Moving a MongoDB CMS

A publishing company runs its content management system as Docker containers on its own servers, backed by a self-managed MongoDB replica set that the team patches and backs up by hand. The company is moving to AWS and wants to stop managing both the servers and the database, without rewriting the application: it uses the MongoDB driver and query language throughout. Editors' traffic is steady through the working day, the CMS must keep running if one Availability Zone fails, and requests need a single HTTPS entry point that spreads them over the running containers and checks their health.