Intro

Leverage Locust load testing on your own AWS Infrastructure.

It uses docker compose ecs to deploy:

• https://docs.docker.com/cloud/ecs-integration/
• https://docs.docker.com/cloud/ecs-compose-features/
• https://docs.aws.amazon.com/AmazonECS/latest/developerguide/cmd-ecs-cli-compose-parameters.html
• https://docs.docker.com/cloud/ecs-compose-examples/

Motivation

Load testing is really important to prevent production errors and to see how web services perform given a scenario (number of users/requests). Locust is a popular load testing tool used by thousands of users and has a great community/support.

AWS ECS can be easily used to deploy containers in AWS - which is a good fit to deploy multiple workers as Fargate Tasks for Locust.

Components

The solution has a stack located under infra folder which has a CDK stack that creates the ECR repository.

Docker ECS Deploy creates all the resources (Load Balancer, Listeners/Target Groups, ECS Cluster/Fargate Tasks) under the hood. All we need to do is to define the docker-compose.yaml file.

locustfile.py has a single task that have a simple hello world task. Check Locust Docs to check how you can customize your tests.

Install

Requirements

NodeJS, Docker, and a Valid AWS Account.

Scripts

• convert: outputs the cloud formation that will be deployed by AWS ECS
• up: Deploy the Application to AWS Infrastructure
• setup:aws: Creates a local profile with the AWS details defined in the environment variables
• create-ecs-context: Create a new ECS docker context
• reset-docker-context: Reset the docker context
• ecr-push-image: Push the locust image to ECR
• set-ecs-context: Switch docker context to ECS

Steps

1. Setup AWS Credentials

• Access AWS Console and create a new IAM user with ECR permissions and the permissions described here https://docs.docker.com/cloud/ecs-integration/#requirements.
• Copy the Access and Secret keys to the environment variables. You also need to copy the Aws Account Id and the region.
• In the root folder run yarn setup:aws - this will set up a new aws cli profile locust on your local computer.

2. Deploy CDK Stack with the ECR Repository

• Navigate to infra and run yarn or npm i to install de dependencies. Run the deploy script to deploy the stack.
• Once the stack is deployed copy the ECR_URI to the environment variable AWS_ECR_URI

3. Push the docker image to ECR Repository

• Navigate to the root folder and run yarn ecr-push-image to push the Docker Image to ECR. Once it's done replace the ECR_IMAGE_URI and IMAGE_TAG in docker-compose.yaml file with the deployed image details.

4. Deploy docker-compose to AWS ECS

• Run yarn up or docker compose up to deploy the images to AWS ECS. In this step, AWS will create a new stack and all the resources needed (Load Balancer, ECS, etc.)

5. Accessing Locust UI (master node)

• Go to AWS Console and check the Load Balancer DNS address and access it using the port 8089 and you will see a web interface that can be used to start your tests.
• You can add as many workers as you want by modifying the docker-compose.yaml and adding a new worker. You will see a similar UI to this:

Removing Resources

• AWS will create two Cloudformation Stacks - one defined by aws docker-compose ecs deploy and the other defined by CDK. Remember to remove them once you're done to avoid unexpected costs.
• You can remove the stack created by CDK navigating to infra and running yarn destroy

Limitations & Future Improvements

This project was developed as a simple demo to show how it's possible to easily leverage a robust load testing solution in our own cloud environment, but has several limitations and improvements, for example:

• This version uses the default options used by aws ecs compose. If you want to customize it please check the options available here
• Tag Version is manually defined in .env at the moment unless you're using CI/CD that has a unique environment variable identifying the commit id/deploy id or something like this. Whenever you make changes in locust python test files you need to change this environment variable and push the image to ECR again.
• The AWS docker-compose abstracts a lot of resources in the infrastructure (Load Balancer, ECS CPU, memory) - some settings can be changed as described here but maybe a CDK template that creates the ECS Task/Load Balancer could be used to customize the solution.
• All the commands to set up and deploy could be simpler.
• As future plan, I will create a CDK Template to deploy the infrastructure instead of using ECS docker-compose deploy.

Feel free to use, modify and ask questions!