# Web Updater

Ren'Py includes an updater that can automatically download and install updates to a Ren'Py game from a web host. The updates work on Windows and Linux, but not macOS, Android, or iOS.

The Ren'Py updater works by automatically performing the following steps:

1. Downloading an index file that controls what is updated.

2. Asking the user if he or she wants to proceed with the update.

3. Producing an archive file from the files on disk.

4. Downloading a zsync control file from the server.

5. Using the zsync tool to update the archive file to the version on the server. Zsync automatically computes the differences between the two files, and attempts to only download the portions that have changed.

6. Unpacking the archive, replacing the files on disk.

7. Deleting files that have been removed between the old and new versions.

8. Restarting the game.

The Ren'Py updater shows an updater screen during this process, prompting the user to proceed and allowing the user to cancel when appropriate.

## Server Requirements

The updater requires that you provide your own hosting. You should be able to download the update files by going to the appropriate URL directly, and your server must support HTTP range queries.

HTTPS is not supported for patching, but will download the entire file, not the patch.

(This means paying for web hosting, as "sharing" sites tend not to support the required features.)

If the patch parameter is set to False, or an https url is given, the updater will not attempt to patch the game. Instead, it will download the full archive, and unpack that update. While this is a larger download, it will work with many more web servers.

## Building an Update

Updates are built automatically when distributions are built. To build an update, set `build.include_update` to True in options.rpy. This will unlock the "Build Updates" option in the "Build Distributions" section of the launcher. Check this option, and Ren'Py will create the update files.

The update files consist of:

updates.json

  An index of available updates and their versions.

package.sums

  Contains checksums for each block in the package.

package.update.gz

  Contains the update data for the given package.

package.update.json

  Contains a list of the files in each package, which the updater uses when downloading DLC.

package.zsync

  This is a control file that's used by zsync to manage the download.

You must upload all these files to a single directory on your web server.

## Functions

To cause an update to occur, invoke either updater.update or the updater.Update action.

## Screen

To customize the look of the updater, you may override the `updater` screen. The default screen is defined in common/00updater.rpy.