CloudFormation Overview¶

Infrastructure as Code¶

Currently, we have been doing a lot of manual work
All this manual work will be very tough to reproduce:
- In another region
- In another AWS account
- Within the same region if everything was deleted
Wouldn't it be great, if all our infrastructure was... code?
That code would be deployed and create / update / delete our infrastructure.

CloudFormation is a declarative way of outlining our 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 EC2 machines using this security group
- I want two Elastic IPs for these EC2 machines
- I want an S3 bucket
- I want a load balancer (ELB) if front of these machines
Then CloudFormation creates those for you, in the right order, with the exact configuration you specify.

Infrastructure as code
- No resources are manually creasted, 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 resource within the stack is tagged with an identifier so you can easily see how much a stack costs you
- You can estimate the costs of your resources using CloudFormation template
- Savings strategy: In Dev, you could automate deletion of templates at 5pm and recreate 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 pps, and many layers. Ex: VPC stacks, network stacks, App stacks.
Don't re-invent the wheel
- Leverage existing templates on the web!
- Leverage the documentation!

Templates have to be uploaded in 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 that was created by CloudFormation

Manual way:
- Editing templates in the cloudformation designer
- using the console to input parameters
Automated way:
- Editing templates in a YAML file
- Using the AWS CLI to deploy the templates
- Recommended way when you fully want to automate your flow