cups service: fix client sockets

Use systemd to create the directory for UNIX socket. Also use localhost instead
of 127.0.0.1 as is done in default cupsd.conf so that IPv6 is enabled when
available.

2 files changed, 8 insertions, 3 deletions

diff --git a/nixos/modules/services/printing/cupsd.nix b/nixos/modules/services/printing/cupsd.nix
index 4c7f58d1d8b..ecab8cfc7df 100644
--- a/nixos/modules/services/printing/cupsd.nix
+++ b/nixos/modules/services/printing/cupsd.nix
@@ -124,7 +124,7 @@ in
 
       listenAddresses = mkOption {
         type = types.listOf types.str;
-        default = [ "127.0.0.1:631" ];
+        default = [ "localhost:631" ];
         example = [ "*:631" ];
         description = ''
           A list of addresses and ports on which to listen.
@@ -321,7 +321,10 @@ in
             ''}
           '';
 
-          serviceConfig.PrivateTmp = true;
+          serviceConfig = {
+            PrivateTmp = true;
+            RuntimeDirectory = [ "cups" ];
+          };
       };
 
     systemd.services.cups-browsed = mkIf avahiEnabled
diff --git a/nixos/tests/printing.nix b/nixos/tests/printing.nix
index 2d3ecaf94cf..98900883061 100644
--- a/nixos/tests/printing.nix
+++ b/nixos/tests/printing.nix
@@ -39,7 +39,9 @@ import ./make-test.nix ({pkgs, ... }: {
       $client->waitForUnit("cups.service");
       $client->sleep(10); # wait until cups is fully initialized
       $client->succeed("lpstat -r") =~ /scheduler is running/ or die;
-      $client->succeed("lpstat -H") =~ "localhost:631" or die;
+      # Test that UNIX socket is used for connections.
+      $client->succeed("lpstat -H") =~ "/var/run/cups/cups.sock" or die;
+      # Test that HTTP server is available too.
       $client->succeed("curl --fail http://localhost:631/");
       $client->succeed("curl --fail http://server:631/");
       $server->fail("curl --fail --connect-timeout 2  http://client:631/");