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Introduction to CloudFormation

  • CloudFormation is a service that allows you to manager, configure, and provision your AWS infrastructure as code.
  • Resources are defined using a CloudFormation template.
  • CloudFormation interprets the template and makes the appropriate API calls to create the resources you have defined.
  • Supports YAML or JSON

Benefits of CloudFormation

  • Infrastructure is provisioned consistently, with fewer mistakes
  • Less time and effort than configuring things manually
  • You can version control and peer review your templates
  • Free to use (charged for what you create)
  • Can be used to manage updates and dependencies
  • Can be used to rollback and delete the entire stack as well.

CloudFormation Template

  • YAML or JSON template used to describe the endstate of infrastructure you are either provisioning or changing.
  • After creating the template, you upload it to CloudFormation using S3.
  • CloudFormation reads the template and makes the API calls on your behalf.
  • The resulting resources are called a stack.

Example Template

AWSTemplateFormatVersion: "2010-09-09"
Description: "Template to create an EC2 instance"
Metadata:
  Instances:
  Description: "Web Server Instance"
Parameters: #input values
  EnvType:
    Description: "Environment type"
    Type: String
    AllowedValues:
      - prod
      - test
Conditions:
  CreateProdResources: !Equals [ !Ref EnvType, prod ]
Mappings: #e.g. set values based on region
  RegionMap:
    eu-west-1:
    "ami":"ami-394534954395e"
Transform: # include snippets of code outside the main template
  Name: 'AWS::Include'
  Parameters:
    Location: "s3://MyAmazonS3BucketName/MyFileName.yaml"
Resources: # the AWS resources you are deploying
  EC2Instance:
    Type: AWS::EC2::Instance
    Properties:
      InstanceType: t2.micro
      ImageId: ami-Odb1d6c9349334334c"
Outputs:
  InstanceID:
    Description: The Instance ID
    Value: !Ref EC2Instance
  • Resources is the only mandatory section of the CloudFormation template

  • Remember that the Transform section is used to reference additional code stored in S3, allowing for code re-use, e.g. for Lambda code or template snippets / reusale pieces of CloudFormation code.

  • CloudFormation allows you to manage, configure, and provision AWS infrastructure as code (YAML / JSON).

  • Remember the main sections in the Cloudformation Template:
    • Parameters: input custom values
    • Conditions: e.g. provision resources based on environment
    • Resources: Mandatory; the AWS resources to create
    • Mappigs: Create custom mappings like Region: AMI
    • Transforms: Reference code located in S3 e.g. Lambda code or reusable snippets of CloudFormation code.