mcron service and PATH (was: Home service for mbsync?)

[Emmanuel Beffara]

Hello,

De Carlo Zancanaro le 22/02/2024 à 10:27:
> On Wed, Feb 21 2024, Felix Lechner via wrote:
> > Does anyone have an 'mbsync' home service, please? Thanks!
> 
> I just run mbsync as an mcron service. I have a custom script, because I
> do some weird stuff to update my mu index afterwards, but it shouldn't
> be hard to figure out how to call mbsync directly.
> 
> In my home services I have this:
> 
>    (simple-service 'mail-update-script
>                    home-mcron-service-type
>                    ;; Update email every five minutes.
>                    (list #~(job '(next-minute '(0 5 10 15 20 25 30 35 40 45 
> 50 55))
>                                 "/home/carlo/.local/bin/fetch-mail")))
> 
> Obviously this doesn't handle configuring mbsync, which I do outside of
> my home configuration.

I'm doing something similar, with a custom script that calls mbsync and does
some additional stuff for indexing and tagging by notmuch.

I recently noticed an issue with that: it seems that the command in the mcron
job is called with an incomplete PATH. I diagnosed that by creating a
similar mcron job with the command "/usr/bin/env > ~/E". Apparently my user
profile (as defined in .profile, which is managed by guix home) is indeed
inherited by the job, except for PATH which is reset and just contains
/run/current-system/profile/bin.

This is problematic if the job wants to call a command that is not in the
system profile. A workaround would be to define the job with an explicit
reference to a package, like:

     (service
       home-mcron-service-type
       (home-mcron-configuration
         (jobs (list
                 #~(job
                   '(next-minute (range 0 60 5))
                   (string-append #$isync "/bin/mbsync inbox")
                   )))))

but this does not completely solve the issue since PATH is still reset and
any command that is called through mbsync (e.g. through a PassCmd setting)
will fail if it does not have an absolute path.

Is there a proper way to inherit PATH from the user profile in mcron jobs ?

-- 
Emmanuel