add launchd module

3 files changed, 709 insertions, 0 deletions

diff --git a/modules/launchd/default.nix b/modules/launchd/default.nix
new file mode 100644
index 0000000..a735c76
--- /dev/null
+++ b/modules/launchd/default.nix
@@ -0,0 +1,123 @@
+{ config, lib, pkgs, ... }:
+
+with import ./lib.nix { inherit lib; };
+with lib;
+
+let
+
+  cfg = config.launchd;
+
+  launchdConfig = import ./launchd.nix;
+
+  serviceOptions =
+    { config, name, ... }:
+    { options = {
+        plist = mkOption {
+          type = types.path;
+          internal = true;
+          description = "The generated plist.";
+        };
+
+        serviceConfig = mkOption {
+          type = types.submodule launchdConfig;
+          example =
+            { Program = "/run/current-system/sw/bin/nix-daemon";
+              KeepAlive = true;
+            };
+          default = {};
+          description = ''
+            Each attribute in this set specifies an option for a <key> in the plist.
+            https://developer.apple.com/legacy/library/documentation/Darwin/Reference/ManPages/man5/launchd.plist.5.html
+          '';
+        };
+      };
+
+      config = {
+        serviceConfig.Label = mkDefault "org.nixos.${name}";
+
+        plist = pkgs.writeText "${config.serviceConfig.Label}.plist" ''
+          <?xml version="1.0" encoding="UTF-8"?>
+          <!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+          <plist version="1.0">
+            <dict>
+              ${xmlMapAttr xmlString "Label" config.serviceConfig.Label}
+              ${xmlMapAttr xmlBool "Disabled" config.serviceConfig.Disabled}
+              ${xmlMapAttr xmlString "UserName" config.serviceConfig.UserName}
+              ${xmlMapAttr xmlString "GroupName" config.serviceConfig.GroupName}
+              ${xmlMapAttr (xmlMapAttrs xmlBool) "inetdCompatibility" config.serviceConfig.inetdCompatibility}
+              ${xmlMapAttr (xmlMap xmlString) "LimitLoadToHosts" config.serviceConfig.LimitLoadToHosts}
+              ${xmlMapAttr (xmlMap xmlString) "LimitLoadFromHosts" config.serviceConfig.LimitLoadFromHosts}
+              ${xmlMapAttr xmlString "LimitLoadToSessionType" config.serviceConfig.LimitLoadToSessionType}
+              ${xmlMapAttr xmlString "Program" config.serviceConfig.Program}
+              ${xmlMapAttr (xmlMap xmlString) "ProgramArguments" config.serviceConfig.ProgramArguments}
+              ${xmlMapAttr xmlBool "EnableGlobbing" config.serviceConfig.EnableGlobbing}
+              ${xmlMapAttr xmlBool "EnableTransactions" config.serviceConfig.EnableTransactions}
+              ${xmlMapAttr xmlBool "OnDemand" config.serviceConfig.OnDemand}
+              ${xmlMapAttr xmlBool "KeepAlive" config.serviceConfig.KeepAlive}
+              ${xmlMapAttr xmlBool "RunAtLoad" config.serviceConfig.RunAtLoad}
+              ${xmlMapAttr xmlString "RootDirectory" config.serviceConfig.RootDirectory}
+              ${xmlMapAttr xmlString "WorkingDirectory" config.serviceConfig.WorkingDirectory}
+              ${xmlMapAttr (xmlMapAttrs xmlString) "EnvironmentVariables" config.serviceConfig.EnvironmentVariables}
+              ${xmlMapAttr xmlInt "Umask" config.serviceConfig.Umask}
+              ${xmlMapAttr xmlInt "TimeOut" config.serviceConfig.TimeOut}
+              ${xmlMapAttr xmlInt "ExitTimeOut" config.serviceConfig.ExitTimeOut}
+              ${xmlMapAttr xmlInt "ThrottleInterval" config.serviceConfig.ThrottleInterval}
+              ${xmlMapAttr xmlBool "InitGroups" config.serviceConfig.InitGroups}
+              ${xmlMapAttr (xmlMap xmlString) "WatchPaths" config.serviceConfig.WatchPaths}
