Dynamic created resources in CloudFormation template

Question

I am learning CloudFormation with some basic resources : VPC, subnet, EC2,.. and have some questions:
1. How to define to create 1, 2 or 3 EC2 for each time creates stacks with only one template. Each EC2 will have differences properties (EBS size, AMI,...)?
2. How to define Yes/No resources. For example, if I choose Yes in Parameter, this resources will be created. And if I choose No, this resources will not be created.
Thank you so much for your help.

Answer

1. For complex requirements like this - where you might want to loop through a set of resources and assign different properties to each one you might want to look at [CDK](https://aws.amazon.com/cdk/). For simpler requirements you might look at the [ForEach intrinsic function](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-foreach.html).
2. Have a look at [conditionally creating resources](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-conditions.html).

Answer

you can define your EC2 properties as mappings in the beginning of your cloudformation template, something like this:

Mappings:
  AMI_Mappings:
    EC2Name:
      ec21: ami21
      ec22: ami22
      ec23: ami23
      ec24: ami24
      ec25: ami25

and use Fn::ForEach intrinsic function to loop through these properties and define the EC2 resource inside the loop.

Dynamic created resources in CloudFormation template

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