Related: CloudFormation, EC2

AWS::CloudFormation::Init

Special procedure-script included in every Amazon Linux image

cfn-init – the script name, has simple configuration mgmt system

Procedural (as User Data) – customer provides the config details in form of base64.
Desired state (cfn-init) – customer describes what needs to be done on instance.
Package manipulation with version awareness, system user&group, download sources, file creation and commands and services.
Provided with directives via Metadata or AWS::CloudFormation::Init

CF Template has EC2 instance configuration as AWS::EC2:Instance with UserData which lauches cfn-init and provides it with stack+region etc

CFN Creation Policy and Signal

We can make CF aware of Instance deployment status.
Creation Policy included in CF template will wait for Signal.