roles/printserver: add option for ServerName

roles/printserver.nix

@@ -40,6 +40,13 @@ in
       ];
     };
 
+    serverName = mkOption {
+      type = types.str;
+      default = "localhost";
+      description = "Name of server to indicate to CUPS";
+      example = "print.example.com";
+    };
+
     serverAliases = mkOption {
       type = types.listOf types.str;
       default = [ ];
@@ -89,6 +96,7 @@ in
           Listen 0.0.0.0:631
           BrowseLocalProtocols dnssd
 
+          ServerName ${cfg.serverName}
           ${lib.optionalString (cfg.serverAliases != [ ]) serverAliasesText}
 
           DefaultAuthType Basic