CloudFormation¶

What is CloudFormation¶

• CloudFormation is a [[declarative]] way of outlining your AWS [[Infrastructure]], for any resources (most of them are supported).
• For example, within a CloudFormation template, you say:
  • I want a security group
  • I want two AWS EC2 machines using this security group
  • I want two Elastic IPs for these AWS EC2 machines
  • I want an AWS S3 Bucket
  • I want a [[Elastic Load Balancer]] in front of these machines
• Then CloudFormation creates those for you, in the right order, with the exact configuration you specify.

Benefits of AWS CloudFormation¶

• Infrastructure as code
  • No resources are manually created, which is excellent for control
  • The code can be [[version controlled]] for example, using [[git]]
  • Changes to the [[infrastructure]] are [[reviewed]] through code
• Cost
  • Each resources within the stack are tagged with an identifier so you can easily see how much stack costs you
  • You can estimate the costs of your resources using the [[CloudFormation template]]
  • [[Savings strategy]]: in dev, you could make automation that deletes templates at 5pm and recreates them at 8am safely.
• Productivity
  • Ability to destroy and re-create an infrastructure on the cloud on the fly
  • Automated generation of [[Diagram]] for your templates
  • [[Declarative programming]] (no need to figure out ordering and orchestration)
• Separation of concern - create many stacks for many apps, and many layers
  • [[VPC stack]]s
  • [[Network stack]]s
  • [[App stack]]s
• Don't re-invent the wheel
  • Leverage existing templates on the web!
  • Leverage [[documentation]]

How CloudFormation works¶

• Templates have to be uploaded in AWS S3 and then referenced in CloudFormation
• To update a template, we can't edit previous ones. We have to re-upload a new version of the template to AWS
• Stacks are identified by a name
• Deleting a stack deletes every single [[artifact]] was created by CloudFormation

Deploying CloudFormation templates¶

• Manual way:
  • Editing templates in the [[CloudFormation Designer]]
  • Using the console to [[input parameter]]s, etc
• Automated way
  • Editing templates in a [[YAML]] file
  • Using the [[AWS CLI]] to [[deploy]] the templates

Templates components¶

• Resources components
  • Resources: your AWS resources declared in the template (mandatory)
  • Parameters: the [[dynamic input]]s for your template
  • Mappings: the [[static variable]]s for your template
  • Outputs: [[Reference]]s to what has been created
  • Conditionals: List of [[condition]]s to perform resource creation
  • [[Metadata]]
• Templates helpers
  • [[Reference]]s
  • [[Function]]s

Hands On¶

When creating a new stack, you can choose between 3 options: - Upload your template - Use a sample template - Design your template in a [[GUI]] way