Image Artist: Why do I see the error "This node is not a swarm manager" when interacting with the ImA container stack?

Problem: When interacting with the ImA container stack using the docker CLI (or the deploy.sh and undeploy.sh scripts), the following error is returned:

Error response from daemon: This node is not a swarm manager. Use "docker swarm init" or "docker swarm join" to connect this node to swarm and try again.

Solution: The Docker swarm needs to be reinitialised, like this:
 
1. Leave and clean-up the old swarm
docker swarm leave --force 
 
2. Reinitialise the swarm by executing the check_environment.sh script (found in the ImA installation directory)
./check_environment.sh 
 
3. Redeploy the stack using the undeploy.sh and deploy.sh scripts (found in the ImA installation directory)
./undeploy.sh && ./deploy.sh