+              ${xmlMapAttr (xmlMap xmlString) "QueueDirectories" config.serviceConfig.QueueDirectories}
+              ${xmlMapAttr xmlBool "StartOnMount" config.serviceConfig.StartOnMount}
+              ${xmlMapAttr xmlInt "StartInterval" config.serviceConfig.StartInterval}
+              ${xmlMapAttr (xmlMapAttrs xmlInt) "StartCalendarInterval" config.serviceConfig.StartCalendarInterval}
+              ${xmlMapAttr xmlString "StandardInPath" config.serviceConfig.StandardInPath}
+              ${xmlMapAttr xmlString "StandardOutPath" config.serviceConfig.StandardOutPath}
+              ${xmlMapAttr xmlString "StandardErrorPath" config.serviceConfig.StandardErrorPath}
+              ${xmlMapAttr xmlBool "Debug" config.serviceConfig.Debug}
+              ${xmlMapAttr xmlBool "WaitForDebugger" config.serviceConfig.WaitForDebugger}
+              ${xmlMapAttr (xmlMapAttrs xmlInt) "SoftResourceLimits" config.serviceConfig.SoftResourceLimits}
+              ${xmlMapAttr (xmlMapAttrs xmlInt) "HardResourceLimits" config.serviceConfig.HardResourceLimits}
+              ${xmlMapAttr xmlInt "Nice" config.serviceConfig.Nice}
+              ${xmlMapAttr xmlString "ProcessType" config.serviceConfig.ProcessType}
+              ${xmlMapAttr xmlBool "AbandonProcessGroup" config.serviceConfig.AbandonProcessGroup}
+              ${xmlMapAttr xmlBool "LowPriorityIO" config.serviceConfig.LowPriorityIO}
+              ${xmlMapAttr xmlBool "LaunchOnlyOnce" config.serviceConfig.LaunchOnlyOnce}
+              ${xmlMapAttr (xmlMapAttrs xmlBool) "MachServices" config.serviceConfig.MachServices}
+            </dict>
+          </plist>
+        '';
+      };
+    };
+
+in {
+  options = {
+
+    launchd.agents = mkOption {
+      default = {};
+      type = types.attrsOf (types.submodule serviceOptions);
+      description = "Definition of launchd agents.";
+    };
+
+    launchd.daemons = mkOption {
+      default = {};
+      type = types.attrsOf (types.submodule serviceOptions);
+      description = "Definition of launchd daemons.";
+    };
+
+    launchd.user.agents = mkOption {
+      default = {};
+      type = types.attrsOf (types.submodule serviceOptions);
+      description = "Definition of launchd per-user agents.";
+    };
+
+  };
+
+  config = {
+
+    system.activationScripts.launchd.text = ''
+      # Set up launchd services in /Library/LaunchAgents, /Library/LaunchDaemons and ~/Library/LaunchAgents
+      echo "setting up launchd services..."
+      echo "TODO"
+      exit 2
+    '';
+
+  };
+}
diff --git a/modules/launchd/launchd.nix b/modules/launchd/launchd.nix
new file mode 100644
index 0000000..b5a42cc
--- /dev/null
+++ b/modules/launchd/launchd.nix
@@ -0,0 +1,558 @@
+{ config, lib, ... }:
+
+with lib;
+
+{
+  options = {
+    Label = mkOption {
+      type = types.str;
+      description = ''
+        This required key uniquely identifies the job to launchd.
+      '';
+    };
+
+    Disabled = mkOption {
+      type = types.nullOr types.bool;
+      default = null;
+      description = ''
+        This optional key is used as a hint to launchctl(1) that it should not submit this job to launchd when
+        loading a job or jobs. The value of this key does NOT reflect the current state of the job on the run-ning running
+        ning system. If you wish to know whether a job is loaded in launchd, reading this key from a configura-tion configuration
+        tion file yourself is not a sufficient test. You should query launchd for the presence of the job using
+        the launchctl(1) list subcommand or use the ServiceManagement framework's SMJobCopyDictionary() method.
