Re: shepherd GEXP module import mystery

[Attila Lendvai <attila@lendvai.name>]

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hi Felix, Ludo,


> > a start GEXP of my service sees bindings that come from the module
> > called (shepherd support), but i have no idea who and where imports
> > that module.
> 
> 
> Without code it's hazardous to speculate, but could the Guix service
> (gnu service mcron) cause that issue when it is being logged?


unfortunately it's a complex web of stuff, but i managed to make a small reproducer that is attaced.

it can be run with:

$(guix system --no-graphic vm reproducer.scm)

and in the VM (must use fold, because it's a dumb terminal):

cat /var/log/messages | fold -150

to my surprise this one does list (shepherd support) in the module-use list. and i realized why: the logging infrastructure somewhere siently truncates the lines, and in my original case that module was chopped off.

not that i understand everything here... e.g. why are there several (guix build utils) modules?

*** reproducer gexp speaking, current module: #<module (#{g107}#) 7f5b49cf61e0>,
module-uses: (
#<interface (guile) 7f5b4b652dc0>
#<interface (oop goops) 7f5b4a256c80>
#<interface (shepherd service) 7f5b49cf3c80>
#<interface (srfi srfi-34)
#<interface (system repl error-handling) 7f5b49d9ab40> #<custom-interface (guix build utils) 7f5b49d9a140>
#<interface (guix build syscalls) 7f5b49495e60> #<custom-interface (guix build utils) 7f5b49495500> #<custom-interface (gnu build file-systems) 7f5b49523460>
#<interface (gnu system file-systems) 7f5b494deb40>
#<custom-interface (guix build utils) 7f5b495233c0>
#<custom-interface (gnu build file-systems) 7f5b49523320>
#<custom-interface (guix build utils) 7f5b49523280>
#<custom-interface (gnu build file-systems) 7f5b495231e0>
#<custom-interface (guix build utils) 7f5b49523140>
#<custom-interface (gnu build file-systems) 7f5b495230a0>
#<custom-interface (guix build utils) 7f5b49523000>
#<custom-interface (guix build utils) 7f5b4954df00>
#<custom-interface (guix build utils) 7f5b4954de60>
#<custom-interface (guix build utils) 7f5b4954ddc0>
#<interface (gnu build activation) 7f5b4954db40>
#<interface (gnu system accounts) 7f5b4954d8c0>
#<custom-interface (guix build utils) 7f5b4b5e6000>
#<custom-interface (guix build utils) 7f5b49453f00>
#<interface (gnu build linux-boot) 7f5b4b5e6e60>
#<custom-interface (guix build utils) 7f5b49453e60>
#<interface (ice-9 popen) 7f5b49453be0>
#<interface (ice-9 rdelim) 7f5b4a210f00>
#<interface (ice-9 match) 7f5b4b652460>
#<custom-interface (guix build utils) 7f5b49453b40>
#<interface (srfi srfi-1) 7f5b4b692320>
#<interface (gnu build shepherd) 7f5b494538c0>
#<interface (rnrs bytevectors) 7f5b4b6def00>
#<interface (rnrs io ports) 7f5b49d18dc0>
#<custom-interface (guix build utils) 7f5b49453140>
#<custom-interface (guix build utils) 7f5b494530a0>
#<custom-interface (guix build utils) 7f5b49453000>
#<custom-interface (guix build utils) 7f5b497f6f00>
#<custom-interface (guix build utils) 7f5b497f6e60>
#<custom-interface (guix build utils) 7f5b497f6dc0>
#<custom-interface (guix build utils) 7f5b497f6d20>
#<custom-interface (guix build utils) 7f5b497f6c80>
#<custom-interface (guix build utils) 7f5b497f6be0>
#<custom-interface (guix build utils) 7f5b497f6b40>
#<custom-interface (guix build utils) 7f5b497f6aa0>
#<custom-interface (guix build utils) 7f5b497f6a00>
#<custom-interface (guix build utils) 7f5b497f6960>
#<custom-interface (guix build utils) 7f5b497f68c0>
#<custom-interface (guix build utils) 7f5b497f6820>
#<custom-interface (guix build utils) 7f5b497f6780>
#<custom-interface (guix build utils) 7f5b497f66e0>
#<interface (srfi srfi-26) 7f5b4a64ff00>
#<custom-interface (shepherd support) 7f5b497f6640>
#<custom-interface (guix build utils) 7f5b497f65a0>
#<interface (ip addr) 7f5b497f6280>
#<interface (ip link) 7f5b497f6000>
#<interface (ip route) 7f5b49772820>
#<interface (ice-9 format) 7f5b4b7b86e0>),
ringbuffer: #<procedure ring-buffer (size)>


so, the only mystery left is that i still don't know where it is imported into the unnamed package in which the GEXPs are compiled/loaded, and whether that is intended.

maybe it's part of the shepherd API that (shepherd support) is made available for the service GEXPs? looking at the public definitions in (shepherd support), it's not obvious that those are meant to be available for the users of shepherd, though.

Ludo?


> In my code tree, which is a month behind, (gnu services mcron) is the
> only Guix service that imports (shepherd support).


it's a good hint, but that could only cause this if all the service GEXPs were loaded into the same module, but that would have already broken things in countless other ways.

-- 
• attila lendvai
• PGP: 963F 5D5F 45C7 DFCD 0A39
--
“We are products of our past, but we don't have to be prisoners of it.”
	— Rick Warren (1954–)

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: reproducer.scm --]
[-- Type: text/x-scheme; name=reproducer.scm, Size: 1528 bytes --]

;; Run with something like this:
;; $(guix system --no-graphic vm reproducer.scm)

(define-module (reproducer)
  #:use-module (gnu system)
  #:use-module (gnu system shadow)
  #:use-module (gnu system nss)
  #:use-module (gnu system vm)
  #:use-module (gnu tests)
  #:use-module (gnu services)
  #:use-module (gnu services base)
  #:use-module (gnu services dbus)
  #:use-module (gnu services shepherd)
  #:use-module (gnu packages admin)
  #:use-module (gnu packages base)
  #:use-module (gnu packages bash)
  #:use-module (gnu packages certs)
  #:use-module (gnu packages package-management)
  #:use-module (gnu packages linux)
  #:use-module (guix gexp)
  #:use-module (guix git)
  #:use-module (guix git-download)
  #:use-module (guix store)
  #:use-module (guix modules)
  #:use-module (guix packages)
  #:use-module (srfi srfi-1)
  #:use-module (ice-9 match))

(operating-system
  (inherit %simple-os)
  (services
   (cons*
    (simple-service
     'reproducer
     shepherd-root-service-type
     (list
      (shepherd-service
       (requirement '(file-systems))
       (provision '(reproducer))
       (documentation "")
       (start
        #~(begin
            (lambda _
              (format #t "*** reproducer gexp speaking, \
current module: ~A, \
module-uses: ~A, \
ringbuffer: ~A~%"
                      (current-module)
                      (module-uses (current-module))
                      (and=> (module-variable (current-module) 'ring-buffer) variable-ref))
              0))))))
    %base-services)))