AWS Launch Templates and Step-by-Step Guide for Creating Auto Scaling Groups ||aws course

A launch template shares similarities with a launch configuration, as it specifies instance configuration details such as the Amazon Machine Image (AMI) ID, instance type, key pair, security groups, and other parameters necessary for launching EC2 instances. However, opting for a launch template over a launch configuration provides the benefit of supporting multiple versions of the launch template.

With the introduction of versioning for launch templates, you can create a subset of the full parameter set and then reuse it to generate other iterations of the same launch template. For instance, you could establish a launch template defining a foundational configuration that lacks an AMI or user data script. Subsequently, after creating the initial launch template, you can produce a new version, incorporating the latest AMI and user data relevant to your application for testing purposes. This results in having two versions of the launch template. By preserving this foundational configuration, you ensure that essential general configuration parameters are maintained. Whenever necessary, you can initiate a new version of your launch template based on the foundational configuration. Additionally, you have the flexibility to remove versions used for testing your application once they are no longer required.

An Auto Scaling group is a container that houses a group of EC2 instances, treating them as a cohesive entity for the purpose of facilitating automatic scaling and management. This group also grants access to Amazon EC2 Auto Scaling features such as health check replacements and scaling policies. Both the tasks of sustaining the instance count within an Auto Scaling group and executing automatic scaling operations represent the fundamental functions of the Amazon EC2 Auto Scaling service.

The scale of an Auto Scaling group is contingent upon the quantity of instances designated as the desired capacity. You have the flexibility to modify the group's size to accommodate changes in demand, either through manual adjustments or by utilizing automatic scaling mechanisms.

Initially, an Auto Scaling group initiates by launching a sufficient number of instances to meet its desired capacity. It sustains this specific instance count by conducting periodic health assessments on all the instances within the group. The Auto Scaling group persists in maintaining a constant number of instances, even if an instance's health deteriorates. In case an instance is identified as unhealthy, the group takes the action of terminating the problematic instance and simultaneously launches a new one to replace it.

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