You have heard about user data in AWS or Terraform. What is it?
Answer for AWS
Generally it is a customization that the account owner configured to apply to an EC-2 instance when it first launches. It is either a shell script or a cloud-init directive that is used when an EC-2 instance is launched (according to
Shell scripts that the customer provides are self-explanatory. The cloud-init directives are for SSH key configuration (according to
Answer for Terraform
It is one or more bash commands that run when a server is initially created and booted (according to page 14 of Terraform Up & Running).