Getting Drupal 8 to use an external index? I have two sites one is maintained by us in drupal 8 and the other is maintained by another company that does the news updates etc for our company. I'm trying to figure out the best way to get a combined search in drupal. So set up a Solr instance and setup a web crawler to crawl the other site, set up drupal 8 to use the search api and solr search. But now i'm not sure what's the best way to integrate the index created by the web crawler with drupal 8. Any ideas?
What you could do is use the Migrate module to migrate content from one site to the other. What you need to do is:


Build a custom source plugin for it so that it fetches its data from an external source (i.e. the other site) and map it to a content type in your Drupal install. 
Then set up a cron job to run the migration periodically to update the data on your end. Make sure you set the migration to "update" since by default, migrations won't happen on already-migrated content.
Create your search however you want in your site (Views, Search API, etc.) using that content type.


In D7, this was a job for the Feeds module but they don't appear to have a D8 version yet.