Launch templates in AWS - Mini Project: Build & Apply

Create and Configure an AWS Launch Template

📖 Scenario: You are setting up a cloud environment where you want to launch virtual machines (EC2 instances) with consistent settings. To do this efficiently, you will create an AWS Launch Template that stores the configuration for these instances.

🎯 Goal: Build an AWS Launch Template that defines the instance type, Amazon Machine Image (AMI), and key pair for secure access. This template will help you launch EC2 instances with the same settings easily.

📋 What You'll Learn

Create a launch template named MyLaunchTemplate

Set the AMI ID to ami-0abcdef1234567890

Set the instance type to t3.micro

Specify the key pair name as MyKeyPair

💡 Why This Matters

🌍 Real World

Launch templates help cloud engineers quickly and consistently launch virtual machines with predefined settings, saving time and reducing errors.

💼 Career

Understanding launch templates is essential for roles like cloud engineer, DevOps engineer, and system administrator working with AWS infrastructure.

1

Create the basic launch template data structure

Create a dictionary called launch_template_data with keys ImageId set to "ami-0abcdef1234567890" and InstanceType set to "t3.micro".

AWS

# Your code here

Hint

Think of launch_template_data as a box holding your instance settings like the image and size.

2

Add the key pair configuration

Add a key KeyName with value "MyKeyPair" to the existing launch_template_data dictionary.

AWS

launch_template_data = {
    "ImageId": "ami-0abcdef1234567890",
    "InstanceType": "t3.micro"
}
# Add the key pair name below

Hint

The key pair lets you securely connect to your instance. Add it as another setting in the dictionary.

3

Create the launch template request dictionary

Create a dictionary called launch_template_request with keys LaunchTemplateName set to "MyLaunchTemplate" and LaunchTemplateData set to the launch_template_data dictionary.

AWS

launch_template_data = {
    "ImageId": "ami-0abcdef1234567890",
    "InstanceType": "t3.micro",
    "KeyName": "MyKeyPair"
}
# Create launch_template_request dictionary below

Hint

This dictionary groups the template name and its data together, ready to be sent to AWS.

4

Add the version description to the launch template data

Add a key VersionDescription with value "Initial version" to the launch_template_data dictionary inside launch_template_request.

AWS

launch_template_data = {
    "ImageId": "ami-0abcdef1234567890",
    "InstanceType": "t3.micro",
    "KeyName": "MyKeyPair"
}

launch_template_request = {
    "LaunchTemplateName": "MyLaunchTemplate",
    "LaunchTemplateData": launch_template_data
}
# Add VersionDescription to launch_template_data below

Hint

The version description helps you track changes to your launch template over time.

Practice

1. What is the main purpose of an AWS Launch Template?

easy

A. To automatically back up EC2 instance data

B. To monitor running EC2 instances in real-time

C. To store configuration settings for launching EC2 instances consistently

D. To manage user permissions for EC2 instances

Solution

1. Step 1: Understand Launch Template role

   Launch templates save settings like instance type, AMI, and security groups for EC2 instances.

2. Step 2: Identify main purpose

   This helps launch instances with consistent configurations quickly and easily.

3. Final Answer:

   To store configuration settings for launching EC2 instances consistently -> Option C

4. Quick Check:

   Launch Template = Configuration storage [OK]

Hint: Launch templates save instance settings for reuse [OK]

Common Mistakes:

• Confusing launch templates with monitoring tools
• Thinking launch templates handle backups
• Assuming launch templates manage permissions

2. Which of the following is the correct way to specify a launch template version in an AWS CLI command to run an EC2 instance?

easy

A. aws ec2 run-instances --launch-template LaunchTemplateId=lt-12345678,Version=2

B. aws ec2 run-instances --template-id lt-12345678 --version 2

C. aws ec2 run-instances --launch-template-id lt-12345678 --template-version 2

D. aws ec2 run-instances --launch-template lt-12345678 version=2

Solution

1. Step 1: Recall AWS CLI syntax for launch templates

   The correct syntax uses --launch-template with parameters LaunchTemplateId and Version separated by commas.

2. Step 2: Match syntax to options

   aws ec2 run-instances --launch-template LaunchTemplateId=lt-12345678,Version=2 matches the correct syntax exactly.

3. Final Answer:

   aws ec2 run-instances --launch-template LaunchTemplateId=lt-12345678,Version=2 -> Option A

4. Quick Check:

   Correct CLI syntax = aws ec2 run-instances --launch-template LaunchTemplateId=lt-12345678,Version=2 [OK]

Hint: Use --launch-template LaunchTemplateId=ID,Version=NUM [OK]

Common Mistakes:

• Using incorrect parameter names like --template-id
• Separating parameters with spaces instead of commas
• Omitting the 'Version=' keyword

3. Given this launch template version history:
Version 1: AMI ami-11111111, InstanceType t2.micro
Version 2: AMI ami-22222222, InstanceType t2.small
If you launch an instance specifying version 1, what will be the instance type?

medium

A. t2.small

B. t2.micro

C. t2.medium

D. The latest version's instance type

Solution

1. Step 1: Identify version specified in launch

   The question says version 1 is specified for launching the instance.

2. Step 2: Check instance type in version 1

   Version 1 has instance type t2.micro, so that will be used.

3. Final Answer:

   t2.micro -> Option B

4. Quick Check:

   Specified version settings apply = t2.micro [OK]

Hint: Specified version settings override latest [OK]

Common Mistakes:

• Assuming latest version is always used
• Confusing AMI with instance type
• Ignoring version number in launch command

4. You tried to launch an EC2 instance using a launch template but got an error: "Invalid launch template version specified." What is the most likely cause?

medium

A. The launch template ID is incorrect

B. The instance type is not supported in the region

C. The AMI in the launch template is deprecated

D. The specified version number does not exist in the launch template

Solution

1. Step 1: Analyze error message

   The error says "Invalid launch template version specified," indicating a problem with the version number.

2. Step 2: Identify cause

   This usually means the version number given does not exist or is mistyped.

3. Final Answer:

   The specified version number does not exist in the launch template -> Option D

4. Quick Check:

   Error about version = wrong version number [OK]

Hint: Check version number exists in template [OK]

Common Mistakes:

• Assuming AMI or instance type causes version error
• Not verifying launch template ID correctness
• Ignoring error details about version

5. You want to update a launch template to change the instance type but keep the original version intact for rollback. What is the best practice to achieve this?

hard

A. Create a new version of the existing launch template with the updated instance type

B. Modify the existing launch template version directly

C. Create a new launch template with the updated instance type

D. Delete the old launch template and create a new one with the updated instance type

Solution

1. Step 1: Understand launch template versioning

   Launch templates support multiple versions to track changes safely without overwriting.

2. Step 2: Choose update method preserving old version

   Creating a new version keeps the old version intact for rollback if needed.

3. Final Answer:

   Create a new version of the existing launch template with the updated instance type -> Option A

4. Quick Check:

   Use versioning to update safely = Create a new version of the existing launch template with the updated instance type [OK]

Hint: Use new version to update, keep old for rollback [OK]

Common Mistakes:

• Modifying existing version directly (not allowed)
• Deleting old template loses rollback option
• Creating new template duplicates effort unnecessarily