Since we are exploring self-healing (not self-adaptation), there's no need to deploy all the stacks we used thus far. A single service will be enough to explore what happens when a node goes down. Our cluster, formed out of t2.micro instances, would not support much more anyways.
docker service create --name test \
--replicas 10 alpine sleep 1000000
We created a service with ten replicas. Let's confirm that they are spread across the three nodes of the cluster:
docker service ps test
The output is as follows (IDs are removed for brevity):
Let's exit the cluster before we move onto a discussion how to simulate a failure of a node.
exit
We'll simulate failure of an instance by terminating it. We'll do that by executing aws ec2 terminate-instances command that requires --instance-ids argument. So, the first line of business...