bug#61570: Backward incompatible changes in mpd-service-type

[Liliana Marie Prikler <liliana.prikler@gmail.com>]

Hi Bruno and Maxim,

Am Freitag, dem 17.02.2023 um 15:33 +0000 schrieb Bruno Victal:
> > 2.  The MPD user appears to be created instead of using an existing
> > one.  I was using my own account, like this:
> > 
> > --8<---------------cut here---------------start------------->8---
> >       (service mpd-service-type
> >                (mpd-configuration
> >                 (user "maxim")
> >                 (address "0.0.0.0")
> >                 (outputs
> >                  (list (mpd-output)
> >                        (mpd-output
> >                         (name "streaming")
> >                         (type "httpd")
> >                         (mixer-type "none")
> >                         (extra-options
> >                          `((encoder . "lame")
> >                            (port    . "6601")
> >                            (bitrate . "320"))))))))
> > --8<---------------cut here---------------end--------------->8---
> > 
> > and 'guix system reconfigure' is now warning that a user is defined
> > twice, [...]
> 
> This is an unfortunate situation arising from a bug before the
> service was refactored.
> Before d7fd9ec209f72e9cfff04a48bf16e092f258d8ff (actually
> 5c5f0fc1135ff15f9c4adfc5f27eadd9a592b5d1)
> mpd-service-type contained a service-extension for %mpd-accounts
> where the values for both group and user were hardcoded to "mpd"
> but this was actually never used since shepherd would launch the
> service using root and mpd would downgrade its permissions and switch
> to the user specified in the mpd-configuration record since this
> field is serialized to the configuration file.
It would be quite weird if someone had already pointed out how to
properly handle the accounts and groups only for that to be ignored
later in the review.

Am Samstag, dem 24.12.2022 um 18:20 +0100 schrieb eine leichtsinnige
Person, die ihre eigenen Anmerkungen vergisst:
> I think you should make it so that you can pass a user-account and
> user-group to the mpd service so that they can be reused (with a
> sanitizer that creates a user/group from string).
Never mind then.


Am Freitag, dem 17.02.2023 um 07:53 -0500 schrieb Maxim Cournoyer:
> Else an error rather than a warning when multiple same-name users are
> defined would be more appropriate, I think.
Guess what, it used to be a formatted message (i.e. an actual error). 
However, that broke some configs as reported in [1], so I demoted it to
a warning.

Cheers

[1] http://git.savannah.gnu.org/cgit/guix.git/commit/?id=8488f45b6e05d646224cc2b410497ddf9864c612