Re: [PATCH] doc: Mention "guix pull" during installation.

[Leo Famulari <leo@famulari.name>]

On Fri, Dec 16, 2016 at 09:38:02AM +0100, Petter wrote:
> good experience because of this. Proposing a patch to add this to the
> manual.

Thanks for looking out for the new user experience, which one tends to
forget as time passes :)

> * doc/guix.texi (Proceeding with the Installation): Add "guix pull".

> +At this point it is advisable to update the system, especially if the
> +installer is more than a few weeks old. Then most, if not all, packages
> +will be available as substitutes.
> +
> +@example
> +guix pull
> +@end example

So far, in practice, this seems to become necessary as a given release
grows old. This is a negative side effect of some limitations of our
build farm infrastructure.

Specifically, we start to garbage collect the substitutes that
correspond to a release as time goes by, for two reasons: we need the
disk space, and more importantly, our method of registering garbage
collector roots [0] is still rather crude.

Some of us are working on a different method of registering garbage
collector roots that will allow us to tell Hydra, "Keep the substitutes
for release X", or "Keep the substitutes for the master branch in the
last 3 months".

I've recently gave an explanation of why I think using `guix pull`
before installing GuixSD should not be recommended unconditionally:

http://lists.gnu.org/archive/html/bug-guix/2016-11/msg00047.html

In the specific case of installing GuixSD 0.11.0 today, `guix pull` is
necessary, because we lack the substitutes, and some packages can't be
built at all now [1]. But, adding these lines to the manual now won't
make it show up in the 0.11.0 installer manual.

I think we should work on improving our infrastructure in the next
release cycle, and revisit this change to the manual if we are still
having problems before the 0.13.0 release.

What does everyone think?

[0]
https://www.gnu.org/software/guix/manual/html_node/Invoking-guix-gc.html

[1] For example:
http://git.savannah.gnu.org/cgit/guix.git/commit/?id=d404a6f9711c8dcc1cc6cf55d8c07901aa450192