Elastic Load Balancing automatically distributes incoming application traffic across multiple Amazon EC2 instances. It enables you to achieve fault tolerance in your applications by seamlessly providing the required amount of load balancing capacity needed to route application traffic.
Auto Scaling helps you maintain application availability and allows you to scale your Amazon EC2 capacity out or in automatically according to conditions you define. You can use Auto Scaling to help ensure that you are running your desired number of Amazon EC2 instances. Auto Scaling can also automatically increase the number of Amazon EC2 instances during demand spikes to maintain performance and decrease capacity during lulls to reduce costs. Auto Scaling is well suited to applications that have stable demand patterns or that experience hourly, daily, or weekly variability in usage.
Create an Amazon Machine Image (AMI) from a running instance. Create a load balancer. Create a launch template and an Auto Scaling group. Automatically scale new instances Create Amazon CloudWatch alarms and monitor the performance of your infrastructure.
In this task, you will create an AMI from the existing Web Server 1. This will save the contents of the boot disk so that new instances can be launched with identical content.
In the AWS Management Console, in the search box next to Services , search for and select EC2.
In the left navigation pane, choose Instances.
First, you will confirm that the instance is running.
Wait until the Status Checks for Web Server 1 displays 2/2 checks passed. If necessary, choose refresh to update the status.
You will now create an AMI based upon this instance.
Select Web Server 1.
In the Actions menu, choose Image and templates > Create image, then configure:
Image name: WebServerAMI Image description: Lab AMI for Web Server Choose Create image
A confirmation banner displays the AMI ID for your new AMI.
You will use this AMI when launching the Auto Scaling group later.
In this task, you will create a load balancer that can balance traffic across multiple EC2 instances and Availability Zones.
In the left navigation pane, choose Target Groups.
Analysis: Target Groups define where to send traffic that comes into the Load Balancer. The Application Load Balancer can send traffic to multiple Target Groups based upon the URL of the incoming request, such as having requests from mobile apps going to a different set of servers. Your web application will use only one Target Group.
Choose Create target group Choose a target type: Instances Target group name, enter: LabGroup Select Lab VPC from the VPC drop-down menu. Choose Next. The Register targets screen appears.
Note: Targets are the individual instances that will respond to requests from the Load Balancer.
You do not have any web application instances yet, so you can skip this step.
Review the settings and choose Create target group
In the left navigation pane, choose Load Balancers.
At the top of the screen, choose Create load balancer.
Several different types of load balancer are displayed. You will be using an Application Load Balancer that operates at the request level (layer 7), routing traffic to targets — EC2 instances, containers, IP addresses and Lambda functions — based on the content of the request. For more information, see: Comparison of Load Balancers
Under Application Load Balancer, choose Create
Under Load balancer name, enter: LabELB
Scroll down to the Network mapping section, then:
For VPC, choose Lab VPC
You will now specify which subnets the Load Balancer should use. The load balancer will be internet facing, so you will select both Public Subnets.
Choose the first displayed Availability Zone, then select Public Subnet 1 from the Subnet drop down menu that displays beneath it.
Choose the second displayed Availability Zone, then select Public Subnet 2 from the Subnet drop down menu that displays beneath it.
You should now have two subnets selected: Public Subnet 1 and Public Subnet 2.
In the Security groups section:
Choose the Security groups drop down menu and select Web Security Group
Below the drop down menu, choose the X next to the default security group to remove it.
The Web Security Group security group should now be the only one that appears.
For the Listener HTTP:80 row, set the Default action to forward to LabGroup.
Scroll to the bottom and choose Create load balancer
The load balancer is successfully created.
Choose View load balancer
The load balancer will show a state of provisioning. There is no need to wait until it is ready. Please continue with the next task.
In this task, you will create a launch template for your Auto Scaling group. A launch template is a template that an Auto Scaling group uses to launch EC2 instances. When you create a launch template, you specify information for the instances such as the AMI, the instance type, a key pair, and security group.
In the left navigation pane, choose Launch Templates.
Choose Create launch template
Configure the launch template settings and create it:
Launch template name: LabConfig
Under Auto Scaling guidance, select Provide guidance to help me set up a template that I can use with EC2 Auto Scaling
In the Application and OS Images (Amazon Machine Image) area, choose My AMIs.
Amazon Machine Image (AMI): choose Web Server AMI
Instance type: choose t2.micro
Key pair name: choose vockey
Firewall (security groups): choose Select existing security group
Security groups: choose Web Security Group
Scroll down to the Advanced details area and expand it.
Scroll down to the Detailed CloudWatch monitoring setting. Select Enable
Note: This will allow Auto Scaling to react quickly to changing utilization.
Choose Create launch template
Next, you will create an Auto Scaling group that uses this launch template.
In the Success dialog, choose the LabConfig launch template.
From the Actions menu, choose Create Auto Scaling group.
Note: Make sure the region is set to N. Virginia.
Configure the details in Step 1 (Choose launch template or configuration):
Auto Scaling group name: Lab Auto Scaling Group
Launch template: confirm that the LabConfig template you just created is selected.
Choose Next
Configure the details in Step 2 (Choose instance launch options):
VPC: choose Lab VPC
Availability Zones and subnets: Choose Private Subnet 1 and then choose Private Subnet 2.
