CloudFormation

Question 1

What is CloudFormation?

Answer 1

• Infrastructure as Code
• Code that can be deployed and is written to create / update / delete infrastructure

Question 2

Is there a cost for using CloudFormation?

Answer 2

No. Only the underlying services.

Question 3

High Level - How does CloudFormation work?

Answer 3

• Templates have to be uploaded in S3 and then referenced in CloudFormation.
• To update a template, a new version must be uploaded to AWS (cannot edit existing one directly).

Question 4

What are the 2 main ways to deploy CloudFormation templates?

Answer 4

• Manually
• Automated (recommended)

Question 5

Describe manual deploys in CloudFormation

Answer 5

• Edit templates in the CloudFormation designer
• Use the console to input parameters etc.

Question 6

Describe the high level overview of deploying CloudFormation through automation.

Answer 6

• Edit templates in a YAML file.
• Use the AWS CLI to deploy the templates.
• Recommended way in order to fully automate flow.

Question 7

List the 6 main building blocks for CloudFormation.

Answer 7

1. Resources (Required)
2. Parameters
3. Mappings
4. Outputs
5. Conditionals
6. Metadata

Question 8

The exam will not expect you to write CloudFormation templates, but it will expect you to be able to READ CloudFormation templates. What language should you be familar with so that you can read and understand CloudFormation?

Answer 8

YAML

Question 9

Can Resources be dynamically created using CloudFormation?

Answer 9

No. Resources in the CloudFormation Template must be declared.

Question 10

Is every AWS resource supported through CloudFormation.

Answer 10

No, but almost. Mostly smaller services that are not yet addressed and you can work around that using AWS Lambda Custom Resources.

Question 11

What are CloudFormation parameters?

Answer 11

• Parameters are a way to provide inputs to your AWS CloudFormation templates.
• Parameters are extremely powerful, controlled, and can prevent errors from happening in your templates thats to types.

Question 12

When should you use CloudFormation parameters?

Answer 12

• If the CloudFormation resource is likely to change in the future.
• By making a parameter you will not have to re-load a template to change its content.

Question 13

How do you reference a parameter in CloudFormation?

Answer 13

• The Fn::Ref function can be leverage to reference parameters.
  
  • The shorthand for this in YAML is !Ref
• Parameters can be referenced anywhere in the template.

Question 14

How can you get the account ID using a CloudFormation template?

Answer 14

• CloudFormation has something called pseudo parameters.
• These can be used at anytime and are enabled by default.
• One of these pseudo parameters in AWS::AccountId

Question 15

What are CloudFormation Mappings?

Answer 15

• Mapping are fixed variables with the CloudFormation template.
• Handy to differentiate between different environments (dev vs prod), regions, AMI types etc.
• All values are hardcoded in the template.

Question 16

What is the difference between CloudFormation parameters & mappings?

Answer 16

Use Mapping when you know values in advanced and reosurces will most likely NOT change. Those values can be turned into variables (region, AMI, enviroment etc. ).

Use Parameters when a resource configuration is likely to change in the future.

Question 17

What happens if you delete a stack created by CloudFormation?

Answer 17

Deleting a stack deletes every single artifact that was created by
CloudFormation.

Question 18

How are CloudFormation stacks identified?

Answer 18

Stacks are identified by a name.

Question 19

What are CloudFormation outputs?

Answer 19

• The outputs section in a CloudFormation template declares optional outputs that must first be exported and then can be imported into other stacks.
• Allows for collaboration across stacks.

Question 20

What happens if you delete a stack that has declared exported outputs?

Answer 20

That stack cannot be deleted as long as exported outputs are being used in other stacks.

Question 21

What is a CloudFormation Cross Stack Reference?

Answer 21

When a stack references the output(s) of another stack.

Question 22

How are CloudFormation outputs imported into another stack?

Answer 22

• Fn::ImportValue
• In YAML this is : !ImportValue [Value Variable Name]

Question 23

How are conditions used in CloudFormation?

Answer 23

• Conditions are used to control the create of resources or outputs.
• Example: Conditions can be based on Environment, Region etc.

Question 24

Hoe are conditions defined in CloudFormation?

Answer 24

There is a conditions section the YAML file that can use any common logical operators.

Question 25

What are the five conditional (logical) operators that can be used in CloudFormation?

Answer 25

* Fn::And * Fn::Equals * Fn::If * Fn::Not * Fn::Or

Question 26

Other then CloudFormation conditional values, what are six Instrinic functions to know?

Answer 26

All six are prepended with Fn:: * Ref * GetAtt * FindInMap * ImportValue * Join * Sub

Question 27

Fn::Ref

Answer 27

* References a parameter (returns the value of the paramter) or * references a resource (returns the physical ID of the underlying resource. * YAML = !Ref

Question 28

Fn::GetAtt

Answer 28

* Returns a value for a specified attribute of the defined type. * Example for EC2 you can to Fn::GetAtt AvailabilityZone

Question 29

Fn::FindInMap

Answer 29

* Accesses mapped values - returns a named value from a specific key * YAML = !FindInMap

Question 30

Fn::ImportValue

Answer 30

* Import values are values that have been exported from another CloudFormation template. * YAML = !ImportValues

Question 31

Fn::Join

Answer 31

Join values with a delimiter **Example:** !Join [":" , [a,b,c] ] returns 'a:b:c'

Question 32

Fn::Sub

Answer 32

* Used to substitute variable from text. * Allows you to fully customize your templates. * YAML = !Sub

Question 33

What is a cross stack and when are they useful?

Answer 33

* Cross-stack references let you use a layered or service-oriented architecture. Instead of including all resources in a single stack, you create related AWS resources in separate stacks; then you can refer to required resource outputs from other stacks.. (Example, VPC stack, ELB Stack etc.). * Helpful when stacks have different lifecycles. * Use outputs export and importValue.

Question 34

In CloudFormation, what is a nested stack, and when are they useful?

Answer 34

* Nested stacks are stacks created as part of other stacks. * You create a nested stack within another stack by using the AWS::CloudFormation::Stack resource. * Helpful when components must be reused

Question 35

In CloudFormation, what are StackSets?

Answer 35

* StackSets all you to create, update, or delete stacks **across multiple accounts and regions** with a single operation. * When you update a stack set, **all** associated stack instances are updated throughout **all accounts and regions**.