Good catch. If Roblox only uses consul for service discovery, things should continue to work, just slowly degrade over the hours/days. There should at least be one consul agent running on each physical hosts, and this consul agent has cache and can continue to provide service discovery functionality with stale data.

Dissecting this paragraph from the post-mortem...

> When a Roblox service wants to talk to another service, it relies on Consul to have up-to-date knowledge of the location of the service it wants to talk to.

OK.

> However, if Consul is unhealthy, servers struggle to connect.

Why? The local "client-side" consul agents running on each hosts should be the authoritative source for service discovery, not the "server-side" consul agents running on the 5 voter nodes.

> Furthermore, Nomad and Vault rely on Consul, so when Consul is unhealthy, the system cannot schedule new containers or retrieve production secrets used for authentication.

Now that's one very bad setup, similar to deploying all services in a single k8s cluster.