https://slack.engineering/slacks-migration-to-a-cellular-architecture/ [slack.engineering]
All services are present in all AZs, but each service only communicates with services within its AZ. Failure of a system within one AZ is contained within that AZ, and we may dynamically route traffic away to avoid those failures simply by redirecting at the frontend
https://slack.engineering/slacks-migration-to-a-cellular-architecture/ [slack.engineering]