Autoscaling Setup

1. Introduction

Goal of This Tutorial: The goal of this tutorial is to guide you on how to set up autoscaling for a server farm. By the end of this tutorial, you will have a server farm that can automatically adjust the number of active servers based on load.

Learning Outcome: You will learn the concept of autoscaling, how to set up an autoscaling group, and how to specify scaling policies.

Prerequisites:
- Basic understanding of server infrastructure
- Familiarity with AWS (Amazon Web Services) as the tutorial uses AWS EC2 (Elastic Compute Cloud) for examples

2. Step-by-Step Guide

Autoscaling ensures that you have the correct number of servers available to handle the load for your application. You set conditions for scaling up (adding more servers) and down (removing servers), and the service handles the rest.

Setting Up An Autoscaling Group

1. Create a Launch Configuration: Before setting up an autoscaling group, you need to create a launch configuration. This specifies the instance type, AMI (Amazon Machine Image), and security groups for your instances.

2. Create an Autoscaling Group: Once you have a launch configuration, you can set up an autoscaling group. This group uses the launch configuration to launch instances. You can specify the minimum, maximum, and desired number of instances in this group.

3. Specify Scaling Policies: Scaling policies determine when to scale up or down. You can set a target value for a specific CloudWatch metric (like CPU utilization), and AWS will add or remove instances to maintain this target.

3. Code Examples

Using AWS CLI (Command Line Interface), you can create and manage your autoscaling setup.

Create Launch Configuration

# Create a launch configuration
aws autoscaling create-launch-configuration --launch-configuration-name my-lc --image-id ami-abc12345 --instance-type t2.micro

This command creates a launch configuration named "my-lc", using the AMI with the ID "ami-abc12345" and the instance type "t2.micro".

Create Autoscaling Group

# Create an autoscaling group
aws autoscaling create-auto-scaling-group --auto-scaling-group-name my-asg --launch-configuration-name my-lc --min-size 1 --max-size 5 --desired-capacity 3

This command creates an autoscaling group named "my-asg", using the launch configuration "my-lc". It sets a minimum size of 1 instance, a maximum size of 5 instances, and a desired capacity of 3 instances.

Specify Scaling Policies

# Create a scaling policy
aws autoscaling put-scaling-policy --policy-name my-scaleout-policy --auto-scaling-group-name my-asg --scaling-adjustment 1 --adjustment-type ChangeInCapacity

This command creates a scaling policy named "my-scaleout-policy", which adds 1 instance to the autoscaling group "my-asg" whenever the policy is executed.

4. Summary

In this tutorial, you learned about autoscaling, how to set up an autoscaling group, and how to specify scaling policies. You can now set up an infrastructure that can automatically adjust the number of active servers based on load.

For more advanced topics, consider learning about lifecycle hooks, scheduled scaling, and predictive scaling.

5. Practice Exercises

1. Exercise: Create an autoscaling group with a minimum size of 2 instances, a maximum size of 6 instances, and a desired capacity of 4 instances.

2. Exercise: Create a scaling policy that removes 2 instances from your autoscaling group.

Remember to test your setup by simulating high load situations and checking if the autoscaling responds correctly.

Happy scaling!