# StartupItems

A StartupItem is a MacPorts facility to run "daemons," a Unix term for programs that run continuously in the background, rather than under the direct control of a user; for example, mail servers, network listeners, etc. Ports that use StartupItem keywords create Mac OS X scripts for launchd, which is the Apple facility introduced with Mac OS X 10.4 to replace xinetd for starting and managing daemons. To support `launchd`, a program named `daemondo` is provided by MacPorts base that serves as an adapter between Mac OS X's `launchd` and daemons (executable StartupItems) or traditional Unix startup scripts that start daemons (script StartupItems).

There are three categories of StartupItem keywords. Those that trigger StartupItem creation and logging, those that specify attributes of executable StartupItems, and those that specify attributes of script StartupItems.

The variable `startupitem_type` in `${prefix}/etc/macports/macports.conf` may be set to `none` to globally override all StartupItem keywords found in Portfiles; this prevents StartupItems from being created.

## StartupItem Attributes

The keywords in this section may be used with either executable or script StartupItems (see below).

startupitem.create

  Trigger the creation of a StartupItem.

  - Default: `no`

  - Example:

        startupitem.create      yes

startupitem.name

  Sets the name for the StartupItem. Defaults to the name of the port, so this keyword is usually unnecessary.

  - Default: `${name}`

  - Example:

        startupitem.name        dhcpd

startupitem.logfile

  Path to a logfile for logging events about the lifetime of the StartupItem. Depending on the type of StartupItem, and the manner in which it is started, standard output from the daemon may also be directed to the logfile.

  - Default: `/dev/null`

  - Example:

        startupitem.logfile     ${prefix}/var/log/mydaemon.log

startupitem.logevents

  Control whether or not to log events to the log file. If logevents is set, events with timestamps are logged to the logfile.

  - Default: `no`

  - Example:

        startupitem.logevents   yes

startupitem.netchange

  Cause the daemon to be restarted when a change in network state is detected.

  - Default: `no`

  - Example:

        startupitem.netchange   yes

## Executable StartupItems

Daemons run continuously, so monitoring the health of daemon processes and restarting them if they die is an important StartupItems' feature. Executable StartupItems are preferred over script StartupItems because `daemondo` launches the daemon directly, rather than indirectly via a script, and therefore it automatically knows how to monitor a daemon process and restart it if it dies. Daemons used with executable StartupItems may be programs or scripts (shell, perl, python, etc.), but when a script is used the script itself must be the daemon, rather than merely what launches the daemon (for the latter,script StartupItems are to be used).

For a given port, the executable StartupItem keyword may not be used with any keywords in the script StartupItem category.

startupitem.executable

  Specifies the name of the daemon to be run. It may have multiple arguments, but they must be appropriate for a call to exec; arbitrary shell code may not be used.

  Some daemons "daemonize" by detaching themselves from the controlling tty before sending themselves to the background, thus making themselves a child of the original process. A daemon to be started with `startupitem.executable` must not be allowed to do this (daemondo will think the process has died and start another instance); this can usually be turned off with a switch so the daemon does not detach itself (runs as a foreground process).

  - Default: none

  - Example:

        startupitem.executable  ${prefix}/sbin/vm-pop3d -d 10 -t 600

  Do not wrap values in quotes if passing arguments to the daemon; executable StartupItem elements must be tagged individually so the spaces between arguments serve as delimiters for string tags. For example, this startupitem key/value pair:

      startupitem.executable    ${prefix}/sbin/vm-pop3d -d 10 -t 600

  generates a .plist file with these tags:

      <key>ProgramArguments</key>
      <array>
          <string>/opt/local/bin/daemondo</string>
          <string>--label=vm-pop3d</string>
          <string>--start-cmd</string>
          <string>/opt/local/sbin/vm-pop3d</string>
          <string>-d</string>
          <string>10</string>
          <string>-t</string>
          <string>600</string>
          <string>;</string>
      </array>

## Script StartupItems

StartupItems of type script use `daemondo` to launch a daemon indirectly via a startup script. A typical snippet of a startup script that may be used with a script StartupItem is shown below. Notice that the script is not a daemon; rather the script indirectly launches the vm-pop3d daemon.

    #!/bin/sh

    case "$1" in
        start)
            echo -n "Starting vm-pop3d: "
            /opt/local/sbin/vm-pop3d -d 10 -t 600

    [... trimmed ...]