+
+        Note that as of Mac OS X v10.6, this key's value in a configuration file conveys a default value, which
+        is changed with the [-w] option of the launchctl(1) load and unload subcommands. These subcommands no
+        longer modify the configuration file, so the value displayed in the configuration file is not necessar-ily necessarily
+        ily the value that launchctl(1) will apply. See launchctl(1) for more information.
+
+        Please also be mindful that you should only use this key if the provided on-demand and KeepAlive crite-ria criteria
+        ria are insufficient to describe the conditions under which your job needs to run. The cost to have a
+        job loaded in launchd is negligible, so there is no harm in loading a job which only runs once or very
+        rarely.
+      '';
+    };
+
+    UserName = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      description = ''
+        This optional key specifies the user to run the job as. This key is only applicable when launchd is
+        running as root.
+      '';
+    };
+
+    GroupName = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      description = ''
+        This optional key specifies the group to run the job as. This key is only applicable when launchd is
+        running as root. If UserName is set and GroupName is not, the the group will be set to the default
+        group of the user.
+      '';
+    };
+
+    # TODO
+    inetdCompatibility = mkOption {
+      type = types.nullOr (types.attrsOf types.bool);
+      default = null;
+      example = { Wait = true; };
+      description = ''
+        The presence of this key specifies that the daemon expects to be run as if it were launched from inetd.
+
+        This flag corresponds to the "wait" or "nowait" option of inetd. If true, then the listening
+        socket is passed via the standard in/out/error file descriptors. If false, then accept(2) is
+        called on behalf of the job, and the result is passed via the standard in/out/error descriptors.
+      '';
+    };
+
+    LimitLoadToHosts = mkOption {
+      type = types.nullOr (types.listOf types.str);
+      default = null;
+      description = ''
+        This configuration file only applies to the hosts listed with this key. Note: One should set kern.host-name kern.hostname
+        name in sysctl.conf(5) for this feature to work reliably.
+      '';
+    };
+
+    LimitLoadFromHosts = mkOption {
+      type = types.nullOr (types.listOf types.str);
+      default = null;
+      description = ''
+        This configuration file only applies to hosts NOT listed with this key. Note: One should set kern.host-name kern.hostname
+        name in sysctl.conf(5) for this feature to work reliably.
+      '';
+    };
+
+    LimitLoadToSessionType = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      description = ''
+        This configuration file only applies to sessions of the type specified. This key is used in concert
+        with the -S flag to launchctl.
+      '';
+    };
+
+    Program = mkOption {
+      type = types.nullOr types.path;
+      default = null;
+      description = ''
+        This key maps to the first argument of execvp(3).  If this key is missing, then the first element of
+        the array of strings provided to the ProgramArguments will be used instead.  This key is required in
+        the absence of the ProgramArguments key.
+      '';
+    };
+
+    ProgramArguments = mkOption {
+      type = types.nullOr (types.listOf types.str);
+      default = null;
+      description = ''
+        This key maps to the second argument of execvp(3).  This key is required in the absence of the Program
+        key. Please note: many people are confused by this key. Please read execvp(3) very carefully!
+      '';
+    };
+
+    EnableGlobbing = mkOption {
+      type = types.nullOr types.bool;
+      default = null;
+      description = ''
+        This flag causes launchd to use the glob(3) mechanism to update the program arguments before invoca-tion. invocation.
+        tion.
+      '';
+    };
+
+    EnableTransactions = mkOption {
+      type = types.nullOr types.bool;
+      default = null;
+      description = ''
+        This flag instructs launchd that the job promises to use vproc_transaction_begin(3) and
+        vproc_transaction_end(3) to track outstanding transactions that need to be reconciled before the
+        process can safely terminate. If no outstanding transactions are in progress, then launchd is free to
+        send the SIGKILL signal.
