Template structure (JSON/YAML) in AWS - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Identify the main sections of an AWS CloudFormation template

Which of the following lists correctly shows the main sections of a valid AWS CloudFormation template in JSON or YAML?

A Parameters, Resources, Outputs, Mappings, Conditions, Transform, Metadata

B Resources, Variables, Functions, Outputs, Conditions

C Parameters, Resources, Scripts, Outputs, Policies

D Resources, Outputs, Variables, Templates, Conditions

💡 Hint

Think about the sections that define inputs, resources, and outputs in a CloudFormation template.

A valid AWS CloudFormation template includes sections like Parameters (for inputs), Resources (for AWS resources), Outputs (for exported values), Mappings (static variables), Conditions (to control resource creation), Transform (for macros), and Metadata (additional info).

❓ Configuration

intermediate

Determine the number of resources defined in this CloudFormation snippet

Given the following JSON snippet of a CloudFormation template, how many AWS resources are defined?

{
  "Resources": {
    "MyBucket": {
      "Type": "AWS::S3::Bucket"
    },
    "MyQueue": {
      "Type": "AWS::SQS::Queue"
    },
    "MyTopic": {
      "Type": "AWS::SNS::Topic"
    }
  }
}

A 3

B 2

C 1

D 4

💡 Hint

Count the top-level keys inside the Resources section.

The Resources section contains three keys: MyBucket, MyQueue, and MyTopic, each defining one AWS resource.

❓ Architecture

advanced

Choose the correct YAML template structure for conditional resource creation

Which YAML snippet correctly uses a condition to create an AWS resource only if a parameter value is 'true'?

A

Parameters:
  CreateBucket:
    Type: String
    AllowedValues: [true, false]
Conditions:
  ShouldCreateBucket: !Equals [!Ref CreateBucket, true]
Resources:
  MyBucket:
    Type: AWS::S3::Bucket
    Condition: ShouldCreateBucket

B

Parameters:
  CreateBucket:
    Type: Boolean
Conditions:
  ShouldCreateBucket: !Equals [!Ref CreateBucket, 'true']
Resources:
  MyBucket:
    Type: AWS::S3::Bucket
    Condition: ShouldCreateBucket

C

Parameters:
  CreateBucket:
    Type: String
    AllowedValues: [yes, no]
Conditions:
  ShouldCreateBucket: !Equals [!Ref CreateBucket, 'true']
Resources:
  MyBucket:
    Type: AWS::S3::Bucket
    Condition: ShouldCreateBucket

D

Parameters:
  CreateBucket:
    Type: String
    AllowedValues: [true, false]
Conditions:
  ShouldCreateBucket: !Equals [!Ref CreateBucket, 'true']
Resources:
  MyBucket:
    Type: AWS::S3::Bucket
    Condition: ShouldCreateBucket

💡 Hint

Check the parameter type, allowed values, and how the condition compares the parameter value.

Option D correctly defines the parameter as String with allowed values 'true' and 'false', and the condition compares the parameter value as a string 'true'. The resource uses the condition to control creation.

❓ security

advanced

Identify the security risk in this CloudFormation template snippet

Review the following JSON snippet. What is the main security risk?

{
  "Resources": {
    "MyBucket": {
      "Type": "AWS::S3::Bucket",
      "Properties": {
        "BucketName": "my-public-bucket",
        "AccessControl": "PublicRead"
      }
    }
  }
}

A The bucket name is not unique, causing deployment failure

B The AccessControl property is missing, so the bucket is private by default

C The bucket is publicly readable, exposing data to anyone on the internet

D The bucket does not have versioning enabled, risking data loss

💡 Hint

Consider what 'PublicRead' means for an S3 bucket's accessibility.

Setting AccessControl to 'PublicRead' makes the bucket contents readable by anyone on the internet, which is a security risk if sensitive data is stored.

❓ service_behavior

expert

Predict the output of a CloudFormation stack update with a changed resource property

Given a CloudFormation template with an AWS::EC2::Instance resource, if you update the template to change the instance type from 't2.micro' to 't3.micro' and then update the stack, what will happen?

A CloudFormation updates the instance type in place without replacement or downtime

B CloudFormation replaces the instance with a new one of type 't3.micro', causing downtime

C CloudFormation fails the update because instance type cannot be changed

D CloudFormation creates a second instance of type 't3.micro' alongside the original

💡 Hint

Consider how CloudFormation handles changes to properties that require resource replacement.

Changing the instance type of an EC2 instance requires replacement. CloudFormation creates a new instance with the new type and deletes the old one, causing downtime during the swap.