{ config, lib, pkgs, ... }: with lib; let inherit (pkgs) cups cups-pk-helper cups-filters; cfg = config.services.printing; avahiEnabled = config.services.avahi.enable; polkitEnabled = config.security.polkit.enable; additionalBackends = pkgs.runCommand "additional-cups-backends" { } '' mkdir -p $out if [ ! -e ${cups.out}/lib/cups/backend/smb ]; then mkdir -p $out/lib/cups/backend ln -sv ${pkgs.samba}/bin/smbspool $out/lib/cups/backend/smb fi # Provide support for printing via HTTPS. if [ ! -e ${cups.out}/lib/cups/backend/https ]; then mkdir -p $out/lib/cups/backend ln -sv ${cups.out}/lib/cups/backend/ipp $out/lib/cups/backend/https fi ''; # Here we can enable additional backends, filters, etc. that are not # part of CUPS itself, e.g. the SMB backend is part of Samba. Since # we can't update ${cups.out}/lib/cups itself, we create a symlink tree # here and add the additional programs. The ServerBin directive in # cupsd.conf tells cupsd to use this tree. bindir = pkgs.buildEnv { name = "cups-progs"; paths = [ cups.out additionalBackends cups-filters pkgs.ghostscript ] ++ cfg.drivers; pathsToLink = [ "/lib" "/share/cups" "/bin" ]; postBuild = cfg.bindirCmds; ignoreCollisions = true; }; writeConf = name: text: pkgs.writeTextFile { inherit name text; destination = "/etc/cups/${name}"; }; cupsFilesFile = writeConf "cups-files.conf" '' SystemGroup root wheel ServerBin ${bindir}/lib/cups DataDir ${bindir}/share/cups DocumentRoot ${cups.out}/share/doc/cups AccessLog syslog ErrorLog syslog PageLog syslog TempDir ${cfg.tempDir} # User and group used to run external programs, including # those that actually send the job to the printer. Note that # Udev sets the group of printer devices to `lp', so we want # these programs to run as `lp' as well. User cups Group lp ${cfg.extraFilesConf} ''; cupsdFile = writeConf "cupsd.conf" '' ${concatMapStrings (addr: '' Listen ${addr} '') cfg.listenAddresses} Listen /var/run/cups/cups.sock SetEnv PATH /var/lib/cups/path/lib/cups/filter:/var/lib/cups/path/bin DefaultShared ${if cfg.defaultShared then "Yes" else "No"} Browsing ${if cfg.browsing then "Yes" else "No"} WebInterface ${if cfg.webInterface then "Yes" else "No"} LogLevel ${cfg.logLevel} ${cfg.extraConf} ''; browsedFile = writeConf "cups-browsed.conf" cfg.browsedConf; rootdir = pkgs.buildEnv { name = "cups-progs"; paths = [ cupsFilesFile cupsdFile (writeConf "client.conf" cfg.clientConf) (writeConf "snmp.conf" cfg.snmpConf) ] ++ optional avahiEnabled browsedFile ++ cfg.drivers; pathsToLink = [ "/etc/cups" ]; ignoreCollisions = true; }; filterGutenprint = pkgs: filter (pkg: pkg.meta.isGutenprint or false == true) pkgs; containsGutenprint = pkgs: length (filterGutenprint pkgs) > 0; getGutenprint = pkgs: head (filterGutenprint pkgs); in { ###### interface options = { services.printing = { enable = mkOption { type = types.bool; default = false; description = '' Whether to enable printing support through the CUPS daemon. ''; }; startWhenNeeded = mkOption { type = types.bool; default = false; description = '' If set, CUPS is socket-activated; that is, instead of having it permanently running as a daemon, systemd will start it on the first incoming connection. ''; }; listenAddresses = mkOption { type = types.listOf types.str; default = [ "localhost:631" ]; example = [ "*:631" ]; description = '' A list of addresses and ports on which to listen. ''; }; bindirCmds = mkOption { type = types.lines; internal = true; default = ""; description = '' Additional commands executed while creating the directory containing the CUPS server binaries. ''; }; defaultShared = mkOption { type = types.bool; default = false; description = '' Specifies whether local printers are shared by default. ''; }; browsing = mkOption { type = types.bool; default = false; description = '' Specifies whether shared printers are advertised. ''; }; webInterface = mkOption { type = types.bool; default = true; description = '' Specifies whether the web interface is enabled. ''; }; logLevel = mkOption { type = types.str; default = "info"; example = "debug"; description = '' Specifies the cupsd logging verbosity. ''; }; extraFilesConf = mkOption { type = types.lines; default = ""; description = '' Extra contents of the configuration file of the CUPS daemon (cups-files.conf). ''; }; extraConf = mkOption { type = types.lines; default = ""; example = '' BrowsePoll cups.example.com MaxCopies 42 ''; description = '' Extra contents of the configuration file of the CUPS daemon (cupsd.conf). ''; }; clientConf = mkOption { type = types.lines; default = ""; example = '' ServerName server.example.com Encryption Never ''; description = '' The contents of the client configuration. (client.conf) ''; }; browsedConf = mkOption { type = types.lines; default = ""; example = '' BrowsePoll cups.example.com ''; description = '' The contents of the configuration. file of the CUPS Browsed daemon (cups-browsed.conf) ''; }; snmpConf = mkOption { type = types.lines; default = '' Address @LOCAL ''; description = '' The contents of /etc/cups/snmp.conf. See "man cups-snmp.conf" for a complete description. ''; }; drivers = mkOption { type = types.listOf types.path; default = []; example = literalExample "with pkgs; [ gutenprint hplip splix cups-googlecloudprint ]"; description = '' CUPS drivers to use. Drivers provided by CUPS, cups-filters, Ghostscript and Samba are added unconditionally. If this list contains Gutenprint (i.e. a derivation with meta.isGutenprint = true) the PPD files in /var/lib/cups/ppd will be updated automatically to avoid errors due to incompatible versions. ''; }; tempDir = mkOption { type = types.path; default = "/tmp"; example = "/tmp/cups"; description = '' CUPSd temporary directory. ''; }; }; }; ###### implementation config = mkIf config.services.printing.enable { users.users = singleton { name = "cups"; uid = config.ids.uids.cups; group = "lp"; description = "CUPS printing services"; }; environment.systemPackages = [ cups.out ] ++ optional polkitEnabled cups-pk-helper; environment.etc."cups".source = "/var/lib/cups"; services.dbus.packages = [ cups.out ] ++ optional polkitEnabled cups-pk-helper; # Cups uses libusb to talk to printers, and does not use the # linux kernel driver. If the driver is not in a black list, it # gets loaded, and then cups cannot access the printers. boot.blacklistedKernelModules = [ "usblp" ]; 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; }; systemd.services.cups = { wantedBy = optionals (!cfg.startWhenNeeded) [ "multi-user.target" ]; wants = [ "network.target" ]; after = [ "network.target" ]; path = [ cups.out ]; preStart = '' mkdir -m 0700 -p /var/cache/cups mkdir -m 0700 -p /var/spool/cups mkdir -m 0755 -p ${cfg.tempDir} mkdir -m 0755 -p /var/lib/cups # Backwards compatibility if [ ! -L /etc/cups ]; then mv /etc/cups/* /var/lib/cups rmdir /etc/cups ln -s /var/lib/cups /etc/cups fi # First, clean existing symlinks if [ -n "$(ls /var/lib/cups)" ]; then for i in /var/lib/cups/*; do [ -L "$i" ] && rm "$i" done fi # Then, populate it with static files cd ${rootdir}/etc/cups for i in *; do [ ! -e "/var/lib/cups/$i" ] && ln -s "${rootdir}/etc/cups/$i" "/var/lib/cups/$i" done #update path reference [ -L /var/lib/cups/path ] && \ rm /var/lib/cups/path [ ! -e /var/lib/cups/path ] && \ ln -s ${bindir} /var/lib/cups/path ${optionalString (containsGutenprint cfg.drivers) '' if [ -d /var/lib/cups/ppd ]; then ${getGutenprint cfg.drivers}/bin/cups-genppdupdate -p /var/lib/cups/ppd fi ''} ''; serviceConfig = { PrivateTmp = true; RuntimeDirectory = [ "cups" ]; }; }; systemd.services.cups-browsed = mkIf avahiEnabled { description = "CUPS Remote Printer Discovery"; wantedBy = [ "multi-user.target" ]; wants = [ "cups.service" "avahi-daemon.service" ]; bindsTo = [ "cups.service" "avahi-daemon.service" ]; partOf = [ "cups.service" "avahi-daemon.service" ]; after = [ "cups.service" "avahi-daemon.service" ]; path = [ cups ]; serviceConfig.ExecStart = "${cups-filters}/bin/cups-browsed"; restartTriggers = [ browsedFile ]; }; services.printing.extraConf = '' DefaultAuthType Basic Order allow,deny Allow localhost Order allow,deny Allow localhost AuthType Basic Require user @SYSTEM Order allow,deny Allow localhost Require user @OWNER @SYSTEM Order deny,allow AuthType Basic Require user @SYSTEM Order deny,allow Require user @OWNER @SYSTEM Order deny,allow Order deny,allow ''; security.pam.services.cups = {}; }; }