Re: bug#26608: channels.scm supporting substitutes

[zimoun <zimon.toutoune@gmail.com>]

On Wed, 4 Dec 2019 at 15:56, Nome Grey <greynome72@gmail.com> wrote:

> Thanks.  The problem is that old substitutes are not used on new guix pulls, so upgrading takes unworkably long.  Pulling to the right commit, as partly described in the bug reports, can make many more substitutes work, and has helped me a lot.

I am not sure it works the way you describe.

From my understanding, when you use "guix install foo", Guix computes
a derivation and query the substitutes. If the derivation exists on
the server, it downloads. It does not matter so much from which Guix
version you run "guix install". On the contrary, too recent version
(new "guix pull") should not be built by Cuirass yet and so served as
substitute.

What is the output of the command: "guix install ungoogled-chromium
--dry-run" on your machine?

If it does not do the job, you can try: "guix install
ungoogled-chromium --substitute-urls=http://berlin.guixsd.org". Does
it fail? What is the output of the command?


( I think that http://berlin.guixsd.org and https://ci.guix.gnu.org
point to the same build farm.)


>> >> I am currently running guix aca2bf5 but have a long-running process to downgrade to 1b6c5e8 in order to find a substitute for ungoogled-chromium 78
>>
>> To see if the substitute is available or not, the command "guix
>> weather" fits your need [2].
>>
>> [2] https://guix.gnu.org/manual/en/html_node/Invoking-guix-weather.html#Invoking-guix-weather
>>
>>
>> However, the package ungoogled-chromium 78 is not available for the
>> system i686. You probably need to build it yourself (ressource
>> consuming) with "guix build ungoogled-chromium".
>
>
> I'm pretty sure I found just recently a successful build of ungoogled-chromium-78 for i686-linux: http://berlin.guixsd.org/build/1979882/details .  What do you think?

You can also try: "guix build ungoogled-chromium --dry-run" to see
what Guix will download and what it will build locally.


I am not sure... but it is not because you find the webpage of a
successful build of the package ungoogled-chromium-78 for i686-linux
that it means the substitutes is available; even if this one is
available. ;-)

http://ci.guix.gnu.org/build/1979882/details


>> I am not sure that channel will help to fetch the result of any build.
>> Channel helps to add more recipes about how to build packages. And I
>> am not aware of other public substitutes server than
>> https://ci.guix.gnu.org.
>
>
> By only upgrading to releases with substitutes available, fewer builds are required on the local system, which can still be occasionally brought up to date.  The user channel filters the official channel, to hide releases without substitutes built yet.

I am not sure it works as you think.


I am checking why Guix claims the substitute is not available for i686
when it really is.


All the best,
simon