+      '';
+    };
+
+    OnDemand = mkOption {
+      type = types.nullOr types.bool;
+      default = null;
+      description = ''
+        This key was used in Mac OS X 10.4 to control whether a job was kept alive or not. The default was
+        true.  This key has been deprecated and replaced in Mac OS X 10.5 and later with the more powerful
+        KeepAlive option.
+      '';
+    };
+
+    KeepAlive = mkOption {
+      type = types.nullOr types.bool;
+      default = null;
+      description = ''
+        This optional key is used to control whether your job is to be kept continuously running or to let
+        demand and conditions control the invocation. The default is false and therefore only demand will start
+        the job. The value may be set to true to unconditionally keep the job alive. Alternatively, a dictio-nary dictionary
+        nary of conditions may be specified to selectively control whether launchd keeps a job alive or not. If
+        multiple keys are provided, launchd ORs them, thus providing maximum flexibility to the job to refine
+        the logic and stall if necessary. If launchd finds no reason to restart the job, it falls back on
+        demand based invocation.  Jobs that exit quickly and frequently when configured to be kept alive will
+        be throttled to converve system resources.
+      '';
+    };
+
+    RunAtLoad = mkOption {
+      type = types.nullOr types.bool;
+      default = null;
+      description = ''
+        This optional key is used to control whether your job is launched once at the time the job is loaded.
+        The default is false.
+      '';
+    };
+
+    RootDirectory = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      description = ''
+        This optional key is used to specify a directory to chroot(2) to before running the job.
+      '';
+    };
+
+    WorkingDirectory = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      description = ''
+        This optional key is used to specify a directory to chdir(2) to before running the job.
+      '';
+    };
+
+    EnvironmentVariables = mkOption {
+      type = types.nullOr (types.attrsOf types.str);
+      default = null;
+      description = ''
+        This optional key is used to specify additional environmental variables to be set before running the
+        job.
+      '';
+    };
+
+    Umask = mkOption {
+      type = types.nullOr types.int;
+      default = null;
+      description = ''
+        This optional key specifies what value should be passed to umask(2) before running the job. Known bug:
+        Property lists don't support octal, so please convert the value to decimal.
+      '';
+    };
+
+    TimeOut = mkOption {
+      type = types.nullOr types.int;
+      default = null;
+      description = ''
+        The recommended idle time out (in seconds) to pass to the job. If no value is specified, a default time
+        out will be supplied by launchd for use by the job at check in time.
+      '';
+    };
+
+    ExitTimeOut = mkOption {
+      type = types.nullOr types.int;
+      default = null;
+      description = ''
+        The amount of time launchd waits before sending a SIGKILL signal. The default value is 20 seconds. The
+        value zero is interpreted as infinity.
+      '';
+    };
+
+    ThrottleInterval = mkOption {
+      type = types.nullOr types.int;
+      default = null;
+      description = ''
+        This key lets one override the default throttling policy imposed on jobs by launchd.  The value is in
+        seconds, and by default, jobs will not be spawned more than once every 10 seconds.  The principle
+        behind this is that jobs should linger around just in case they are needed again in the near future.
+        This not only reduces the latency of responses, but it encourages developers to amortize the cost of
+        program invocation.
+      '';
+    };
+
+    InitGroups = mkOption {
+      type = types.nullOr types.bool;
+      default = null;
+      description = ''
+        This optional key specifies whether initgroups(3) should be called before running the job.  The default
+        is true in 10.5 and false in 10.4. This key will be ignored if the UserName key is not set.
+      '';
+    };
+
+    WatchPaths = mkOption {
+      type = types.nullOr (types.listOf types.path);
+      default = null;
+      description = ''
+        This optional key causes the job to be started if any one of the listed paths are modified.
+      '';
+    };
+
+    QueueDirectories = mkOption {
+      type = types.nullOr (types.listOf types.str);
+      default = null;
+      description = ''
+        Much like the WatchPaths option, this key will watch the paths for modifications. The difference being
+        that the job will only be started if the path is a directory and the directory is not empty.
