dnf versus yum

[Matthew Miller]

On Wed, Jan 08, 2014 at 01:43:01PM -0500, Przemek Klosowski wrote:
> >hence that is why whatever calls itself a replacement for yum should *not*
> >support destroy the running system without whatever *force switch*
> I don't like the weird partial functionality of this feature. It is
> apparently undocumented---actually, it'd be tricky to document it
> because it seems to protect some nebulous set of system facilities
> (running kernel, current yum, presumably RPM and runtime libraries;
> probably also grub; what else?).

I'm a little lost in the thread, but do you mean that yum's protected
packages functionality is undocumented? If that is what you mean, check the
man page. It says:

  protected_packages  This  is  a list of packages that yum should
  never completely remove. They are  protected  via  Obsoletes  as
  well as user/plugin removals.

  The  default  is:  yum  glob:/etc/yum/protected.d/*.conf  So any
  packages which should be protected can do so by including a file
  in /etc/yum/protected.d with their package name in it.

  Also  if  this  configuration  is set to anything, then yum will
  protect the package corresponding to the running version of  the
  kernel.

And on _my_ system, there's a /etc/yum/protected.d/systemd.conf containing
owned by "systemd" and a gnome.conf containing gnome-shell which I think I
put there myself. (Nothing owns it and I don't remember.)

This goes an amazingly long way toward protecting the system from accidental
autophagy without really being all that complex.


> Another point:  it shouldn't be hardwired into the package manager
> but rather result from package properties. I can see several ways to
> do it:
>  - an 'essentiality' property in the RPM file
>  - a yum/dnf configuration file specifying a set of protected packages
>  - a special, unremovable 'system' package that depends on kernel and dnf

Option #2 it is.

> Last two would be preferable, because they allow tailoring the set
> of protected packages differently for a datacenter server vs. a
> network appliance, desktop, etc.

Exactly. And configuration is better than a magic package.

-- 
Matthew Miller    --   Fedora Project    --    <mattdm at fedoraproject.org>