Re: Adding Substitute Mirrors page to installer

[raid5atemyhomework]

bump

> bump
>
> > Hello Mathieu,
> >
> > > Hello,
> > > Thanks for this patch, it seems to work fine!
> > >
> > > > -               ;; Extract the substitute URLs of the user 
> > > > configuration.
> > > >
> > > >
> > > > -               (os              (read-operating-system 
> > > > (%installer-configuration-file)))
> > > >
> > > >
> > > > -               (substitute-urls (and=> (find
> > > >
> > > >
> > > > -                                         (lambda (service)
> > > >
> > > >
> > > > -                                           (eq? guix-service-type
> > > >
> > > >
> > > > -                                                (service-kind 
> > > > service)))
> > > >
> > > >
> > > > -                                         (operating-system-services 
> > > > os))
> > > >
> > > >
> > > > -                                       (compose 
> > > > guix-configuration-substitute-urls
> > > >
> > > >
> > > > -                                                service-value)))
> > > >
> > > >
> > >
> > > We could make the mirror selection a proper step, adding it to (gnu
> > > installer record). Then in (gnu installer), you could add:
> > > --8<---------------cut here---------------start------------->8---
> > > (installer-step
> > > (id 'mirrors)
> > > (description (G_ "Mirror substitute server"))
> > > (compute (lambda _
> > > ((installer-mirrors-page current-installer)))))
> > > --8<---------------cut here---------------end--------------->8---
> > > This way, you should be able to select the step result in
> > > "run-final-page" this way:
> > > --8<---------------cut here---------------start------------->8---
> > > (let* ((configuration (format-configuration prev-steps result))
> > > (user-partitions (result-step result 'partition))
> > > (locale (result-step result 'locale))
> > > (users (result-step result 'user))
> > > (mirrors (result-step result 'mirrors))
> > > (install-ok?
> > > (with-mounted-partitions
> > > user-partitions
> > > (configuration->file configuration)
> > >
> > >          (run-config-display-page #:locale locale)
> > >          (run-install-shell locale #:users users #:mirrors mirrors))))
> > >
> > >
> > > ...)
> > > --8<---------------cut here---------------end--------------->8---
> > > That would avoid the need to parse the resulting configuration file.
> >
> > I don't think that will work.
> > The intent is that mirror selection affects two things:
> >
> > -   The actual installed system, i.e. `/etc/config.scm`.
> >
> > -   The installer's Guix Daemon.
> >     If my understanding of the above is correct, it will only affect the 
> > installer's Guix Daemon (via `run-install-shell` which will call into 
> > `install-system`, presumably with the added argument), but not affect the 
> > installed system, because the `configuration` cannot be modified by the 
> > `'mirrors` page in the above construction.
> >     Currently what the installer assumes is that a page will at most 
> > include a unique entry into the `operating-system`, but it cannot handle a 
> > page which modifies the entry created by a previous page.
> >     It would be a breakage of expectations to ask the user to select some 
> > mirror, then the installed system, when `guix system reconfigure`d, uses 
> > the default `ci.guix.gnu.org`.
> >     My patch affects both, because that is logically what a user would 
> > expect, after all, they selected a particular server to install from.
> >     Thus, they expect, that both the installed system, and the installer, 
> > will use the selected mirror.
> >     Of course, it feels somewhat dirty, as there is a need to read the 
> > configuration file.
> >     It would be cleaner if a page could affect the field created by a 
> > previous page.
> >     For example, perhaps the result of a page is not an AST that is a field 
> > of an `operating-system` form, but instead a procedure that accepts a 
> > `(operating-system ...)` form and returns it.
> >     Most existing pages would just append their keyed sub-form.
> >     However the `mirrors` page would modify an existing `services` field in 
> > the input `operating-system` form instead.
> >
> >
> > > > +(define (run-substitute-mirror-page)
> > > >
> > > > -   (let ((title (G_ "Substitute mirror")))
> > > >
> > > > -   (run-listbox-selection-page
> > > >
> > > > -            #:title title
> > > >
> > > >
> > > > -            #:info-text (G_ "Choose a server to get substitutes from.
> > > >
> > > >
> > > > -
> > > >
> > > > +Depending on your location, the official substitutes server can be 
> > > > slow; \
> > > > +in that case, using a mirror may be faster.")
> > >
> > > I wonder if it would make sense to select multiple mirrors, as fallback
> > > if the preferred mirror is not up to date. We could also add the
> > > possibility for the user to add a mirror manually.
> > > In that case, the mirror page could look like the "User creation" page,
> > > with an "Add" button opening a popup proposing to type a mirror URL or
> > > to select one from an existing list.
> > > WDYT?
> >
> > I think Less is More, and deploying an installer with a simple "select one 
> > mirror" pagenow will cover 90% of use-cases, and we can add the more 
> > complicated page later when there is more time.
> > In particular, there is really only one public mirror of Guix that I know 
> > of, the SJTU mirror, so all the flexibility here is not very useful, at 
> > least not to me.
> > Since "multiple mirrors" aren't even available yet anyway, why add the 
> > complication now?
> > Maybe you can encourage more people to actually run mirrors if the 
> > installer has a visible "select mirrors" page, so that you can actually get 
> > more than just the SJTU mirror and "select multiple mirrors" is now a 
> > (good) problem to have to solve.
> > For now I think a simple "select one mirror, we'll add ci.guix.gnu.org as a 
> > fallback" would be better.
> > You can add a "select multiple mirrors in an order I want to specify" 
> > later, when there are multiple mirrors existing.
> > Thanks
> > raid5atemyhomework