Never underestimate the power of a zero-network-hop abstraction over f(feature_name, context). And context can be extremely tailored to your niche: specific inventory, from a specific supplier, for a specific user of a specific B2B client of a specific business model subtype, who should or shouldn’t see certain features on that specific inventory at certain times. When you can write your own logic, and just run this…
For me feature flags go along with trunk based development to enable features in QA settings, but not on PROD yet, for PO/PM testing. Trunk based development allows for fast/easy devops, without complicated branching strategies.
Application configuration is, for me, part of the application and has the business context for customizing the application accordingly. Not sure if there are specific frameworks/tools out there. But one should clearly distinguish these two.