Day 14 - EC2 Auto Scaling

Date: 2025-09-25 (Thursday)
Status: “Done”

Lecture Notes

Amazon EC2 Auto Scaling

  • EC2 Auto Scaling automatically adjusts the number of EC2 instances based on demand.

Benefits

  • Elastic capacity adjustment
  • Increased application availability
  • Cost optimization

Components

  • Auto Scaling Group (ASG) – logical group of EC2 instances
  • Launch Template / Configuration – defines instance parameters
  • Scaling Policies – rules for adding/removing instances

Scaling Policies

  • Simple / Step Scaling – add/remove instances when thresholds are met
  • Target Tracking – maintain a metric (e.g., CPU = 50%)
  • Scheduled Scaling – scale on a predefined schedule
  • Predictive Scaling – uses ML to forecast and scale proactively

Scaling Policy Examples:

{
  "TargetTrackingScalingPolicyConfiguration": {
    "PredefinedMetricSpecification": {
      "PredefinedMetricType": "ASGAverageCPUUtilization"
    },
    "TargetValue": 50.0
  }
}

Integration with Load Balancer

  • ASGs often pair with Elastic Load Balancers (ELB).
  • New instances automatically register; terminated instances deregister automatically.

Auto Scaling Best Practices:

  • Use multiple AZs for high availability
  • Set appropriate cooldown periods
  • Monitor CloudWatch metrics
  • Use lifecycle hooks for custom actions
  • Test scaling policies before production

EC2 Pricing Options

  • On-Demand: Pay per hour/second. Most expensive but flexible.
  • Reserved Instances: 1- or 3-year commitment for discount; tied to specific instance type/family.
  • Savings Plans: 1- or 3-year commitment; flexible across instance families.
  • Spot Instances: Use spare capacity at up to 90% discount; can be terminated with 2-minute notice.

Combine multiple pricing models within an Auto Scaling Group for cost optimization.

Pricing Comparison:

Model Discount Flexibility Commitment
On-Demand 0% High None
Reserved 40-60% Low 1-3 years
Savings Plans 40-60% Medium 1-3 years
Spot 50-90% Low None

Hands-On Labs

Lab 09 – AWS Support Plans

  1. AWS Support Packages → 09-01
  2. Types of Support Requests → 09-02
  3. Change Support Package → 09-03
  4. Manage Support Requests → 09-04