At a practical level, for our mature in-house codebase a switch to microservices is not necessary or cost effective. This year, however, has seen Stephan Hagemann’s ‘Component Based Rails Applications’ ebook published (endorsed) as a softback by Addison Wesley and a very similar approach embraced by Shopify. Our own internal codebase remains ~60% gemified from 2017 in a simple layered architecture while we have focused on consistently packaging business logic using interactors (service objects) for both foreground and background processes.
New gems (to us) used this year included roxml, and replacing the unmaintained god process monitor with eye. On the open source side I stepped back from contributing to ActiveAdmin and published instead a couple of API clients for AmEx and PayPal.