There is a search function in NodeBB. But I used it and could not find my topics. So I asked for improvement and somebody else asked about a lot of specific search features (e.g. order by most replys etc.). As I'm used to ElasticSearch I catched up the idea to make a plugin. But I'm not very familar with the plug-in API. Some Hooks I wanted (e.g. overwrite the inbuid search function) might not be available. Another issue might be to update edited posts (I get no event for it ..).
On my prototype I get very good search results (as expected) and can use complete Lucene query syntax.
I think with little work of the NodeBB team and somebody helping me to point to the right (new) hooks in my plugin would create high value for scalable large NodeBB sites.
I plan to use it in my intranet and closed customer support platform (that's why I asking for a lot of security features, removal of social network buttons etc.)