Updated launchctl plist for running rsync server daemon

Question

I wanted to update the community on my launchctl plist for running rsync as a daemon.  This is an update to this thread:
rsyncd plist for launchd -- not starting properly on reboot.
Here is my current plist in /Library/LaunchDaemons
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Disabled</key>
    <false/>
    <key>KeepAlive</key>
    <dict/>
    <key>Label</key>
    <string>rsync</string>
    <key>ProgramArguments</key>
    <array>
        <string>/usr/local/bin/rsync</string>
        <string>--daemon</string>
        <string>--no-detach</string>
        <string>--config=/Users/jabraham/RSync/rsyncd.conf</string>
    </array>
    <key>RunAtLoad</key>
    <true/>
    <key>StandardErrorPath</key>
    <string>/Users/jabraham/RSync/stderr.txt</string>
    <key>StandardOutPath</key>
    <string>/Users/jabraham/RSync/stdout.txt</string>
</dict>
</plist>
A couple of important points:
* the --no-detach argument is important.  Launchctl is responsible for keeping daemons running, so you don't want to use rsync's own facility to spawn a new daemon in the background.   I didn't have this argument before, and it worked for me with Mavericks, but with Yosemite I needed the --no-detach
* I'm using a recent rsync from Homebrew, the much-too-old one bundled with Yosemite didn't work with my hard links properly (I can't actually remember what the actual problem was, maybe it didn't report an existing hard linking error properly, I was trying to hardlink on a file system that didn't support it.)  The Homebrew one is in /usr/local/bin.  If you don't have rsync from Homebrew or Macports the default one is version 2.6.9 and it's in /usr/bin
* I used LaunchControl from http://www.soma-zone.com/ I recommend it to setup options and to debug your typos and problems in launch daemons.

Answer 1

There are several problems with your .plist, so it's hard to know which one is causing the problem.
For one you have both a Program and a ProgramArguments key, when you should have only one or the other (you use Program if there is just one element to the command, or ProgramArguments if there are multiple.
Beyond that, though, it's not clear which execution model you're trying to use. launchd can run tasks either on demand (i.e. when some event happens that triggers the process to launch) or continuously (where launchd watches the process and automatically restarts it if it fails).
The fact you're specifying network sockets would normally indicate that you're running on demand (i.e. launchd should start rsync whenever an incoming network connection is detected). However, your ProgramArguments includes a --daemon parameter to rsync, which tells it to run continuously and listen for network connections itself. These options are incompatible (i.e. either launchd or rsync can listen to the network, but not both).
You should decide which model to employ - either let launchd listen to the network and run rsync as needed, or run rsync as a daemon and let it listen to the network.
As I said above, it isn't clear which (if either) of these is the root cause of your problem, but they need to be fixed before any more debugging can take place.