Usecase I want to combine full text search of Discourse and Wordpress to be used in both the WP search box and the Discourse search box. I’m open to any CMS actually, but figure Wordpress is most likely.
Request I am hoping there is someone here that uses Elastic Search with Discourse combined with WordPress or some other CMS. I would love a tutorial. 
Here are a couple refs from my bro, thought-crime-ai google:
2 years old, looks like it should still work. I’ll probably try it. I will still have to integrate WP Elastic Search.
discourse maintained, elastic search image with aws plugin… what / how is this used by discourse? Maybe for larger hosted clients? Probably.
lol Elastic.co themselves use Discourse… and there is no tutorial or whatever on how to use Elastic Search for Discourse.
https://mirasvit.com/docs/module-search-elastic-ultimate/current/module-search/current/indexes/index#wordpress
Here is an Elastic Search extension / plugin for Magento2 which allows Elastic Search to index Wordpress as well. Looking at the manual (above) it appears that Magento2 just gets the database credentials for WP and indexes the wp_posts table with the Magento2 data and the extension handles the routing.
—edit to add—
Here is how to store multiple db’s in a single ES index.