The kops create cluster command, which we used to create the cluster configuration, doesn't actually create the cluster itself and launch the EC2 instances; instead, it creates the configuration file in our S3 bucket.

After creating the configuration file, you can make changes to the configuration using the kops edit cluster command. 

You can separately edit your node instance groups using the following command:

$ kops edit ig nodes 
$ kops edit ig master-us-east-1a

The config file is called from the S3 bucket's state store location. If you prefer a different editor you can, for example, set $KUBE_EDITOR=nano to change it.