139 karma · joined November 1, 2021
Also, as long running services crash or reboot naturally they need to be rescheduled or else your cluster slowly dies, and as your cluster size increases the mtbf decreases and the need to reschedule workloads continually increases.
Vault is secrets and management. Put secret strings in, get secret strings out (if permitted). Most apps need secrets of some type, and vault is normally discovered via consul.
Nomad is an application/workload scheduler. You tell it what you need to run and what their memory/cpu requirements are and it finds a space in your physical infrastructure to run that. The apps it runs normally needs secrets from vault and communicate with services discovered via consul.
They all are well integrated and build off of each other, kind of like layers an onion where your app services are the outer layer of the onion. Consul failing this badly is like the core of the onion going rotten. There’s not much saving it at that point, you need to grow a new onion from the inside out, but that takes time.
Furthermore, the services were down for long enough that the asset caches went fully cold, so spinning back up to 100% capacity would put far more load than usual on the servers meaning recovery needed to be a very slow incremental rollout to warm them.
Messy situation all around, but if you want the real root cause pay attention to the consul change log over the next few weeks I’d say.