Re: Questions about Cuirass

[Maxime Devos]

On 20-10-2022 23:19, James Hobson wrote:
> Hello!
>
> Currently evaluating guix for embedded systems at work. But I have a few 
> questions that I can’t quite work out from the docs. Please feel no obligation 
> to answer!
>
> Please note that my guix journey is at its very beginning. I’ve not even had a 
> go at packaging!
>
> Question 1
> We would need to host the guix substitute server in an airgapped environment. 
> The server would contain plain guix packages, our in house packages, and maybe 
> patched guix packages. Would that be possible without having to rebuild the 
> entire guix package set? We don’t have so many build machines, especially not 
> for armv7.

You can tell Cuirass to only build a selection of packages (and their 
dependencies), by using a manifest, then not all of Guix is compiled but 
only what's necessary for your particular purpose.

Also, your Cuirass instance still needs access to the source code of the 
packages somehow, which will need to be somehow be squared with your 
'airgapped environment', though maybe 'copy over the result of guix 
build --sources=transitive" would be acceptable (*).

(*) except that this is after application of snippet; some kind of 
"--sources=raw,transitive" may be needed.

> Question 2 [...]

I don't know the answer to this.

> Question 3
> Our software is sadly proprietary. Is there a way for guix build to selectively 
> unpack and patch all non-proprietary sources so that we can provide it to 
> anyone who asks? I feel like if this isn’t a thing already, I guess I can write 
> it in scheme?

I assume you meant 'patch all non-proprietary' -> 'patch out all 
proprietary', such that at least the free parts can be used?

In that case, this is done already in some package definitions in Guix, 
by a 'snippet' removing parts that are non-free, such that they are not 
built and are not part of "guix build --source". (See: ‘Snippets versus 
Phases’ in the documentation, though it doesn't mention non-free things 
directly).

The Guix user can still access the unpatched source code though, by 
inspecting the package definition and removing the snippet, so it looks 
to me like that option is only good for 'you aren't allowed to modify 
this part of the source code + guix build --source must produce 
something free', not for 'you aren't allowed to see or distribute this' 
situations.

Alternatively, you could avoid all this complexity by making your 
software free.

Greetings,
Maxime.

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