Self-healing applied to services is only the beginning. It is by no means enough. The system, as it is now, is far from being autonomous. At best, it can recuperate from a few types failures. If one replica of a service goes down, Swarm will do the right thing. Even a simultaneous failure of a few replicas should not be a cause for alarm. However, self-healing applied to services by itself does not contemplate many of the common circumstances.
Let us imagine that the sizing of a cluster is done in a way that around 80 percent of CPU and memory is utilized. Such a number, more or less, provides a good balance between having too many unused resources and under-provisioning our cluster. With greater resource utilization we are running a risk that even a failure of a single node would mean that there are no available resources...
