The core Shopify app has remained a Rails monolith, but we also have hundreds of other Rails apps across the organization. These are not microservices, but domain-specific apps: Shipping (talks with various shipping providers), Identity (single sign on across all Shopify stores), and App Store to name a few. Managing a hundred apps and keeping them up to date with security updates can be tough, so we've developed ServicesDB, an internal app that keeps track of all production services and helps developers to make sure that they don't miss anything important.
ServicesDB keeps a checklist for each app: ownership, uptime, logs, on-call rotation, exception reporting, and gem security updates. If there are problems with any of those, ServicesDB opens a GitHub issue and pings owners of the app to ask them to address it. ServicesDB also makes it easy to query the infrastructure and answer questions like, “How many apps are on Rails 4.2? How many apps are using an outdated version of gem X? Which apps are calling this service?”.