Templates

Resources

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Resources:
  MyEC2Instance:
    Type: AWS::EC2::Instance
    Properties:
      ImageId: ami-a4c7edb2
      InstanceType: t2.micro

Parameters

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Parameters:
  MyInstanceType:
    Type: String

Resources:
  MyEC2Instance:
    Type: AWS::EC2::Instance
    Properties:
      ImageId: ami-a4c7edb2
      InstanceType: !Ref MyInstanceType
  • Pseudo Parameters
    • AWS::AccountId
    • AWS::NotificationARNs
    • AWS::NoValue
    • AWS::Region
    • AWS::StackId
    • AWS::StackName

Mappings

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Mappings:
  MyRegionImageId:
    us-east-1:
      '32': ami-6411e20d
      '64': ami-7a11e213
    us-west-1:
      '32': ami-c9c7978c
      '64': ami-cfc7978a

Resources:
  MyEC2Instance:
    Type: AWS::EC2::Instance
    Properties:
      ImageId: !FindInMap 
        - MyRegionImageId
        - !Ref AWS::Region
        - '32'
      InstanceType: t2.micro

Outputs

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# Stack 1
Resources:
  MyEC2Instance:
    Type: AWS::EC2::Instance
    Properties:
      ImageId: ami-a4c7edb2
      InstanceType: t2.micro

Outputs:
  Value: !Ref MyEC2Instance
  Export:
    Name: MyEC2InstanceOutput
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# Stack 2
Resources:
  Type: AWS::EC2::EIP
  Properties:
    InstanceId: !ImportValue MyEC2InstanceOutput

Conditions

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Conditions:
  CreateEC2Instance: !Equals
    - !Ref AWS::Region
    - us-east-1

Resources:
  MyEC2Instance:
    Type: AWS::EC2::Instance
    Condition: CreateEC2Instance
    Properties:
      ImageId: ami-a4c7edb2
      InstanceType: t2.micro

Intrinsic Functions

Fn::Ref

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# Ref the resource id
!Ref MyEC2Instance

Fn::GetAtt

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# Get an attribute of a resource
!GetAtt MyEC2Instance.AvailabilityZone

Fn::FindInMap

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# Find a value from a mapping
!FindInMap
  - MyRegionImageId
  - !Ref AWS::Region
  - '32'

Fn::ImportValue

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# Get a exported value from other templates
!ImportValue MyEC2InstanceOutput

Fn::Join

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# Join values into a string
!Join 
  - ::
  - - AWS
    - Region

Fn::Sub

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# substitute
!Sub 
  - ${hostname}.${domain}
  - hostname: aws
    domain: amazon.com

Condition Functions

  • Fn::And
  • Fn::Equals
  • Fn::If
  • Fn::Not
  • Fn::Or

Others

Rollback

  • If stack creation failed, it will rollback to the previous version automatically
    • Can be disabled
    • If no previous, it will be deleted

Drift

  • Detect if the resources created by CloudFormation is modified (configured different from the CloudFormation template)