Auto Scaling in AWS

Dear Readers,

In this article, we will see the Auto Scaling in AWS.

For creating Auto Scaling we need to follow below steps.

1. Create Load Balancer
2. Launch Configurations
3. Create Auto Scaling Groups

First, we need to AWS Console page by using below link

https://aws.amazon.com/console/

Click on sign in to Console button.

Logging to aws account

Provide username and password then click on sign in.

Enter to AWS Management Console

We can see the AWS Management Console Dashboard.

Go to Services, under the compute module click on EC2 service to open.

STEP 1

Create Load Balancer

Now, in the left navigation scroll down and click on Load Balancers. 

Click on Create Load Balancer  button at the top.

Choose the Classic Load Balancer.

Go to Classic Load Balancer and click on create.

Define Load Balancer Basic Configuration

Give a name to your load balancer “MyLBCG” and select at least two availability zones for high availability and click on the Configure Security Settings button.

Assign Security Groups

Here select the new security group option and select the news security group that you provide security group name and description and click on Add Rule.

Add SSH port then click on Configure Security Settings.

Configure Security Settings

You may see a warning message just ignore that and click on Configure Health Check.

Configure Health Check

On the Configure Health Check page, leave Ping Protocol set to HTTP and Ping Port set to 80.

For Ping Path, replace the default value with a single forward slash (“/”). This tells Elastic Load Balancing to send health check queries to the default home page for your web server, such as index.html.

For Advanced Details, change the values if required

Choose Add EC2 Instances.

Add EC2 Instances

Click on Add Tags.

Add Tags

You can tag your load balancer, or continue to the next step then click on Review and Create.

Review

Verify all the details and click on create.

The load balancer has been successfully created then click on close.

We can see the load balancer, select the load balancer then it will show all the details regarding to the load balancer.

 

STEP 2

Launch Configurations

Now, in the left navigation scroll down and click on Auto Scaling. Click on the Launch Configuration button at the top.

Click on Create Launch Configuration.

Choose an Amazon Machine Image (AMI)

Select the Operating system of the EC2 instance by choosing any of the Amazon Machine Images (AMI). Select the Amazon Linux 2 AMI.

Choose an Instance type

Choose the Type of instance depending on your requirements.

Instance types comprise of varying combinations of CPU, memory, storage, and networking capacity so you can choose the appropriate mix for your applications.

select the default option of t2. micro – this instance type is covered within the free tier. Then click on Configure Instance Details.

Configure Details

Provide name and click on Advanced Details.

Go to Advanced Details and add required commands in user data

The commands are

#!/bin/bash

sudo su

yum update -y

yum install httpd -y

cd /var/www/html

echo “ktexperts will help us to get knowledge” > index.html

service httpd start

chkconfig httpd on

click on Add Storage.

Add Storage

Here, we can see root volume by default and size of 8GB

Add a new volume if required and click on Configure Security Groups.

Select existing security group “WebSSG” and click on Review.

Verify all the details and click on Create Launch Configuration.

To connect to your virtual machine, you need a key pair. A key pair is used to log into your instance and select create a new key pair

Create a new key pair and name it MyAutoScale. Then click Download Key Pair.

After you have downloaded and saved your key pair, click Create Launch Instance to start your Linux Server instance.

Click on Create Launch Configuration.

MyAutoScale.pem will be downloaded to your computer — make sure to save this key pair in a safe location on your computer.

STEP 3

Create Auto Scaling Groups

Click on Auto Scaling group using this launch configuration.

Configure Auto Scaling Group Details

Provide Group Name, Group Size (how many instances are up and running always) and choose the subnet(Availability Zones).

Select 3 availability zones  one by one in sub net.

Go to Advanced Details and Enter required details.

Click on check box receiving traffic from one or more load balancers

Provide classic load balancer name, health check type, health check grace period and click on Configure Scaling Polices.

Configure Scaling Group

Click on use scaling policies to adjust capacity of this group and you can specify the minimum “4” and maximum number “10” of instance in this group.

Click on scale the auto scaling group using step or simple scaling policies.

It works based on alarm, so first create the alarm by clicking on ‘add new alarm’.

Increase Group Size

Here the alarm created is based on CPU utilization above 90%. If CPU utilization crosses 90% 1 consecutive period of 5 minutes then the auto scaling launches 1 new instance based on the step action then click on Create Alarm.

In the Take the action choose Add option and select instances number (I have selected 1 instance) and mention time for instance need (300sec).

