relaunchd

Overview

relaunchd is a service management daemon that is similar to the launchd(8) facility found in the Darwin operating environment [1].

It was written from scratch based on the published API, and all code is available under the ISC license. See the LICENSE file for more information.

It is currently under heavy development, and should not be used for anything important. Be especially mindful that there is NO WARRANTY provided with this software.

Status

See the release notes for details about the current release.

relaunchd aims to support the following platforms:

FreeBSD 9, 10, and 11-CURRENT
OpenBSD 5.8
NetBSD 7.0
Linux (various flavors)

The core functionality is working:

loading and unloading jobs with launchctl
launching jobs
socket-activated jobs via the Sockets key
periodic jobs that use the StartInterval key

There are some new features not found in the original launchd:

JSON is used instead of XML
a wrapper library that allows programs to use socket activation without modifying the source code.

Some things are not implemented yet:

cron emulation (see issue #17)
file and directory watches (see issue #25)
resource limits (see issue #27)
LaunchOnlyOnce (see issue #28)
inetdCompatibility (see issue #29)

Some things will probably never be implemented:

oddities - LimitLoadToHosts, LimitLoadFromHosts
kernel and launchd debugging - Debug, WaitForDebugger
Mach IPC
the StartOnMount key - may require kernel support for filesystem mount notifications
the original XML plist format; use JSON instead.
hacks and workarounds - HopefullyExitsFirst, HopefullyExitsLast
Darwin-specific things - EnableTransactions
legacy keys - Disabled, OnDemand

Building from source

The basic commands to build and install the software are:

	mkdir cmake-build-debug
	cd cmake-build-debug
	cmake ..
	make

You can check the current build status by visiting the Travis CI dashboard.

Socket activation

relaunchd uses a different mechanism for socket activation than the one that Darwin uses.

TODO -- document this

Installation

Currently, relaunchd has only been tested on FreeBSD, but should be portable to other BSD operating systems.

To install relaunchd, run the following commands:

make
sudo make install

This will install the following executable commands:

launchd
launchctl

It will also install the following manpages:

launchctl(1)
launchd(8)
launchd.plist(5)

Usage

To start launchd, run the following command as root:

service launchd start

If you want to run jobs in your graphical user session, add the following lines to your session startup file:

launchctl load ~/.launchd/agents /usr/local/etc/launchd/agents /usr/local/share/launchd/agents

Differences with Darwin launchd

There are some specific design choices that make relaunchd different from the or iginal launchd found in Darwin.

The original launchd uses friendly MacOS-style names for the directories where its configuration files are stored. For example, one of the directories is named /System/Library/LaunchDaemons. Relaunchd uses more traditional lowercase names, and stores it's files in:

$HOME/.launchd/agents
/usr/local/etc/launchd/agents
/usr/local/etc/launchd/daemons
    /usr/local/share/launchd/daemons
    /usr/local/share/launchd/agents

On FreeBSD, there is no compelling reason to have launchd run as pid #1, so relaunchd is designed to be started by the traditional init(8) command. Relaunchd currently coexists with the /etc/rc mechanism, until such time as all of the /etc/rc.d scripts can be converted to launchd jobs.

Instead of using the XML plist format, job manifests are specified using JSON.

In the Darwin implementation, there is a single launchd(8) process that is accessible to all user accounts. In relaunchd, there is a "system launchd" process that runs as root and is not accessible by unprivileged users. Each unprivileged user may run their own launchd process under their own UID.

In the Darwin implementation, the StartCalendarInterval key can be a hash or an array of hashes. In relaunchd, only a hash is acceptable.

In the Darwin implementation, the Umask key is a decimal integer. In relaunchd, octal notation is used, but converted to a string.

Static Analysis

Coverity scan reports for relaunchd are available at: https://scan.coverity.com/projects/mheily-relaunchd?tab=overview

When new releases are created, they will be submitted to Coverity to re-run the static analyzer.

Contact Information

For questions, comments, or other feedback about relaunchd, please open an issue on the GitHub page.

Links

Here are some links to useful information about launchd:

References

[1] https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man8/launchd.8.html

RJVB/relaunchd-mh