Elasticsearch cluster plugin settings

I'm working on custom plugin that intercepts some queries and i need to store plugin configuration somewhere. I choose properties file and assemble it with all other plugin meta files, but such solution won't work with cluster environment. Because to change some properties user needs to update all property files on each server or reinstall plugin. So now I'm looking for storing plugin configs in index. But currently I can't find an API to do this PROGRAMMATICALLY.
I found that I can Inject NodeClient to my plugin and execute some SearchAction and process the result. Is it a good solution or maybe there are some other ways to do that?