Intrinsic functions
- full name Fn::Sub:, short name !Sub in YAML)
- allow the gain access to data at runtime
- can take action how things are when the template is being used to create stack
Ref & Fn::GetATT: reference a value from one logical resource or parameter in another one
Fn::Join & Fn::Split: join strings together as list or split them up ⇒ create web URL from EC2 IP
Fn::GetAZs & Fn::Select: get a list of AZ within a region where default VPS has subnets in that AZ and pick up one of these from list
Conditions (Fn::IF, And, Equals, Not & Or)
Fn::Base64: accept plaintext & output base64 text
Fn::Sub: allow you to substitute variables in the input based on runtime info (eg ${parameter/logicalresource/logicalresource.attname } )
Fn::Cidr: lets you build CIDR blocks for networking for automatic network configuration