Choose Next
Configure the details in Step 3 (Configure advanced options):
Choose Attach to an existing load balancer
Existing load balancer target groups: select LabGroup. In the Additional settings pane:
Select Enable group metrics collection within CloudWatch This will capture metrics at 1-minute intervals, which allows Auto Scaling to react quickly to changing usage patterns.
Choose Next
Configure the details in Step 4 (Configure group size and scaling policies - optional):
Under Group size, configure:
Desired capacity: 2
Minimum capacity: 2
Maximum capacity: 6
This will allow Auto Scaling to automatically add/remove instances, always keeping between 2 and 6 instances running.
Under Scaling policies, choose Target tracking scaling policy and configure:
Scaling policy name: LabScalingPolicy
Metric type: Average CPU Utilization
Target value: 60
This tells Auto Scaling to maintain an average CPU utilization across all instances at 60%. Auto Scaling will automatically add or remove capacity as required to keep the metric at, or close to, the specified target value. It adjusts to fluctuations in the metric due to a fluctuating load pattern.
Choose Next
Configure the details in Step 5 (Add notifications - optional):
Auto Scaling can send a notification when a scaling event takes place. You will use the default settings.
Choose Next Configure the details in Step 6 (Add tags - optional):
Tags applied to the Auto Scaling group will be automatically propagated to the instances that are launched.
Choose Add tag and Configure the following:
Key: Name Value: Lab Instance Choose Next
Configure the details in Step 6 (Review):
Review the details of your Auto Scaling group
Choose Create Auto Scaling group
Your Auto Scaling group will initially show an instance count of zero, but new instances will be launched to reach the Desired count of 2 instances.
In this task, you will verify that Load Balancing is working correctly.
In the left navigation pane, choose Instances.
You should see two new instances named Lab Instance. These were launched by Auto Scaling.
If the instances or names are not displayed, wait 30 seconds and choose refresh in the top-right.
Next, you will confirm that the new instances have passed their Health Check.
In the left navigation pane, choose Target Groups.
Select LabGroup
Choose the Targets tab.
Two target instances named Lab Instance should be listed in the target group.
Wait until the Status of both instances transitions to healthy.
Choose Refresh in the upper-right to check for updates if necessary.
Healthy indicates that an instance has passed the Load Balancer's health check. This means that the Load Balancer will send traffic to the instance.
You can now access the Auto Scaling group via the Load Balancer.
In the left navigation pane, choose Load Balancers.
Select the LabELB load balancer.
In the Details pane, copy the DNS name of the load balancer, making sure to omit "(A Record)".
It should look similar to: LabELB-1998580470.us-west-2.elb.amazonaws.com
Open a new web browser tab, paste the DNS Name you just copied, and press Enter.
The application should appear in your browser. This indicates that the Load Balancer received the request, sent it to one of the EC2 instances, then passed back the result.
You created an Auto Scaling group with a minimum of two instances and a maximum of six instances. Currently two instances are running because the minimum size is two and the group is currently not under any load. You will now increase the load to cause Auto Scaling to add additional instances.
Return to the AWS Management Console, but do not close the application tab — you will return to it soon.
in the search box next to Services , search for and select CloudWatch.
In the left navigation pane, choose All alarms.
Two alarms will be displayed. These were created automatically by the Auto Scaling group. They will automatically keep the average CPU load close to 60% while also staying within the limitation of having two to six instances.
Note: Please follow these steps only if you do not see the alarms in 60 seconds.
On the Services menu, choose EC2. In the left navigation pane, choose Auto Scaling Groups. Select Lab Auto Scaling Group. In the bottom half of the page, choose the Automatic Scaling tab. Select LabScalingPolicy. Choose Actions and Edit. Change the Target Value to 50. Choose Update On the Services menu, choose CloudWatch. In the left navigation pane, choose All alarms and verify you see two alarms.
Choose the OK alarm, which has AlarmHigh in its name.
If no alarm is showing OK, wait a minute then choose refresh in the top-right until the alarm status changes.
The OK indicates that the alarm has not been triggered. It is the alarm for CPU Utilization > 60, which will add instances when average CPU is high. The chart should show very low levels of CPU at the moment.
You will now tell the application to perform calculations that should raise the CPU level.
Return to the browser tab with the web application.
Choose Load Test beside the AWS logo.
This will cause the application to generate high loads. The browser page will automatically refresh so that all instances in the Auto Scaling group will generate load. Do not close this tab.
Return to browser tab with the CloudWatch console.
In less than 5 minutes, the AlarmLow alarm should change to OK and the AlarmHigh alarm status should change to In alarm.
You can choose Refresh in the top-right every 60 seconds to update the display.
You should see the AlarmHigh chart indicating an increasing CPU percentage. Once it crosses the 60% line for more than 3 minutes, it will trigger Auto Scaling to add additional instances.
Wait until the AlarmHigh alarm enters the In alarm state.
You can now view the additional instance(s) that were launched.
In the search box next to Services , search for and select EC2.
In the left navigation pane, choose Instances.
More than two instances labeled Lab Instance should now be running. The new instance(s) were created by Auto Scaling in response to the CloudWatch alarm.
In this task, you will terminate Web Server 1. This instance was used to create the AMI used by your Auto Scaling group, but it is no longer needed.
Select Web Server 1 (and ensure it is the only instance selected).
In the Instance state menu, choose Instance State > Terminate Instance.
Choose Terminate