Save https://yoursite/admin/site_settings.json. Use https://github.com/pfaffman/discourse-settings-uploader to upload them.
To install these settings to another site
Do this:
./discourse-settings-uploader HOSTURL API_KEY API_USER SETTINGS_FILE
For example:
./discourse-settings-uploader https://discourse.example.com d35989078a system site_settings.json
One caveat: It uploads only settings that are marked as changed. This means that if there’s some setting that’s changed on the site you’ve uploaded that you want to restore to default with the script it won’t work. The solution is to edit the JSON file so that the default value there doesn’t match the value you want to set.
Now what’s needed is a way to easily download all themes and then upload them. Uploading
a set of files shouldn’t be hard to do. Downloading themes by hand could be tedious, so some automated way to get all of them would be nice.