permissions.
> 
> Yes. As default, wouldn't it be better to use `/guix/guix-var-stuff`
> instead of `/var/guix/guix-var-stuff`? Also, bringing
> `/run/guix-other-stuff` under `/guix/guix-other-stuff`.

/run is ephemeral: it is required to be a tmpfs on ‘modern’ system(d)s, 
and to be at least emptied at boot on others.  Thus nothing in it should 
ever be

> backed-up, snap-shot, [or] mounted-separately [more than it already is 
> today.]

As for

> won't interfere with other stuffs on file-system (like ever).

I don't think it interferes, does it?  How?

I think adding yet another non-standard / subdirectory should be done 
only for very good reason.  /gnu has it, so would moving to /gnu/db/, 
but I don't see a case for the others to be moved.

Kind regards,

T G-R

Sent from a Web browser. Excuse or enjoy my brevity.