You can change the number of worker nodes, but not the number of masters.
To change the number of worker nodes:
- From AWS CloudFormation Management page, select your DCOS cluster and click Update Stack.
- Click through to the Specify Parameters page, and you can specify new values for the PublicSlaveInstanceCount and SlaveInstanceCount.
- On the Options page, accept the defaults and click Next.
Tip: You can choose whether to rollback on failure. By default this option is set to Yes.
- On the Review page, check the acknowledgement box and then click Create.
Your new machines will take a few minutes to initialize; you can watch them in the EC2 console. The DCOS web interface will update as soon as the new nodes register.
For more information, see Creating a DCOS Cluster For Amazon Web Services