Assign way more replicas than you have of memory on all nodes and watch the Swarm crash which can easily reproduce in a small VMfor testing.
root@Deb11Docker01:~# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAM........
The error below can be caused by a gateway that is unpingable:
docker swarm join --token SWMTKN-1-1kogg8da68gtb1j7ezaddowyy9s0an5s9tue758o20k18liskw-5h3f61hrrmv3u6agshvbtcklf 172.16.1.80:2377
Error response from daemon: manager stopped: can't initialize raft node: rpc error: code = Unknown desc = could not connect to prospective new cluster member using its advertised address: rpc error: code = DeadlineExceeded desc = context deadline exceeded........
A lot of companies are unsure which solution to choose and many may not be aware of Docker Swarm as an alternative to Kubernetes. One thing that many Sysadmins find is that Docker Swarm is simply easier, quicker to setup and maintain by far than Kubernetes.........
If you have swarm services and dockerd is creating a high load even with the containers just being idle, the easiest solution is to upgrade to a newer docker version.
For example an identical config of 3 nodes, with Redis 5 with 30 replicas produces a load of about 1.45 in Debian 10 with Docker18.09.1
If I create the same setup on Debian 11, with Docker 20.10.5+dfsg1 then the CPU usage is low.
One other difference I wondered is the kernel. In my test setup........
The Best Docker Tutorial for Beginners
We quickly explain the basic Docker concepts and show you how to do the most common tasks from starting your first container, to making custom images, a Docker Swarm Cluster Tutorial, docker compose and Docker buildfiles.........