+      '';
+    };
+
+    StartOnMount = mkOption {
+      type = types.nullOr types.bool;
+      default = null;
+      description = ''
+        This optional key causes the job to be started every time a filesystem is mounted.
+      '';
+    };
+
+    StartInterval = mkOption {
+      type = types.nullOr types.int;
+      default = null;
+      description = ''
+        This optional key causes the job to be started every N seconds.  If the system is asleep, the job will
+        be started the next time the computer wakes up.  If multiple intervals transpire before the computer is
+        woken, those events will be coalesced into one event upon wake from sleep.
+      '';
+    };
+
+    # TODO
+    StartCalendarInterval = mkOption {
+      type = types.nullOr (types.attrsOf types.int);
+      default = null;
+      example = { Hour = 2; Minute = 30; };
+      description = ''
+        This optional key causes the job to be started every calendar interval as specified. Missing arguments
+        are considered to be wildcard. The semantics are much like crontab(5).  Unlike cron which skips job
+        invocations when the computer is asleep, launchd will start the job the next time the computer wakes
+        up.  If multiple intervals transpire before the computer is woken, those events will be coalesced into
+        one event upon wake from sleep.
+
+           Minute <integer>
+           The minute on which this job will be run.
+
+           Hour <integer>
+           The hour on which this job will be run.
+
+           Day <integer>
+           The day on which this job will be run.
+
+           Weekday <integer>
+           The weekday on which this job will be run (0 and 7 are Sunday).
+
+           Month <integer>
+           The month on which this job will be run.
+      '';
+    };
+
+    StandardInPath = mkOption {
+      type = types.nullOr types.path;
+      default = null;
+      description = ''
+        This optional key specifies what file should be used for data being supplied to stdin when using
+        stdio(3).
+      '';
+    };
+
+    StandardOutPath = mkOption {
+      type = types.nullOr types.path;
+      default = null;
+      description = ''
+        This optional key specifies what file should be used for data being sent to stdout when using stdio(3).
+      '';
+    };
+
+    StandardErrorPath = mkOption {
+      type = types.nullOr types.path;
+      default = null;
+      description = ''
+        This optional key specifies what file should be used for data being sent to stderr when using stdio(3).
+      '';
+    };
+
+    Debug = mkOption {
+      type = types.nullOr types.bool;
+      default = null;
+      description = ''
+        This optional key specifies that launchd should adjust its log mask temporarily to LOG_DEBUG while
+        dealing with this job.
+      '';
+    };
+
+    WaitForDebugger = mkOption {
+      type = types.nullOr types.bool;
+      default = null;
+      description = ''
+        This optional key specifies that launchd should instruct the kernel to have the job wait for a debugger
+        to attach before any code in the job is executed.
+      '';
+    };
+
+    # TODO
+    SoftResourceLimits = mkOption {
+      type = types.nullOr (types.attrsOf types.int);
+      default = null;
+    };
+
+    # TODO
+    HardResourceLimits = mkOption {
+      type = types.nullOr (types.attrsOf types.int);
+      default = null;
+      example = { NumberOfFiles = 4096; };
+      description = ''
+        Resource limits to be imposed on the job. These adjust variables set with setrlimit(2).  The following
+        keys apply:
+
+           Core <integer>
+           The largest size (in bytes) core file that may be created.
+
+           CPU <integer>
+           The maximum amount of cpu time (in seconds) to be used by each process.
+
+           Data <integer>
+           The maximum size (in bytes) of the data segment for a process; this defines how far a program may
+           extend its break with the sbrk(2) system call.
+
+           FileSize <integer>
+           The largest size (in bytes) file that may be created.
+
+           MemoryLock <integer>
+           The maximum size (in bytes) which a process may lock into memory using the mlock(2) function.
+
+           NumberOfFiles <integer>
+           The maximum number of open files for this process.  Setting this value in a system wide daemon
+           will set the sysctl(3) kern.maxfiles (SoftResourceLimits) or kern.maxfilesperproc (HardResource-Limits) (HardResourceLimits)
+           Limits) value in addition to the setrlimit(2) values.
