In the two days, the Docker Swarm Mode will be added to the new management node to report the following errors (as seen in the /var/log/messages file):
Handler for POST /v1.37/swarm/join returned error: manager stopped: can’t initialize raft node: rpc error: code = Unavailable desc = grpc: the connection is unavailable
Search keywords in stackoverflow，A survey found a post:
It means not to use an agent.
The NO_PROXY in the swarm set up the IP node of manager node. The problem is finally solved.