Emmanuel Medernach <emmanuel.medernach@gmail.com> writes:

> Hello Guixers !
>
> I  created an  image with  'guix system  vm-image'
> which  contains  local  defined  packages.   These
> packages  are  present   on  the  Virtual  Machine
> however  they are  not listed  with 'guix  package
> --list-installed'.

'guix package -I' only lists packages that are installed to the user
profile.  Use 'guix package -p /run/current-system/profile -I' to see
system-installed packages.

> As  I   need  to   customize
> LD_LIBRARY_PATH, I use "guix  build" to list store
> directories  from  package   names  but  it  tries
> instead to  recompile them  even though  they  are
> already installed.

The reason 'guix build foo' gives a different result is because you have
not run 'guix pull', so you are using the "guix snapshot" from
gnu/packages/package-management.scm, which is on a fixed commit.

Whereas when you built the VM, you were likely using a newer version of
Guix.

> How to  properly export  local definitions  in the
> virtual machine image ?

There are a couple of ways around this.  One is to run 'make
update-guix-package' in the Guix source tree to update the Guix
snapshot, and use './pre-inst-env' when generating the VM.  It requires
a Guix development setup though.

Another is to look at the commit that was used to generate the VM in
/run/current-system/provenance and run 'guix pull --commit=that-commit'.

Perhaps 'guix system vm-image' could learn a '--update-guix-snapshot' to
automatically update the "system guix".  Someone would have to implement
it first though.  :-)

HTH,
Marius