Implementing Auto Scaling Groups (ASGs)

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Useful Links:
- Termination Policies
Exam Tips:
- Deployment Types - Image baking vs Bootstrapping:
  - A flexible deployment of EC2? AMI baking is not the way to go.
  - Need to deploy something at a certain speed?
    - If using bootstrapping, additional processing time is added.
    - Gain flexibility but lose speed.
- Autoscaling Groups:
  - Know the dividing line between launch configurations and ASG.
  - ASG:
    - Where and when to deploy instances.
    - MIN, MAX, Desired.
    - Has built-in health check.
  - Launch configuration (Legacy):
    - What to deploy:
      - Instance type.
      - AMI
      - Specify on-demand or spot.
      - Can enable detailed monitoring.
      - Security groups.
      - Key pairs.
    - Immutable, can create but not edit!
    - Any changes require a new launch configuration and then change the association in the ASG.
  - Launch templates:
    - Very similar to launch configuration.
    - Allow template versioning.
- Multi-AZ Implementations:
  - Be sure to plan placement based on requirements.
  - Understand nominal instances required.
  - May not be able to accept lost availability zones.
  - Make sure you can cope with a failure by using the least amount of buffer infrastructure.