Re: Modify system behavior after reconfigure

[Andreas Enge <andreas@enge.fr>]

On Sat, Mar 17, 2018 at 04:06:35PM +0300, Jone wrote:
> Ricardo writes:
> > Reconfiguring does not take a lot of time when there have been only
> > minor changes.  It only takes a couple of seconds.
> Well, let's just say, this is not always true. The last time was a full
> compilation of Icecat from source (!) "It only takes a couple of
> hours" ;) 

Ricardo is right if you do not make other, *unrelated* changes - of course
updating icecat may trigger a rebuild of icecat.

So in the case of only changing some configuration items, one would need
to make sure to use the exact same copy of guix as for the previous
configuration. Either one should not do a "guix pull" in between, or one
can keep a git checkout on the same branch or commit and do a
"./pre-inst-env guix system reconfigure...".

Then updating everything can be done at a separate occasion (over night,
for instance, or after icecat has been built on the substitute server).

Also, this problem can be circumvented by not having packages in the *system*
definition, but only in *user* profiles. This decouples updates of single
packages from updates of the system configuration.

Andreas