Auto-Scaling

There are three types of auto scaling services:

1. AWS Auto Scaling Service: Holistic scaling view + predictive scaling feature

2. EC2 Auto Scaling Service: Focused specifically on EC2 instance scaling

3. Application Auto Scaling Service: API for scaling non-EC2 AWS services

AWS Auto Scaling Service

• Provides holistic view of all auto scaling activities

• Manages scaling across different application layers

• Accessed through dedicated console

• Offers business-oriented scaling strategies

Application Auto Scaling

API-based service for non-EC2 resources. Manages scaling for services like:

• DynamoDB

• ECS

• EMR

Application Auto Scaling Consolidates various service-specific scaling capabilities into a single API.

There are three Application Auto Scaling types:

Scaling	What	When
Target Tracking Policy	Initiates scaling events to try to track as closely as possible a given target metric.	"I want my ECS hosts to stay at or below 70% CPU utilization."
Step Scaling Policy	Based on a metric, adjusts capacity given certain defined thresholds.	"I want to increase my EC2 Spot Fleet by 20% every time I add another 10,000 connections on my ELB"
Scheduled Scaling Policy	Initiates scaling events based on a predefined time, day or date.	"Every Monday at 0800, I want to increase the Read Capacity Units of my DynamoDB Table to 20,000"

EC2 Auto Scaling Service

Core Components

1. EC2 Auto Scaling Service

   • Primary service for EC2 resource scaling

   • Manages core scaling functionality

   • Handles policies, metrics, configurations

2. EC2 Auto Scaling Groups (ASG)

   • Logical grouping of EC2 instances

   • Implements scaling mechanisms

   • Manages instance monitoring

   • Controls min/max instances

   • Applies policies and health checks

ASG Scaling Types

1. Dynamic Scaling

Responds to real-time demand through three policy types:

Scaling Policies	What	When
Target Tracking Scaling Policy	Scale based on a predefined or custom metric in relation to a target value	"When CPU utilization gets to 70% on current instances, scale up."
Simple Scaling Policy	Waits until health check and cool down period expires before evaluating new need	"Let's add new instances slow and steady."
Step Scaling Policy	Responds to scaling needs with more sophistication and logic	"AGG! Add ALL the instances!"

2. Predictive Scaling

• Leverages machine learning algorithms

• Analyzes historical data to forecast scaling needs

• Offers automatic scaling and advisory insights

• Optional data collection feature

3. Scheduled Scaling

• Time-based pattern scaling

• Useful for known traffic patterns

ASG Operating Modes

1. Maintain Mode

   • Keeps a fixed instance count

   • No scaling types involved

   • Simply maintains desired capacity

2. Manual Mode

   • User-controlled scaling

   • No automatic scaling types

   • Changes made through manual intervention

3. Schedule-based Mode

   • Uses Scheduled Scaling

   • Time-based pattern scaling

   • Useful for known traffic patterns

4. Dynamic Mode

   • Uses both Dynamic and Predictive Scaling

   • Dynamic Scaling Options:

     • Target Tracking Policy

     • Simple Scaling Policy

     • Step Scaling Policy

   • Predictive Scaling Features:

     • ML-based forecasting

     • Historical data analysis

     • Optional data collection

Configuration Elements

Launch Configuration

• AMI specifications

• VPC settings

• Load balancer integration

• Network configurations

Health Check Grace Period

• Allows time for instance initialization

• Prevents premature health check failures

Cooldown Periods

• Default: 300 seconds

• Purpose: Stabilization time between scaling events

• Applies to:

  • Dynamic scaling (mandatory)

  • Manual scaling (optional)

  • Scheduled scaling (not supported)

• Can be customized for specific scenarios

Scaling Based on Amazon SQS