I wonder if that would be possible to temporary stop the worker VM instances so they are not running at night time when I am not working on a cluster development. So far the only way I am aware of to "stop" the instances from running is to delete the cluster itself which I don't want to do. Any suggestions are highly appreciated.
The cluster was created following steps outlined in this guide.
Edit the autoscaling group and set the instances to 0. This will shut down all worker nodes. Now you can use AWS Automation to schedule a repetitive action through automation documents that will be stopping/starting at given periods of time. You can't stop the master nodes as they are managed by AWS.
I'm just learning myself but this might help. If you have eksctl installed, you can use it from the command line to scale your cluster. I scale mine down to the min size when I'm not using it:
eksctl get cluster
eksctl get nodegroup --cluster CLUSTERNAME
eksctl scale nodegroup --cluster CLUSTERNAME --name NODEGROUPNAME --nodes NEWSIZE