The purpose of this demo is show how to use some AWS services to create a scalable architecture. We are going to create a web app architecture and do a load test.

The architecture above shows a VPC separating the subnets in public and private subnets, a high scalable application layer utilizing AutoScaling and a high scalable data layer with managed cache service (Amazon ElastiCache) to store sessions and managed relational database service (Amazon RDS) with replicas to scale reads. Also, we are storing static assets in a bucket (Amazon S3) and utilizing a CDN (Amazon CloudFront) to deliver the static assets and minimize latency to deliver dynamic content.

To test the application architecture we are utilizing the tool Locust, an open source load testing tool, to simulate users acessing our workload.

To get started you will need an IAM user with the following access:

• CloudFormation
• EC2
• CloudFront
• ElastiCache
• RDS
• S3
• VPC
• CloudWatch
• Route53
• IAM

Notes:

• Tested in the N. Virginia region (us-east-1);
• CF is just creating two subnets (public, private-app), different from the architecture;
• RDS is not implemented yet to test Read Replicas.

1. Download the repository or copy the CloudFormation template template-app.yml at cf-templates folder;
2. Open the CloudFormation console at https://console.aws.amazon.com/cloudformation
3. On the Step 1 - Specify template: Choose Upload a template file, click on Choose file button and select the template-app.yml located inside deploy directory
4. On the Step 2 - Specify stack details: Enter the Stack name as 'scaling-web'
5. On the Step 3 - Configure stack options: Just click on Next button
6. On the Step 4 - Review: Enable the checkbox I acknowledge that AWS CloudFormation might create IAM resources with custom names., and click on Create Stack button
7. Wait for the stack get into status CREATE_COMPLETE
8. Under the Outputs tab, take a note of ELB value
9. Open in a new tab the app utilizing the ELB DNS

1. Download the repository or copy the CloudFormation template template-test.yml at cf-templates folder;
2. Open the CloudFormation console at https://console.aws.amazon.com/cloudformation
3. On the Step 1 - Specify template: Choose Upload a template file, click on Choose file button and select the template-test.yml located inside deploy directory
4. On the Step 2 - Specify stack details: Enter the Stack name as 'locust' and change the parameter TargetEndpoint utilizing the ELB value noted at the first stage. For example: https://www.yourwebsite.com
5. On the Step 3 - Configure stack options: Just click on Next button
6. On the Step 4 - Review: Enable the checkbox I acknowledge that AWS CloudFormation might create IAM resources with custom names., and click on Create Stack button
7. Wait for the stack get into status CREATE_COMPLETE
8. Under the Outputs tab, take a note of Locust master instance DNS
9. Open in a new tab the locust page utilizing the DNS noted

1. Now, you are going to do some load test to see the behavior of the application
2. On the Locust page, after the number of slaves is the total you asked for, start simulating 10000 users with a hacth rate of 50
3. Look at the CloudWatch metrics of Application Load Balancer and EC2 to see how it works
4. Repeat the test with different parameters to collect more metrics if necessary

1. Go to EC2 console at https://console.aws.amazon.com/ec2
2. Go to your AppInstance, Actions, Instance setting and copy the user data
3. Create a new Launch Template
4. Select Amazon Linux 2 64-bit (x86) at Amazon machine image (AMI) field
5. On Instance type select t3.micro
6. At the networking stage select VPC and WebSg
7. Add new tag Name with value of webapp
8. Go to Advanced Details and paste the user data
9. Click on Create

1. Go to AutoScaling group and click on create
2. Select Launch Template and filter your launch template created on the step before
3. On the Network stage, select the app VPC E.g.:stackname_VPC
4. Selct Private1 and Private2 subnets
5. At the Advanced Details, check Receive traffic from one or more load balancers and select the tg-app target group
6. Check Health Check as ELB
7. Go to Review and Create
8. Now, we can create a new CloudWatch alarm and associate with the AutoScaling
9. Go to https://console.aws.amazon.com/cloudwatch
10. Select Alarms and create a new one
11. Select the metrics you want, on this example, we are going to select ApplicationELB -> Per AppELB -> TargetResponseTime
12. Minimize period to 1 minute and on conditions put greater than 0.3
13. Next, create a new SNS topic with your email and create
14. Open a new tab, go to AutoScaling Group that we created
15. Select Scaling Policies and Add Policy
16. Slect Create a scaling policy with steps and select the alarm you created
17. at Take Action Add two new instances and create
18. Edit you AutoScaling group and change Max to 5
19. You can do the same to remove instances when the alarm do not shoot

1. Open the Locust page
2. Create a new test with more users and see the application scaling

• We are not utilizing on this demo, but, CloudFront could minimize the load on the EC2 instances, delivering the static content
• We are utilizing t3.micro instances, we need to do a resizing based on the application behavior and number of users
• To utilize your domain, we could use Route53
• On the Reference links you can find some great getting started guid to help you setup Route53 and CloudFront

1. Delete the resources that you created (Route53, CloudFront, AutoScaling, CloudWatch)
2. Open the CloudFormation console at https://console.aws.amazon.com/cloudformation
3. Select the CloudFormation stack and click on Delete button

• Scaling up to your first 10 million users: https://www.youtube.com/watch?v=Ma3xWDXTxRg
• Getting started AutoScaling: https://docs.aws.amazon.com/autoscaling/ec2/userguide/GettingStartedTutorial.html
• Locust: https://docs.locust.io/en/stable/
• Getting started with CloudFront: https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/GettingStarted.html
• Getting started with Route53: https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/getting-started.html

This sample code is made available under the MIT-0 license. See the LICENSE file.