But if a script itself is a daemon, use the executable StartupItem type since that way it will be launched directly and its health tracked automatically. When using script StartupItems, the `startupitem.pidfile` keyword must be used if you want `daemondo` to monitor a daemon process and restart it if it dies.

For a given port, StartupItem keywords in category script may not be used with an executable StartupItem keyword.

startupitem.start
startupitem.stop
startupitem.restart

  Specify a shell script to start, stop, and restart the daemon. In the absence of `startupitem.restart`, the daemon will be restarted by taking the stop action, followed by the start action.

  - Default: none

  - Examples:

        startupitem.start       "${prefix}/share/mysql/mysql.server start"
        startupitem.stop        "${prefix}/share/mysql/mysql.server stop"
        startupitem.restart     "${prefix}/share/mysql/mysql.server restart"

  Wrap the stop, start, and restart values in quotes so they will be placed in the wrapper tagged as a single element.

startupitem.init

  Shell code that will be executed prior to any of the options `startupitem.start`, `startupitem.stop` and `startupitem.restart`.

  - Default: none

  - Example:

        startupitem.init        BIN=${prefix}/sbin/bacula-fd

startupitem.pidfile

  This keyword must be defined properly for `daemondo` to be able to monitor daemons launched via script StartupItems and restart them if they die. It specifies two things: a process id (PID) file handling method, and a pidfile name and path.

  - Default: `none ${prefix}/var/run/${name}.pid`

    Default: [none] | [`${prefix}/var/run/${name}.pid`]

  - Values [none auto manual clean] [/path/to/pidfile]

  - Example:

        startupitem.pidfile     auto ${prefix}/var/run/${name}.pidfile

  PID file handling options:

  - `none` - daemondo will not create or track a PID file, so it won't know when a daemon dies.

  - `auto` - The started process is expected to create a PID file that contains the PID of the running daemon; daemondo then reads the PID from the file and tracks the process. The started process must delete the PID file if this is necessary.

  - `clean` - The started process is expected to create a PID file that contains the PID of the running daemon; daemondo then reads the PID from the file and tracks the process, and deletes the PID file if it detects the daemon has died.

  - `manual` - This option should only be used if an executable StartupItem could be used (daemondo launches a daemon directly) and a port author wants a PID file written for some special use. A PID file is not needed to detect process death for daemons launched directly by daemondo. As with executable StartupItems, daemondo remembers the PID of the launched process and tracks it automatically.

## Loading / Unloading StartupItems into launchd

A port with a StartupItem places a link to a .plist file for the port's daemon within `/Library/LaunchDaemons/`. A .plist file is an XML file; MacPorts installs .plist files tagged as disabled for the sake of security. You may enable a startup script (tag the.plist file as enabled) and load it into `launchd` with a single command as shown.

    %% sudo launchctl load -w /Library/LaunchDaemons/org.macports.mysql5.plist

You may stop a running startup script, disable it (tag the.plist file as disabled), and unload it from `launchd` with a single command as shown.

    %% sudo launchctl unload -w /Library/LaunchDaemons/org.macports.mysql5.plist

## StartupItem Internals

During port installation a MacPorts StartupItem creates a .plist file in `${prefix}/etc/LaunchDaemons/`, and places a symbolic link to the .plist file within `/Library/LaunchDaemons/`.

For example, the StartupItem for the mysql5 port is `org.macports.mysql5.plist`, and it is linked as shown.

    %% ls -l /Library/LaunchDaemons

    org.macports.mysql5.plist ->
         /opt/local/etc/LaunchDaemons/org.macports.mysql5/org.macports.mysql5.plist

For script StartupItems, in addition to a .plist file, a wrapper is also created.

    %% ls -l /opt/local/etc/LaunchDaemons/org.macports.mysql5/

    -rwxr-xr-x   2 root  wheel  475 Aug  2 14:16 mysql5.wrapper
    -rw-r--r--   2 root  wheel  975 Aug  2 14:16 org.macports.mysql5.plist

The wrapper manipulates the script as specified in the startupitem.start and startupitem.stop keywords. An example wrapper script snippet is shown below.

    #!/bin/sh

    # MacPorts generated daemondo support script

    # Start
    Start()
    {
        /opt/local/share/mysql5/mysql/mysql.server start
    }

    # Stop
    Stop()
    {
        /opt/local/share/mysql5/mysql/mysql.server stop
    }

    [... trimmed ...]