I previously had node based definitions for a few custom Analyzers that were used in a few index template mappings.
Now in 5.X that isn't OK, so I moved all those to my templates in the settings and new ones get created just fine.
BUT the old ones -- those have an annoying chicken and egg scenario. They can't reopen since they have an index mapping to an analyzer they don't know about. But when I attempt to update the index settings and add all the analyzer, tokenizer and filter information (via the handy upgrade recommendation via '_all/_settings?preserve_existing=true') That fails on any index because of an exception due to a mapper set to an analyzer it doesn't know about (the very analyzer I'm trying to upload to let it know about...).
Is there anyway to let my historical indices know about these custom analyzers in 5.X? Or am I looking at a reindex activity I'm definitely hopping back to my 2.X instances and adding analyzers to the index settings and templates ahead of time