Yes, the cups
plug should also work with no CUPS Snap installed. It should work the same way as cups-control
, being implicit on classic systems. From the Snap Store auto-connection side cups
should auto-connect by default and cups-control
should only auto-connect if the Snap Store team has approved the Snap requesting this. Existing Snaps which plug cups-control
for the sole sake of printing should switch to cups
.
Your slots-per-plug: *
idea should even work, as the client app will connect to CUPS through the standard resources, /run/cups/cups.sock
and localhost:631
. If only the CUPS Snap is installed, these resources are used by the CUPS Snap, if a classic CUPS is installed, independent whether there is the CUPS Snap in addition, these resources lead to the classic CUPS. So if the app plugs both slots, the communication always goes to the correct, expected CUPS. And both CUPS are protected against administrative tasks from fully confined Snaps plugging only cups
.
So let us go the slots-per-plug: *
way. Do I have to change something in the CUPS Snap for that and if yes, tell me what. And tell me if I have to change it immediately or wait for some change in snapd or so.