Merge pull request #65040 from matthewbauer/cups-fixes

nixos/cups fixes

nixos/doc/manual/release-notes/rl-1909.xml

@@ -254,6 +254,15 @@
        If IBus support in Qt 4.x applications is required, add the <literal>ibus-qt</literal> package to your <xref linkend="opt-environment.systemPackages" /> manually.
      </para>
    </listitem>
+   <listitem>
+     <para>
+       The CUPS Printing service now uses socket-based activation by
+       default, only starting when needed. The previous behavior can
+       be restored by setting
+       <option>services.cups.startWhenNeeded</option> to
+       <literal>false</literal>.
+     </para>
+   </listitem>
   </itemizedlist>
  </section>
 

nixos/modules/services/printing/cupsd.nix

@@ -127,7 +127,7 @@ in
 
       startWhenNeeded = mkOption {
         type = types.bool;
-        default = false;
+        default = true;
         description = ''
           If set, CUPS is socket-activated; that is,
           instead of having it permanently running as a daemon,
@@ -296,11 +296,16 @@ in
     # gets loaded, and then cups cannot access the printers.
     boot.blacklistedKernelModules = [ "usblp" ];
 
+    # Some programs like print-manager rely on this value to get
+    # printer test pages.
+    environment.sessionVariables.CUPS_DATADIR = "${bindir}/share/cups";
+
     systemd.packages = [ cups.out ];
 
     systemd.sockets.cups = mkIf cfg.startWhenNeeded {
       wantedBy = [ "sockets.target" ];
-      listenStreams = map (x: replaceStrings ["localhost"] ["127.0.0.1"] (removePrefix "*:" x)) cfg.listenAddresses;
+      listenStreams = [ "/run/cups/cups.sock" ]
+        ++ map (x: replaceStrings ["localhost"] ["127.0.0.1"] (removePrefix "*:" x)) cfg.listenAddresses;
     };
 
     systemd.services.cups =
@@ -362,10 +367,10 @@ in
       { description = "CUPS Remote Printer Discovery";
 
         wantedBy = [ "multi-user.target" ];
-        wants = [ "cups.service" "avahi-daemon.service" ];
-        bindsTo = [ "cups.service" "avahi-daemon.service" ];
-        partOf = [ "cups.service" "avahi-daemon.service" ];
-        after = [ "cups.service" "avahi-daemon.service" ];
+        wants = [ "avahi-daemon.service" ] ++ optional (!cfg.startWhenNeeded) "cups.service";
+        bindsTo = [ "avahi-daemon.service" ] ++ optional (!cfg.startWhenNeeded) "cups.service";
+        partOf = [ "avahi-daemon.service" ] ++ optional (!cfg.startWhenNeeded) "cups.service";
+        after = [ "avahi-daemon.service" ] ++ optional (!cfg.startWhenNeeded) "cups.service";
 
         path = [ cups ];
 
@@ -421,4 +426,7 @@ in
     security.pam.services.cups = {};
 
   };
+
+  meta.maintainers = with lib.maintainers; [ matthewbauer ];
+
 }

nixos/tests/printing.nix

@@ -3,7 +3,7 @@
 import ./make-test.nix ({pkgs, ... }: {
   name = "printing";
   meta = with pkgs.stdenv.lib.maintainers; {
-    maintainers = [ domenkozar eelco ];
+    maintainers = [ domenkozar eelco matthewbauer ];
   };
 
   nodes = {
@@ -34,10 +34,6 @@ import ./make-test.nix ({pkgs, ... }: {
     ''
       startAll;
 
-      # Make sure that cups is up on both sides.
-      $server->waitForUnit("cups.service");
-      $client->waitForUnit("cups.service");
-      $client->sleep(10); # wait until cups is fully initialized
       $client->succeed("lpstat -r") =~ /scheduler is running/ or die;
       # check local encrypted connections work without error
       $client->succeed("lpstat -E -r") =~ /scheduler is running/ or die;

pkgs/misc/cups/default.nix

@@ -133,7 +133,7 @@ stdenv.mkDerivation rec {
     homepage = https://cups.org/;
     description = "A standards-based printing system for UNIX";
     license = licenses.gpl2; # actually LGPL for the library and GPL for the rest
-    maintainers = with maintainers; [ ];
+    maintainers = with maintainers; [ matthewbauer ];
     platforms = platforms.unix;
   };
 }