Dynamic Plugin Loading: Even though Solr came with a ton of features out of the box, loading and managing custom plugins in Apache Solr has not been very elegant. Recently, starting from 8.2, there has been a lot of work in this direction, and Solr now has easy to use repository based dynamic plugin loading and management capabilities.
Safe-mode Solr: This is a solution to have Solr deployed only with a minimal set of whitelisted features that are useful for most users, and are known to be safe, even when exposed to a public facing interface (with properly configured authorization and authentication). Some of the non-whitelisted features in the safe mode are contrib modules, cross-collection joins, Tika extractions, DIH, HDFS support, etc.
Future plans: The eventual goal of both these initiatives is to make core Solr more lean by having essential, core features of Solr be available out of the box, and non-essential features be available to be used using plugins.
Ishan Chattopadhyaya, Committer & PMC Member, FullStory
Noble Paul, Committer & PMC Member, FullStory