强一致 最终一致
Frequently Asked Questions - Consul by HashiCorp https://www.consul.io/docs/faq.html
Q: Is Consul eventually or strongly consistent?
Consul has two important subsystems, the service catalog and the gossip protocol. The service catalog stores all the nodes, service instances, health check data, ACLs, and KV information. It is strongly consistent, and replicated using the consensus protocol.
The gossip protocol is used to track which nodes are part of the cluster and to detect a node or agent failure. This information is eventually consistent by nature. When the servers detects a change in membership, or receive a health update, they update the service catalog appropriately.
Because of this split, the answer to the question is subtle. Almost all client APIs interact with the service catalog and are strongly consistent. Updates to the catalog may come via the gossip protocol which is eventually consistent, meaning the current state of the catalog can lag behind until the state is reconciled.