leave docker swarm, but leave services running

Question

是否可以让docker swarm节点离开swarm，但在成为swarm成员的同时保持启动运行的服务？

Answer 1

Short answer: don't try to do that.

This would be against the design of swarm mode. For the same reason that docker disables the live-restore functionality when you have swarm mode, you shouldn't be able to keep services running when a node leaves the swarm cluster. The logic behind both decisions is when swarm mode detects that the target state of the service doesn't match the current state, it will do what it can to achieve that target state.

With the live-restore, docker would normally leave containers running when the daemon is stopped, and restore those containers to the docker daemon when the daemon restarts. And similarly, if the containers continued to run when the node leaves the swarm, from the view of the swarm manager, the result would be the same, containers running that the manager has no way to track the current state.

Since the current state cannot be tracked in those scenarios, docker errors on the side of stopping the container when it gracefully stops or leaves the swarm. The scenario where containers will continue to run is during an ungraceful disconnection from the swarm manager(s). In that scenario, the worker doesn't know if only it is down and the workload has been rescheduled elsewhere, or if only the manager is down, and stopping the containers would turn a small outage into a big one, so docker errors on the side of leaving the containers running when the disconnect is uncontrolled.