Launch templates in AWS - Step-by-Step Execution

Process Flow - Launch templates

Create Launch Template

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Define Configurations

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Save Template Version

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Launch EC2 Instance Using Template

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Instance Runs with Template Settings

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Optionally Create New Template Version

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Repeat Launch with Updated Configurations

The flow shows creating a launch template, defining settings, saving it, launching instances from it, and optionally updating the template for future launches.

Execution Sample

AWS

aws ec2 create-launch-template --launch-template-name MyTemplate --version-description v1 --launch-template-data '{"ImageId":"ami-12345678","InstanceType":"t2.micro"}'
aws ec2 run-instances --launch-template LaunchTemplateName=MyTemplate,Version=1

This code creates a launch template with an AMI and instance type, then launches an EC2 instance using that template.

Process Table

Step	Action	Input/Condition	Result/Output
1	Create launch template	Name=MyTemplate, Version=v1, Data={ImageId=ami-12345678, InstanceType=t2.micro}	Launch template MyTemplate version 1 created
2	Launch instance	Use LaunchTemplateName=MyTemplate, Version=1	EC2 instance launched with AMI ami-12345678 and type t2.micro
3	Instance state	Instance initializing	Instance state: pending
4	Instance state	Instance booting	Instance state: running
5	Optional: create new version	Update InstanceType to t3.micro	Launch template MyTemplate version 2 created
6	Launch instance	Use LaunchTemplateName=MyTemplate, Version=2	EC2 instance launched with AMI ami-12345678 and type t3.micro
7	End	No more launches	Execution stops

💡 No more instances to launch, process ends

Status Tracker

Variable	Start	After Step 1	After Step 5	Final
LaunchTemplateName	None	MyTemplate	MyTemplate	MyTemplate
Version	None	1	2	2
ImageId	None	ami-12345678	ami-12345678	ami-12345678
InstanceType	None	t2.micro	t3.micro	t3.micro
InstanceState	None	None	running	running

Key Moments - 3 Insights

Why do we need to specify a version when launching an instance?

Each launch template version can have different settings. Specifying the version ensures the instance uses the correct configuration, as shown in execution_table steps 2 and 6.

Can we update a launch template directly without creating a new version?

No, launch templates are immutable. To change settings, you create a new version (step 5), preserving previous versions for reuse.

What happens if we launch an instance without specifying a version?

AWS uses the default version of the launch template. This is not shown in the table but is important to know to avoid unexpected configurations.

Visual Quiz - 3 Questions

Look at the execution_table, what is the InstanceType used at step 6?

A t2.micro

B t3.micro

C ami-12345678

D pending

💡 Hint

Check the 'Result/Output' column at step 6 for the instance type.

At which step is a new launch template version created?

A Step 3

B Step 2

C Step 5

D Step 7

💡 Hint

Look for 'Launch template MyTemplate version 2 created' in the Result/Output column.

If we did not specify a version when launching an instance, what would happen?

A AWS uses the default launch template version

B AWS creates a new launch template version automatically

C The instance launch would fail

D The instance uses the latest version always

💡 Hint

Refer to key_moments explanation about default version usage.

Concept Snapshot

Launch templates store EC2 instance settings as reusable versions.
Create a template with configurations like AMI and instance type.
Launch instances by specifying template name and version.
Update settings by creating new versions, preserving old ones.
Using versions ensures consistent and repeatable instance launches.

Full Transcript

Launch templates in AWS let you save EC2 instance settings in a reusable way. First, you create a launch template with a name and version, defining details like the AMI and instance type. Then, you launch EC2 instances by referring to the template name and version. The instance starts with the saved settings. If you want to change settings, you create a new version of the launch template. This way, you keep old versions intact and can launch instances with different configurations as needed. Always specify the version when launching to control which settings are used. If you don't specify, AWS uses the default version. This process helps manage EC2 launches easily and consistently.