Template structure (JSON/YAML) in AWS - Mini Project: Build & Apply

AWS CloudFormation Template Structure

📖 Scenario: You are setting up a simple AWS CloudFormation template to create a basic infrastructure stack.This template will help you understand how AWS resources are defined and organized using JSON or YAML format.

🎯 Goal: Build a valid AWS CloudFormation template structure in JSON format with the essential sections: AWSTemplateFormatVersion, Description, Resources, and Outputs.

📋 What You'll Learn

Create a JSON CloudFormation template with the exact key names and structure.

Include AWSTemplateFormatVersion set to "2010-09-09".

Add a Description with the text "Basic CloudFormation template structure".

Define an empty Resources object.

Define an empty Outputs object.

💡 Why This Matters

🌍 Real World

CloudFormation templates are used to automate AWS infrastructure setup, making deployments repeatable and consistent.

💼 Career

Understanding CloudFormation template structure is essential for cloud engineers and developers working with AWS infrastructure as code.

1

Create the basic template version and description

Create a JSON object with the key AWSTemplateFormatVersion set to "2010-09-09" and the key Description set to "Basic CloudFormation template structure".

AWS

{
  // Your code here
}

Hint

Use double quotes for JSON keys and string values.

2

Add an empty Resources section

Add a key Resources with an empty JSON object {} to the existing JSON template.

AWS

{
  "AWSTemplateFormatVersion": "2010-09-09",
  "Description": "Basic CloudFormation template structure",
  // Your code here
}

Hint

The Resources key holds all AWS resources you want to create.

3

Add an empty Outputs section

Add a key Outputs with an empty JSON object {} to the existing JSON template after the Resources key.

AWS

{
  "AWSTemplateFormatVersion": "2010-09-09",
  "Description": "Basic CloudFormation template structure",
  "Resources": {},
  // Your code here
}

Hint

The Outputs section is used to declare values you want to see after stack creation.

4

Complete the CloudFormation template structure

Ensure the JSON template includes AWSTemplateFormatVersion, Description, Resources, and Outputs keys exactly as specified, with Resources and Outputs as empty objects.

AWS

{
  "AWSTemplateFormatVersion": "2010-09-09",
  "Description": "Basic CloudFormation template structure",
  "Resources": {},
  "Outputs": {}
  // Your code here
}

Hint

Review the entire JSON structure to confirm all keys are present and correctly formatted.

Practice

1. What is the main purpose of a cloud template written in JSON or YAML?

easy

A. To manually configure cloud resources one by one

B. To write application code for cloud functions

C. To monitor cloud resource usage in real-time

D. To describe and set up cloud resources automatically

Solution

1. Step 1: Understand what a cloud template does

   A cloud template is a file that describes cloud resources and how to create them automatically.

2. Step 2: Compare options with this purpose

   Only To describe and set up cloud resources automatically matches this description; others describe different tasks.

3. Final Answer:

   To describe and set up cloud resources automatically -> Option D

4. Quick Check:

   Cloud templates automate resource setup = D [OK]

Hint: Templates automate resource setup, not manual or monitoring tasks [OK]

Common Mistakes:

• Confusing templates with monitoring tools
• Thinking templates are for writing application code
• Assuming templates require manual resource setup

2. Which of the following is the correct top-level section name in an AWS CloudFormation JSON template?

easy

A. Resources

B. Scripts

C. Functions

D. Commands

Solution

1. Step 1: Recall AWS CloudFormation template structure

   The main sections include Parameters, Resources, Outputs, etc. 'Resources' defines the cloud resources.

2. Step 2: Identify valid section names

   Only 'Resources' is a valid top-level section; others are not used in CloudFormation templates.

3. Final Answer:

   Resources -> Option A

4. Quick Check:

   Resources section defines cloud resources = C [OK]

Hint: Remember: Resources section always defines cloud items [OK]

Common Mistakes:

• Using non-existent sections like Scripts or Commands
• Confusing function code with template sections
• Mixing up template sections with programming terms

3. Given this snippet of a CloudFormation JSON template:

{
  "Resources": {
    "MyBucket": {
      "Type": "AWS::S3::Bucket"
    }
  }
}

What resource will this template create?

medium

A. An EC2 virtual server

B. An S3 storage bucket

C. A Lambda function

D. A VPC network

Solution

1. Step 1: Read the resource type in the template

   The resource type is "AWS::S3::Bucket", which means an S3 storage bucket.

2. Step 2: Match resource type to options

   Only An S3 storage bucket matches the S3 bucket resource type.

3. Final Answer:

   An S3 storage bucket -> Option B

4. Quick Check:

   "AWS::S3::Bucket" means S3 bucket = B [OK]

Hint: Look for "Type" value to identify resource created [OK]

Common Mistakes:

• Confusing S3 bucket with EC2 or Lambda
• Ignoring the resource type string
• Assuming resource names define type

4. You wrote this YAML snippet for a CloudFormation template but it fails to deploy:

Resources:
  MyInstance:
    Type: AWS::EC2::Instance
    Properties:
      ImageId: ami-12345678
      InstanceType: t2.micro
      SecurityGroups: my-security-group

What is the likely error?

medium

A. InstanceType is invalid for EC2

B. ImageId must be a number, not a string

C. SecurityGroups should be a list, not a single string

D. Resources section name is misspelled

Solution

1. Step 1: Check the SecurityGroups property format

   SecurityGroups expects a list of strings, but here it is a single string.

2. Step 2: Validate other properties

   ImageId is a string (correct), InstanceType is valid, Resources is spelled correctly.

3. Final Answer:

   SecurityGroups should be a list, not a single string -> Option C

4. Quick Check:

   SecurityGroups needs list format = A [OK]

Hint: Lists must be in brackets or dash format in YAML [OK]

Common Mistakes:

• Using string instead of list for SecurityGroups
• Assuming ImageId is numeric
• Misspelling Resources section

5. You want to create a reusable CloudFormation template that accepts a bucket name as input and outputs the bucket ARN. Which two sections must you include in your JSON template?

hard

A. Parameters and Outputs

B. Resources and Scripts

C. Functions and Parameters

D. Outputs and Commands

Solution

1. Step 1: Identify input and output sections needed

   To accept input like bucket name, use Parameters. To show output like ARN, use Outputs.

2. Step 2: Confirm other sections are invalid

   Scripts, Functions, Commands are not valid top-level sections in CloudFormation templates.

3. Final Answer:

   Parameters and Outputs -> Option A

4. Quick Check:

   Input = Parameters, Output = Outputs [OK]

Hint: Parameters take inputs; Outputs show results [OK]

Common Mistakes:

• Using non-existent sections like Scripts or Commands
• Confusing Resources with input/output sections
• Forgetting to include Outputs for results