Re: How to roll back a "guix system reconfigure"?

[Alex Kost <alezost@gmail.com>]

Chris Marusich (2016-04-02 22:20 +0300) wrote:

> Hi,
>
> After running a "guix system reconfigure", it is possible to boot to a
> previous version of the system by manually selecting it from the GRUB
> menu.  However, if you want to permanently roll back to a previous
> version (e.g., because something broke), it's a nuisance to do this
> every time you boot.  Of course, assuming guix is still working after
> the reconfigure, you could simply do another "guix system reconfigure"
> using the previous version of your operating system configuration file,
> but it seems like that shouldn't be necessary.
>
> What is the recommended way to roll back after a "guix system
> reconfigure"?  Is it sufficient to manually edit the grub.cfg file to
> remove all mention of the generations after the one to which you want to
> roll back?  If you do that, will the gc root(s) associated with the bad
> configuration stay around forever?  Would it make sense to add a command
> like "guix system roll-back" or "guix system switch-generation", similar
> to "guix package --roll-back" and "guix package --switch-generation"?

Yes, I think these things will be added eventually.  It's just that no
one has not been interested enough in these features yet to add them.

Currently there are 2 ways to perform a system roll-back:

1. Manually: system generations are just symlinks in "/var/guix/profiles"
directory, so you can change "/var/guix/profiles/system" link to point
to any previous generation.

2. Using Emacs interface (you have to run emacs as root):

 - M-x guix-system-generations;
 - Press "c" on a generation you want to make current.

-- 
Alex