[bug#45957] [PATCH] * doc/guix-cookbook.texi (Guix System Image API): new section

[Mathieu Othacehe]

Hello Joshua,

Thanks for this new revision! It's really nice to follow your live
coding sessions. I think it can be very valuable for newcomers willing
to dive into Guix internals.

> +This record also contains the operating-system to instantiate. The
> +@code{format} field defines the image type and can be @code{disk-image},
                                                                   ^
                                                                   efi-raw
> +@code{compressed-qcow2} or @code{iso9660}. In the future, it could be
              ^
              qcow2
              
The supported image types list is now longer, so you could add "for
instance". We could also specify that "raw" designates disk-image that
can be copied as is on the installation media.

> +@file{gnu/guix/guix-src/gnu/system/images/novena.scm}

You mean @file{gnu/system/images/novena.scm}, right?

> +   - pinebook-pro-raw
> +   - pine64-raw
> +   - novena-raw
> +   - hurd-raw
> +   - hurd-qcow2
> +   - qcow2
> +   - uncompressed-iso9660
> +   - raw
> +   - arm64-raw
> +   - arm32-raw
> +   - iso9660

Since recently "raw" has been renamed "efi-raw".

> +@lisp
> +(use-modules
> + (srfi srfi-9)
> + (srfi srfi-9 gnu)
> + (gnu services linux)
> + (gnu system images pine64))
> +
> +(define my-pine64-barebones-os
> +  (set-fields pine64-barebones-os
> +              ((operating-system-timezone) "America/Indiana/Indianapolis")
> +              ((operating-system-user-services)
> +               (cons*
> +                (service earlyoom-service-type
> +                         (earlyoom-configuration
> +                          (prefer-regexp "icecat|chromium|firefox")))
> +                (operating-system-user-services pine64-barebones-os)))))

Nice example. However, we generally prefer using inheritance. That would
give:

--8<---------------cut here---------------start------------->8---
(use-modules (gnu system)
             (gnu services linux)
             (gnu system images pine64))

(let ((base-os pine64-barebones-os))
  (operating-system
    (inherit base-os)
    (timezone "America/Indiana/Indianapolis")
    (services
     (cons*
      (service earlyoom-service-type
               (earlyoom-configuration
                (prefer-regexp "icecat|chromium|firefox")))
      (operating-system-user-services base-os)))))
--8<---------------cut here---------------end--------------->8---

WDYT?

Thanks,

Mathieu