Development repositories as Guix channels

Development repositories as Guix channels

[Arun Isaac]

Hi,

This is with reference to the "Level 2: The repository as a channel"
section in the Guix blog post "From development environments to
continuous integration—the ultimate guide to software development with
Guix"[1]. This section describes how to convert a project repository
into a Guix channel so that the repository can double as a way to
distribute packages. I have been trying to follow the instructions and
have hit a little snag.

The post says the source field of the package definition should be a
local-file file-like object. This is fine as long as we are using `guix
build' to build packages in the repository. But, when the repository is
distributed as a channel, the local-file becomes meaningless. The
channel only has access to the sources under the .guix/modules directory
and none of the sources required to build the package itself.

It seems to me that it is not possible to distribute project
repositories as Guix channels. But hopefully, I'm missing something
simple. Could anybody please clarify?

I'm CCing Ludo since they are the author of the blog post in question,
and I'm CCing Efraim since I know they are working on something similar.

Thanks,
Arun

[1]: https://guix.gnu.org/blog/2023/from-development-environments-to-continuous-integrationthe-ultimate-guide-to-software-development-with-guix/

Re: Development repositories as Guix channels

[Daniel Meißner]

Hi Arun,

Am 6. Juli 2023 16:35:06 MESZ schrieb Arun Isaac <arunisaac@systemreboot.net>:
> 
> Hi,
> 
> This is with reference to the "Level 2: The repository as a channel"
> section in the Guix blog post "From development environments to
> continuous integration—the ultimate guide to software development with
> Guix"[1]. This section describes how to convert a project repository
> into a Guix channel so that the repository can double as a way to
> distribute packages. I have been trying to follow the instructions and
> have hit a little snag.
> 
> The post says the source field of the package definition should be a
> local-file file-like object. This is fine as long as we are using `guix
> build' to build packages in the repository. But, when the repository is
> distributed as a channel, the local-file becomes meaningless. The
> channel only has access to the sources under the .guix/modules directory
> and none of the sources required to build the package itself.
> 
> It seems to me that it is not possible to distribute project
> repositories as Guix channels. But hopefully, I'm missing something
> simple. Could anybody please clarify?

I have recently followed the instructions from this blog post as well and indeed you are right that it does not work as advertised. There's however only a small mistake in the changes for Level 2. You have to replace the relative path in the local-file form with "../.." as that gives you the root of your source tree relative to the new location of the Scheme file. Then everything works nicely. Even building the package with `guix build -f guix.scm' works from the root of the tree. Somehow Guile computes the directory relative to real file and not the symlink. Didn't expect.

Bonus: I have even setup CI via Cuirass which was surprisingly easy on a Guix system and now it rebuilds my package every time one of its inputs in Guix changes ❤️ This is awesome! Thanks for this blog post, it was inspiring.

Hope that helps

Best

-- 
Daniel

Re: Development repositories as Guix channels

[Arun Isaac]

Hi Daniel,

> You have to replace the relative path in the local-file form with
> "../.." as that gives you the root of your source tree relative to the
> new location of the Scheme file. Then everything works nicely.

Thank you! That's all I was missing. Now everything works perfectly!

> Bonus: I have even setup CI via Cuirass which was surprisingly easy on
> a Guix system and now it rebuilds my package every time one of its
> inputs in Guix changes ❤️

I'm working towards a CI system too. It's lovely!

Regards,
Arun

Re: Development repositories as Guix channels

[Ludovic Courtès]

Hi!

Arun Isaac <arunisaac@systemreboot.net> skribis:

>> You have to replace the relative path in the local-file form with
>> "../.." as that gives you the root of your source tree relative to the
>> new location of the Scheme file. Then everything works nicely.
>
> Thank you! That's all I was missing. Now everything works perfectly!

Another person reported that missing bit to me and I’ve now fixed the
blog post.  Apologies for the waste of time!

Ludo’.

Re: Development repositories as Guix channels

[Arun Isaac]

> Another person reported that missing bit to me and I’ve now fixed the
> blog post.  Apologies for the waste of time!

No worries! It's been a very enlightening blog post. Thanks for writing
it!