We had a situation like that once because of circular dependencies; services that needed another service to start. “How is that possible?” you ask. Code reviews

We had a situation like that once because of circular dependencies; services that needed another service to start. “How is that possible?” you ask. Code reviews; “take that code out and get the data from an existing service.” We hard-coded data into a base service, pushed it to production, restarted services that depended on it, then services that depended on those services, etc.