If you have used Ubuntu images on AWS, you might have noticed that the default username of the user on the instance is ‘ubuntu’. And the hostname is dynamically generated according to the public IP. Both of these can be changed using cloud-config supported on Ubuntu images – the config has to be provided in the User Data section in Advanced on the Configure Instance tab.
YAML configuration to change the parameters:
A lot more things are possible using the cloud-config method and it is supported on other operating system images as well such as CentOS. Take a look at Cloud config examples.