CloudFormation

Introduction

• Declarative language for deploying resources in AWS
• YAML or JSON
• CloudFormation templates can be visualized using Application Composer

Example

---
Resources:
  MyInstance:
    Type: AWS::EC2::Instance
    Properties:
      AvailabilityZone: us-east-1a
      ImageId: ami-0a3c3a20c09d6f377
      InstanceType: t2.micro

CloudFormation Template Sections

• Resources

  • The only required section in a template
  • The resources section represent the AWS components that the CF template will deploy
  • Resource type identifiers are in this format:
    • service-provider::service-name::data-type-name

• Parameters

  • Provide input to your CF templates

• Mappings

  • Fixed variables in your CF template used to differentiate between different environment like dev vs prod, regions, AMI types, etc.

  • To access values in a map, use Fn::FindInMap:

        {
          ...
          "Mappings" : {
            "RegionMap" : {
              "us-east-1" : {
                "HVM64" : "ami-0ff8a91507f77f867", "HVMG2" : "ami-0a584ac55a7631c0c"
              },
              "us-west-1" : {
                "HVM64" : "ami-0bdb828fd58c52235", "HVMG2" : "ami-066ee5fd4a9ef77f1"
              },
              "eu-west-1" : {
                "HVM64" : "ami-047bb4163c506cd98", "HVMG2" : "ami-0a7c483d527806435"
              },
              "ap-southeast-1" : {
                "HVM64" : "ami-08569b978cc4dfa10", "HVMG2" : "ami-0be9df32ae9f92309"
              },
              "ap-northeast-1" : {
                "HVM64" : "ami-06cd52961ce9f0d85", "HVMG2" : "ami-053cdd503598e4a9d"
              }
            }
          },
    
          "Resources" : {
            "myEC2Instance" : {
              "Type" : "AWS::EC2::Instance",
              "Properties" : {
                "ImageId" : {
                  "Fn::FindInMap" : [
                    "RegionMap",
                    {
                      "Ref" : "AWS::Region"
                    },
                    "HVM64"
                  ]
                },
                "InstanceType" : "m1.small"
              }
            }
          }
        }
    

• Outputs

  • Optional
  • Output values can be referenced in other stacks
  • Use FN:ImportValue

• Conditions

  • Control the creation of resources or outputs based on a condition

Intrinsic Functions

• Fn::Ref - Get a references to a value of a paremeter, physical Id of a resource, etc.
• Fn::GetAtt - Get attributes from a resource
• Fn::FindInMap - Retrieve a value from a map
• Fn::ImportValue - Import an output value from another template
• Fn::Base64 - Convert a value to Base64 inside a template
• Condition Functions (Fn::If, Fn::Not, Fn::Equals, etc.)
• etc….

Service Roles

• IAM roles that allow CloudFormation to create/update/delete stack resources