I suspect most business logic can handle 25ms for authz and that’s the right trade off. I think Google’s Zanzibar is also centralized but leverages extreme caching to get lower latencies?
I work on an IAM system that is sub-ms p99 for our authz checks, with policies and keys pushed to each network edge instead of running a centralized system. The biggest perf hits are crypto verification and logging to the fs. We fail-closed to last known policy state when we have partitions, data loss would imply the application service or datastore proxy is lost. We measure policy deploy times in minutes though, and it’s eventually consistent.
I work on an IAM system that is sub-ms p99 for our authz checks, with policies and keys pushed to each network edge instead of running a centralized system. The biggest perf hits are crypto verification and logging to the fs. We fail-closed to last known policy state when we have partitions, data loss would imply the application service or datastore proxy is lost. We measure policy deploy times in minutes though, and it’s eventually consistent.