Bug#847442: gnome-software says 'Failed to obtain authentication.'

[Simon McVittie]

On Sat, 23 May 2020 at 21:55:26 -0500, Stephen Paul Weber wrote:
> After installing `gnome-software` when I try 
> to install anything it does not prompt for password and simply says "you do not 
> have permission to install software".
> 
> I am not running under a full GNOME environment, but nevertheless policykit and 
> packagekit and dbus are running, if that is relevant.

You also need to be running a polkit "agent", which is the UI component
that prompts for a password. In Debian this is represented by the
polkit-1-auth-agent virtual package.

In the full GNOME desktop (which is what GNOME Software is primarily
designed for), the agent is part of GNOME Shell itself. Other full desktop
environments should either have a built-in polkit agent, or depend on one
that is a separate process and start it during session startup. If you
are building your own desktop environment from individual packages,
and you want to be able to authenticate for privileged actions, then
you'll need to include a polkit agent.

Other desktops' polkit agents include include polkit-kde-agent-1,
lxpolkit, lxqt-policykit, mate-polkit, ukui-polkit and policykit-1-gnome.
policykit-1-gnome is the GNOME 2 implementation, which is no longer used
in GNOME itself, and I suspect it's essentially unmaintained; but it's
still used in Cinnamon, XFCE and I think also Unity.

It is not straightforward to make packages like gnome-software recommend
on a polkit agent, because the right implementation to prefer depends
on the desktop environment you are using: I suspect you would not want
it to have a Recommends on "gnome-shell | polkit-1-auth-agent", but pulling
in a less-maintained implementation like policykit-1-gnome would not be
appropriate for GNOME users.

    smcv