Unisonbox

Author: Tim Creech

Disclaimer

This project is provided as-is, without any express or implied warranty. Although I have used it without incident for a year or so, I cannot be held responsible for any related losses or damages. I would advise the use of automated backups just in case something goes terribly wrong!

Explanation

This is a small collection of simple scripts I use on my personal machines to effect Dropbox-like synchronization on my machines. Each machine stores all synchronized files locally, and these scripts take care of regularly keeping things up to date. A central server is required, around which your nodes will form a simple star toplogy.

I created this for personal use, and thought that it might be useful as a starting point for others who want to set up something similar. You will probably have to change each file in this repository a bit in order to get things up and running.

All of the heavy lifting is done by the excellent Unison File Synchronizer from UPenn. (www.cis.upenn.edu/~bcpierce/unison/)

Installation

Quick guide to getting a "box" set up.

Client Requirements

• Unison (the same version on all participating nodes!)
• Something like crontab or launchd to regularly run the sync command
• The choose-tcp-host command (included in this repo)

Server Requirements

• Properly populated ~/.ssh/authorized_keys
• Unison

General Idea

Create a script based on boxsync for your directory to sync. For example, I like to sync ~/school, so I create a ~/bin/schoolsync script based on boxsync. Edit this script to set up the configuration variables, which are mostly self-explanatory. Make sure that you give it the correct location of choose-tcp-host, and a good list of hostnames to check. For example, on your laptop client, you might set HOSTLIST="server.local server.selfip.com" to have the laptop access your server on the local network if available, and otherwise go over the internet. Of course, it's fine to just put a single host in this list. Based on the name you gave the script, a log will be created in /tmp/. For schoolsync, this log is /tmp/schoolsync.log. This script just needs to run on all the clients, not the sever.

You can do a test sync by manually invoking your sync script. After things are working and you are comfortable with what is happening, schedule the script to be run every few minutes automatically. Cron and launchd examples are included in this repository.