dropsync-rs: A Rust repository from toolness

This is a command-line tool I, Atul Varma, wrote to help me synchronize application-specific data (usually saved game data) across multiple computers using Dropbox.

Note that this tool doesn't actually use the network itself: it simply assumes that the directory Dropbox, located off the user's home directory, is automatically synchronized with other computers. It could be a shared network drive, or it could even be manually copied to other computers via USB stick.

Disclaimer: I wrote this tool because I wanted to write something in Rust. It's likely that there are better alternatives out there!

Installation

You'll need Rust.

Clone this repository, enter it in your terminal, and run:

cargo install --path . --force

Now the dropsync executable should be on your path. You can verify this by running:

dropsync --help

Before actually using the tool, however, you'll need to configure it.

Configuration

Before using this tool, create a file called dropsync.toml in the root of your Dropbox folder. It should contain entries for each app you want to synchronize like so:

[MyFunkyGame]
path = "C:\\Users\\Atul\\AppData\\Local\\MyFunkyGame\\Saved\\SaveGames"
dropbox_path = "Games/MyFunkyGame"

[MyOtherGame]
path = "C:\\Users\\Atul\\Documents\\My Games\\MyFunkyGame"
dropbox_path = "Games/MyFunkyGame"

Each section corresponds to a specific application whose data you want to synchronize and has the following entries:

path is the absolute path to where the application expects to find and save its data.
dropbox_path is the path relative to the Dropbox folder where the data will be synchronized.
disabled is an optional boolean; if true, the application entry will be ignored.
include_only is a glob pattern, like *.sv, which makes dropsync only synchronize files that match the pattern.
play_path is the optional path to where the application's executable is. If provided, you will be able to use the dropsync play <app name> command, which may be convenient.
play_root_path is an optional absolute path to an ancestor directory of the application's executable. If supplied, play_path will be appended to it (otherwise, play_path should be absolute).

Most significantly, this path will also be used as the root directory to watch to determine whether the app has finished running. If, for instance, the play_path points to a "launcher" that launches the actual app, which is also under play_root_path, then providing this value will ensure that dropsync doesn't try to synchronize files until after the actual app has finished running.

If different computers have the applications at different locations, a separate subsection denoted by the computer's hostname can store host-specific configuration overrides, e.g.:

[MyFunkyGame]
# The default app path on all computers unless overridden.
path = "C:\\Users\\Atul\\AppData\\Local\\MyFunkyGame\\Saved\\SaveGames"
dropbox_path = "Games/MyFunkyGame"

[MyFunkyGame.MY_WEIRD_DESKTOP_COMPUTER]
# This will override the default app path on MY_WEIRD_DESKTOP_COMPUTER.
path = "F:\\MyFunkyGame\\Saved\\SaveGames"

Note that in the above example MY_WEIRD_COMPUTER is the name of the computer. (On Windows, the name of your computer can be found by typing "computer name" into the search box at the bottom-left of the task bar; on other systems, try typing hostname in the terminal.)

Note that all directories do need to exist before running the program, so you'll want to create them manually if they don't already exist.

Usage

Once you've created your dropsync.toml, you can synchronize your application data by running:

dropsync

The synchronization process is imperfect but should work in most cases, with the following assumptions:

You remember to manually run this tool before and after you're done using the relevant applications. Alternatively, you can also use dropsync play <app name> to first synchronize, then play (assuming play_path has been set for the relevant app), and then re-synchronize the app.
No one else is using the applications at the same time as you on your other computers.

The tool works by comparing the contents of the application's data folder and its Dropbox analog. If one folder is non-empty, has no files that are older than their equivalent in the other folder, and has at least one file that is newer than its equivalent in the other folder, then the folder is considered to be the newer version of the data, and its entire contents are copied to the other folder. Files in the older folder that don't exist in the newer folder are deleted.

If the contents of both folders aren't exactly equal, and if neither is judged to be newer than the other, then the user is prompted to manually resolve the conflict.

Version history

1.0.0

Initial release.

1.1.0 - 2020-10-10