14 - Launch Configurations Vs Launch Templates

Question 1

What is a launch configuration?

Answer 1

• A launch configuration is a template that an EC2 Auto Scaling group uses to launch EC2 instances.
• Specify information for the instances such as the
  
  • ID of the Amazon Machine Image (AMI)
  • instance type
  • key pair
  • one or more security groups
  • block device mapping.
• Create an EC2 Auto Scaling group, you must specify a launch configuration.
  
  • You can specify your launch configuration with multiple EC2 Auto Scaling groups.
  • However, you can only specify one launch configuration for an EC2 Auto Scaling group at a time
  • you can’t modify a launch configuration after you’ve created it.
• Changing a Launch Configuration
  
  • Must create a launch configuration and then update your EC2 Auto Scaling group with the new launch configuration.
  • When you change the launch configuration for your EC2 Auto Scaling group, any new instances are launched using the new configuration parameters, but existing instances are not affected.

Question 2

What is a Launch Template?

Answer 2

• Similar to a launch configuration, in that it specifies instance configuration information.
• Defining a launch template instead of a launch configuration allows you to have multiple versions of a launch template.
• It includes the
  
  • ID of the Amazon Machine Image (AMI)
  • instance type
  • key pair
  • security groups
  • other parameters
• Versioning
  
  • With versioning of launch templates, you can create a subset of the full set of parameters.
  • Then, you can reuse it to create other versions of the same launch template.
• Launch templates are recommended over Launch Configurations
  
  • Not all Amazon EC2 Auto Scaling features are available when you use launch configurations.
  • For example, you cannot create an Auto Scaling group that launches both Spot and On-Demand Instances or that specifies multiple instance types.
  • With launch templates, you can also use newer features of Amazon EC2.