https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-ec2-keypair.html

Based on this documentation, you should be able to create a new key pair when launching an instance instead of creating one before hand and referencing it through parameters.

AWS even provides an example:

Resources:
  NewKeyPair:
    Type: 'AWS::EC2::KeyPair'
    Properties:
      KeyName: MyKeyPair
  Ec2Instance:
    Type: 'AWS::EC2::Instance'
    Properties:
      ImageId: ami-02b92c281a4d3dc79
      KeyName: !Ref NewKeyPair

The template is valid, but after I launch the stack I get this error:

NewKeyPair - Resource handler returned message: "null" (RequestToken: 6068026b-63b2-c71b-6cbb-f76f09fe599e, HandlerErrorCode: AlreadyExists)

EC2-SecurityKey - The following resource(s) failed to create: [NewKeyPair]. Rollback requested by user.

Anyone know why this rollback occurs and if I am missing something?

CodePudding user response：

The error means that you already have a key pair which has the same name as !Ref NewKeyPair. You have to ensure that your new key pair has new name, or delete pre-existing key pair.

CodePudding user response：

Check Your Keypairs from the ec2 console this error is about you already created "MyKeyPair" named key that's why this error is coming. if you want to create a key pair change a keypair name in this script or delete the old key pair named "MyKeyPair". this might be solve this error