What's the particular issue you're running into? A few general notes though: - Uptime SLAs will probably be very high for such a central service, so HA backing

What's the particular issue you're running into? A few general notes though: - Uptime SLAs will probably be very high for such a central service, so HA backing database choices and / or read-only replicas. For authn & authz caching session tokens / API keys / policy decisions / ... is fairly essential to not overload your DB and keep latency down to acceptable levels. - Work out what latency budget you can afford given that every user action is going to have to go through this service, possibly multiple times. Stop the world garbage collected languages probably aren't ideal here. Judicious use of caching goes a long way. - Have load shedding / circuit breaking / per-service quota mechanisms in place to prevent issues cascading around your systems. Exponential back-off is a lifesaver. - Have good integration tests to catch regressions (functionality & performance), roll-out / roll-back mechanisms to catch the ones you miss. Test these with known-bad changes every once in a while. I've recently been doing a load of development on similar systems, so happy to give my two cents - email is in profile if you'd prefer. The two SRE books are a worthwhile read.