itchy

A super simple version checker for use with LÖVE games published on itch.io.

Installation

Copy itchy.lua to where you want in your source. It is recommended that you install luajit-request as it allows for itchy to use HTTPS connections.

luajit-request on Windows requires a libcurl DLL to be alongside the executable of a fused game, or in the root-level source directory for an unfused game. You can find them here. On Mac OS, this should be already installed, and most Linux distributions have it installed already. Please tell your Linux users to install libcurl if they do not have it and you are relying on its functionality.

(I don't remember which of these is which, but I have verified this DLL works for 32-bit builds, and this DLL is the 64-bit version of it.)

Usage

Start it as a thread with a configuration table. Wait for "itchy" channel to respond with a table of version information.

Require itchy, and run check_version with a configuration table. Periodically run new_version to see if data has been returned yet.

local itchy = require "lib.itchy"       -- or wherever you saved it
local game = {
  target = "guard13007/asteroid-dodge", -- target or url must be defined
  version = "1.0.0"                     -- optional, config options listed below
}
itchy:check_version(game)

-- somewhere where this will be called periodically
local data = itchy:new_version(game)  -- passing the game table is not necessary
if data then
  -- easiest usage, just print the message to the user
  love.graphics.print("Version: 1.0.0 Latest: " .. data.message)
end

You can cancel it with itchy:kill_version_checker(game), and start a new version checker with itchy:check_version({}) any time you like.

Version Information Example

Returned data example:

{
  status = 200,                -- nil or status code of an HTTP request
  body = '{"latest":"0.2.0"}', -- raw result body from the HTTP request
  version = "0.2.0",           -- number/string (if body was parsed correctly)
  latest = true,               -- nil/boolean: your version == latest version?
  message = "0.2.0, you have the latest version"   -- an error or status message
}

Errors from LuaSocket will be returned as "socket.http.request error: " .. err

The library tries to parse a response body for valid JSON of the format {"latest":"VERSION"} (itch.io's format) and will do basic version comparisons based on this value. If it is unable to extract it or compare, version and latest will be nil.

If HTTP status 200 (OK) is encountered or a version is successfully parsed from a response, the script terminates (or moves on to checking on an interval.) Otherwise, it will keep trying with an exponential back-off starting at a 1 second delay, capped at retrying every 10 minutes.

Configuration Options

At minimum a url or target must be specified.

• url (string) If you have a different URL to check for the latest version from, you can specify it here.
• target (string) The target string of your game on itch.io (username/game-slug).
• channel (string) If you do not specify the channel name to look for on itch.io, it will use osx for Mac OS / OS X, win32 for Windows, linux for Linux, android for Android, ios for iOS, and if any other OS is returned by love.system.getOS() it will use that string as-is.
• version (string/number) Version of the game running right now.
• interval (number) If specified, a check for the latest version will happen again every interval seconds.
• luajit_request (string) luajit-request is checked for in . and lib/., if you have it elsewhere, specify its location here.

The following options are available, but generally should be left for itchy to handle itself:

• proxy (string) An HTTP proxy is used if luajit-request is unavailable, unless proxy == false. By default, https://45.55.113.149:16343 is used, which is running on a DigitalOcean VPS I own. You can specify a different proxy here.
• thread_channel (string) itchy uses a channel named itchy for version checking. You can call itchy's functions with different data tables and it will use different threads & channels for each. You can also specify a channel name here.