stack-designer

Stack Designer

Quick Start

Design well-organized CloudFormation stacks with proper resource grouping, parameters, outputs, and cross-stack references.

Instructions

Step 1: Identify stack boundaries

Determine how to organize resources into stacks:

By lifecycle:

• Resources that change together should be in the same stack
• Separate frequently updated resources from stable infrastructure
• Group by deployment frequency

By ownership:

• Network stack (VPC, subnets, route tables)
• Security stack (security groups, IAM roles)
• Application stack (EC2, ECS, Lambda)
• Data stack (RDS, DynamoDB, S3)

By environment:

• Separate dev, staging, production stacks
• Use parameters for environment-specific values
• Share common resources via cross-stack references

Step 2: Design stack structure

Simple stack (single template):

AWSTemplateFormatVersion: '2010-09-09'
Description: Simple web application stack

Parameters:
  EnvironmentName:
    Type: String
    Default: dev
    AllowedValues: [dev, staging, prod]
  
  InstanceType:
    Type: String
    Default: t3.micro
    AllowedValues: [t3.micro, t3.small, t3.medium]

Resources:
  WebServer:
    Type: AWS::EC2::Instance
    Properties:
      InstanceType: !Ref InstanceType
      ImageId: !Sub '{{resolve:ssm:/aws/service/ami-amazon-linux-latest/amzn2-ami-hvm-x86_64-gp2}}'
      Tags:
        - Key: Environment
          Value: !Ref EnvironmentName

Outputs:
  InstanceId:
    Description: EC2 instance ID
    Value: !Ref WebServer
    Export:
      Name: !Sub '${AWS::StackName}-InstanceId'

Multi-stack architecture:

Root Stack
├── Network Stack (VPC, subnets)
├── Security Stack (security groups, IAM)
├── Database Stack (RDS)
└── Application Stack (EC2, ALB)

Step 3: Define parameters

Parameter best practices:

Parameters:
  # Use descriptive names
  DatabaseInstanceClass:
    Type: String
    Default: db.t3.micro
    AllowedValues:
      - db.t3.micro
      - db.t3.small
      - db.t3.medium
    Description: RDS instance class
  
  # Validate input
  DatabaseName:
    Type: String
    MinLength: 1
    MaxLength: 64
    AllowedPattern: '[a-zA-Z][a-zA-Z0-9]*'
    ConstraintDescription: Must begin with letter, contain only alphanumeric
  
  # Use AWS-specific types
  VpcId:
    Type: AWS::EC2::VPC::Id
    Description: VPC for resources
  
  SubnetIds:
    Type: List<AWS::EC2::Subnet::Id>
    Description: Subnets for resources
  
  # Sensitive values from SSM
  DatabasePassword:
    Type: AWS::SSM::Parameter::Value<String>
    Default: /myapp/database/password
    NoEcho: true