Decrease Group Size

It works based on alarm, so first create the alarm by clicking on ‘add new alarm’.

Here the alarm created is based on CPU utilization below 30%. If CPU utilization below 30% 1 consecutive period of 5 minutes then the auto scaling terminates 1 new instance based on the step action then click on Create Alarm..

In the Take the action choose Remove option and select instances number (I have selected 1 instance) then click on Configure Notifications.

Configure Notifications

Skip the notifications and click on Configure Tags.

Configure Tags

Provide key “Name” and Value “WebServer” for webservers and click on Review.

Review

Verify all the details and click on Create Auto Scaling Group.

The Auto Scaling group has been created successfully and click on close.

We can see the Auto Scaling Group “MyASG”

Go to Instances and check the webservers

Here 4 webservers are running and their status is initializing (it will take to some time to ready).

Go to Load Balancers then check status of all the webservers in the instances tab, the 4 webservers are in InService (Active State).

Go to Description copy DNS name.

Search DNS name in browser URL.

Testing

Terminate 3 webservers

Go to Instances and select 3 webservers.

Go to Actions, click on Terminate in instance state.

Click on Yes, Terminate.

The selected 3 webservers are going to shutting down.

Now, only one is server is up and running.

Refresh the DNS name which was searched recently in browser URL.

The 3 webservers are terminated successfully

The auto scaling wait for 300 sec then it will create the one webserver

We can see one webserver is initializing (at the back end all the packages are running).

After successfully creation of one webserver the auto scaling take break again 300 sec then create one more webserver.

After successfully creation of one webserver the auto scaling take break again 300 sec then create one more webserver.

Now the 4 webservers are in up and running.

Stop 3 webservers

We need to select required webservers to stop ( I have selected 3 webservers).

Go to Actions then click on stop in instance state.

Click on Yes, Stop.

Now, The selected web servers are being stopped.

We can see the selected web servers has been stopped successfully

In the Singapore region will have 3 availability zones (ap-southeast-1a, ap-southeast-1b, ap-southeast-1c)

Here Only one webserver is running in ap-southeast-1a availability zone

The terminated webservers are in 3 availability zones are

• ap-southeast-1a
• ap-southeast-1b
• ap-southeast-1c

The stopped webservers are in 3 availability zones are

• ap-southeast-1b
• ap-southeast-1b
• ap-southeast-1c

After 300 sec the auto scaling came into the picture and terminate the stopped webserver automatically

Here we can see the stopped webserver is in ap-southeast-1c that to be terminated.

After 300 sec the auto scaling came into the picture and terminate the stopped webserver automatically

Here we can see the stopped webserver is in ap-southeast-1c that to be terminated.

Having completed 300 sec Auto Scaling will create one webserver

The running 2 webservers are in 2 availability zones are

• ap-southeast-1a
• ap-southeast-1c

The terminated 4 webservers are in 3 availability zones are

• ap-southeast-1a
• ap-southeast-1b
• ap-southeast-1c
• ap-southeast-1c

The stopped webservers are in 2 availability zones are

• ap-southeast-1b
• ap-southeast-1b

Here the auto scaling terminates the webserver which is in stopped state then take 300 sec breaks then create one webserver in the same availability zone

The running 3 webservers are in 3 availability zones are

• ap-southeast-1a
• ap-southeast-1c
• ap-southeast-1b

The terminated 5 webservers are in 3 availability zones are

• ap-southeast-1a
• ap-southeast-1b
• ap-southeast-1c
• ap-southeast-1c
• ap-southeast-1b

The stopped webservers are in one availability zone is

• ap-southeast-1b

Here The auto scaling terminates the webserver which is in stopped state under ap-southeast-1b availability zone then take 300 sec breaks then create one webserver in another availability zone is ap-southeast-1a

The running 4 webservers are in 3 availability zones are

• ap-southeast-1a
• ap-southeast-1c
• ap-southeast-1b
• ap-southeast-1a

The terminated  6 webservers are in 3 availability zones are

• ap-southeast-1a
• ap-southeast-1b
• ap-southeast-1c
• ap-southeast-1c
• ap-southeast-1b
• ap-southeast-1b

The 4 webservers running and remaining servers are in terminated state, auto scaling it self decides the availability zones we don’t have any control of that.

The running 4 webservers are in 3 availability zones are

• ap-southeast-1a
• ap-southeast-1c
• ap-southeast-1b
• ap-southeast-1a

After some time the terminated machines are not visible in instances list.

 

 

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