+
+           NumberOfProcesses <integer>
+           The maximum number of simultaneous processes for this user id.  Setting this value in a system
+           wide daemon will set the sysctl(3) kern.maxproc (SoftResourceLimits) or kern.maxprocperuid
+           (HardResourceLimits) value in addition to the setrlimit(2) values.
+
+           ResidentSetSize <integer>
+           The maximum size (in bytes) to which a process's resident set size may grow.  This imposes a
+           limit on the amount of physical memory to be given to a process; if memory is tight, the system
+           will prefer to take memory from processes that are exceeding their declared resident set size.
+
+           Stack <integer>
+           The maximum size (in bytes) of the stack segment for a process; this defines how far a program's
+           stack segment may be extended.  Stack extension is performed automatically by the system.
+      '';
+    };
+
+    Nice = mkOption {
+      type = types.nullOr types.int;
+      default = null;
+      description = ''
+        This optional key specifies what nice(3) value should be applied to the daemon.
+      '';
+    };
+
+    # TODO
+    ProcessType = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      example = "Background";
+      description = ''
+        This optional key describes, at a high level, the intended purpose of the job.  The system will apply
+        resource limits based on what kind of job it is. If left unspecified, the system will apply light
+        resource limits to the job, throttling its CPU usage and I/O bandwidth. The following are valid values:
+
+           Background
+           Background jobs are generally processes that do work that was not directly requested by the user.
+           The resource limits applied to Background jobs are intended to prevent them from disrupting the
+           user experience.
+
+           Standard
+           Standard jobs are equivalent to no ProcessType being set.
+
+           Adaptive
+           Adaptive jobs move between the Background and Interactive classifications based on activity over
+           XPC connections. See xpc_transaction_begin(3) for details.
+
+           Interactive
+           Interactive jobs run with the same resource limitations as apps, that is to say, none. Interac-tive Interactive
+           tive jobs are critical to maintaining a responsive user experience, and this key should only be
+           used if an app's ability to be responsive depends on it, and cannot be made Adaptive.
+      '';
+    };
+
+    AbandonProcessGroup = mkOption {
+      type = types.nullOr types.bool;
+      default = null;
+      description = ''
+        When a job dies, launchd kills any remaining processes with the same process group ID as the job.  Set-ting Setting
+        ting this key to true disables that behavior.
+      '';
+    };
+
+    LowPriorityIO = mkOption {
+      type = types.nullOr types.bool;
+      default = null;
+      description = ''
+        This optional key specifies whether the kernel should consider this daemon to be low priority when
+        doing file system I/O.
+      '';
+    };
+
+    LaunchOnlyOnce = mkOption {
+      type = types.nullOr types.bool;
+      default = null;
+      description = ''
+        This optional key specifies whether the job can only be run once and only once.  In other words, if the
+        job cannot be safely respawned without a full machine reboot, then set this key to be true.
+      '';
+    };
+
+    # TODO
+    MachServices = mkOption {
+      type = types.nullOr (types.attrsOf types.bool);
+      default = null;
+      example = { ResetAtClose = true; };
+      description = ''
+        This optional key is used to specify Mach services to be registered with the Mach bootstrap sub-system.
+        Each key in this dictionary should be the name of service to be advertised. The value of the key must
+        be a boolean and set to true.  Alternatively, a dictionary can be used instead of a simple true value.
+
+           ResetAtClose <boolean>
+           If this boolean is false, the port is recycled, thus leaving clients to remain oblivious to the
+           demand nature of job. If the value is set to true, clients receive port death notifications when
+           the job lets go of the receive right. The port will be recreated atomically with respect to boot-strap_look_up() bootstrap_look_up()
+           strap_look_up() calls, so that clients can trust that after receiving a port death notification,
+           the new port will have already been recreated. Setting the value to true should be done with
+           care. Not all clients may be able to handle this behavior. The default value is false.
+
+           HideUntilCheckIn <boolean>
+           Reserve the name in the namespace, but cause bootstrap_look_up() to fail until the job has
+           checked in with launchd.
