bug#31907: New users get wrong/old profile path to guix after reconfiguring

[Dan Partelly]

Well, I wondered myself , and I was palning to test when I arrive home today.

But here is my take:

1. Premise: The system configuration is declarative. The declarative state 
should be obeyed all times by the system
2. Implication: running a guix pull (or any other form of update) as any user 
should not do anything to the guix stored in the system profile
3. Implication: updates of binaries in the system profile should never be  
triggered by anything else than a guix reconfigure
4. Implication  creating a new user should result in him seeing the base state 
of the system , as left by guix reconfigure . It should never see any version 
installed by any other user , root included.

Now the issues:

- Although the system is declarative, once you run guix config / guys 
reconfigure you do not know the whole state of the system. Arbitrary package 
versions are installed, and reconfigure will arbitrary update those packages
- the only way I seen to have consistent state is to lock all system packages 
to a known version, and reconfigure should obey the lock.
-running guix reconfigure is an  issue at the current time.  It is because 
unless you lock each  package @version (and I did not tried t see if this works 
, a developer should confirm, or point to some good workarround) adding a user, 
changing system configuration in some othe small way 
  seems to trigger a rebuild
- there is no guarantee that GuixSD will offer you a substitution instead of 
building the derivation. Which if you are unfortunate to update a package for 
which is not prebuilt substitution you will end up looking at compiles wearing 
out your time. 
-it may cause rebuild of critical system daemons, then, guess what, stop them 
and reload. You have to be very careful and run dry builds to see if anyone 
touches your system services, cause you do not want unplanned service outage on 
a server. 
-it reports success even if it fails to bring the system in the required state. 
For example for me reconfigure failed to restart 2 services it stopped, but it 
happily reported all went ok 
- guix is still broken for me: reconfiguring the system results in build errors 
sometimes. Also results in service errors , like home service not being able to 
be restarted. 
- guix pull  inflicts all the wrongs of the universe upon its users. No 
critical system utility should ever update itself from the bleeding edge of a 
source repository. No matter how genius the developer is, it will always break 
in too many ways. This is very bad practice.
- guix reconfigure without locked packages does the same offense. will try to 
update to a version of itself derived directly from development. 

Tools:
  
-  guix still lacks the tools to make sense as a user of what is happening. For 
example, a guix diff which gives insight what exactly triggered a rebuild. I 
could not find such a thing. 
-  other tools to keep under control the rebuilding happiness. I have better 
things to do on my system then looking at walls of compiling , donno for 
others. I want to add a user , not trigger compiles :P





> On Jun 26, 2018, at 14:06, address@hidden wrote:
> 
> ou could ask: why care about the guix version in the system
> profile at all? It is not used as soon as you run guix pull or populated
> the .config/guix some other way and adjusted the this to preceede in the
> PATH.
> <sdb> I care because if I create a new user via config.scm they by
> default get access to an outdated guix when a newer is available. This
> is in my view a bug.