+
+        Finally, for the job itself, the values will be replaced with Mach ports at the time of check-in with
+        launchd.
+      '';
+    };
+
+    # TODO
+    Sockets = mkOption {
+      type = types.nullOr types.attrs;
+      default = null;
+      description = ''
+        This optional key is used to specify launch on demand sockets that can be used to let launchd know when
+        to run the job. The job must check-in to get a copy of the file descriptors using APIs outlined in
+        launch(3).  The keys of the top level Sockets dictionary can be anything. They are meant for the appli-cation application
+        cation developer to use to differentiate which descriptors correspond to which application level proto-cols protocols
+        cols (e.g. http vs. ftp vs. DNS...).  At check-in time, the value of each Sockets dictionary key will
+        be an array of descriptors. Daemon/Agent writers should consider all descriptors of a given key to be
+        to be effectively equivalent, even though each file descriptor likely represents a different networking
+        protocol which conforms to the criteria specified in the job configuration file.
+
+        The parameters below are used as inputs to call getaddrinfo(3).
+
+           SockType <string>
+           This optional key tells launchctl what type of socket to create. The default is "stream" and
+           other valid values for this key are "dgram" and "seqpacket" respectively.
+
+           SockPassive <boolean>
+           This optional key specifies whether listen(2) or connect(2) should be called on the created file
+           descriptor. The default is true ("to listen").
+
+           SockNodeName <string>
+           This optional key specifies the node to connect(2) or bind(2) to.
+
+           SockServiceName <string>
+           This optional key specifies the service on the node to connect(2) or bind(2) to.
+
+           SockFamily <string>
+           This optional key can be used to specifically request that "IPv4" or "IPv6" socket(s) be created.
+
+           SockProtocol <string>
+           This optional key specifies the protocol to be passed to socket(2).  The only value understood by
+           this key at the moment is "TCP".
+
+           SockPathName <string>
+           This optional key implies SockFamily is set to "Unix". It specifies the path to connect(2) or
+           bind(2) to.
+
+           SecureSocketWithKey <string>
+           This optional key is a variant of SockPathName. Instead of binding to a known path, a securely
+           generated socket is created and the path is assigned to the environment variable that is inher-ited inherited
+           ited by all jobs spawned by launchd.
+
+           SockPathMode <integer>
+           This optional key specifies the mode of the socket. Known bug: Property lists don't support
+           octal, so please convert the value to decimal.
+
+           Bonjour <boolean or string or array of strings>
+           This optional key can be used to request that the service be registered with the
+           mDNSResponder(8).  If the value is boolean, the service name is inferred from the SockService-Name. SockServiceName.
+           Name.
+
+           MulticastGroup <string>
+           This optional key can be used to request that the datagram socket join a multicast group.  If the
+           value is a hostname, then getaddrinfo(3) will be used to join the correct multicast address for a
+           given socket family.  If an explicit IPv4 or IPv6 address is given, it is required that the Sock-Family SockFamily
+           Family family also be set, otherwise the results are undefined.
+      '';
+    };
+  };
+
+  config = {
+  };
+}
diff --git a/modules/launchd/lib.nix b/modules/launchd/lib.nix
new file mode 100644
index 0000000..483a0d1
--- /dev/null
+++ b/modules/launchd/lib.nix
@@ -0,0 +1,28 @@
+{ lib }:
+
+with lib;
+
+rec {
+
+  xmlMap = f: xs: ''
+    <array>
+    ${concatMapStringsSep "\n" f xs}
+    </array>
+  '';
+
+  xmlMapAttrs = f: attr: ''
+    <dict>
+    ${concatStringsSep "\n" (mapAttrsFlatten (xmlMapAttr f) attr)}
+    </dict>
+  '';
+
+  xmlMapAttr = f: n: v: optionalString (v != null) ''
+    <key>${n}</key>
+    ${f v}
+  '';
+
+  xmlBool = x: if x then "<true/>" else "<false/>";
+  xmlInt = x: "<integer>${toString x}</integer>";
+  xmlString = x: "<string>${x}</string>";
+
+}