In modern cloud architecture, "it works on my machine" isn't enough. When your application scales to millions of users across the globe, you need a testing strategy that reflects that reality. However, building a home-grown distributed testing infrastructure can be a massive engineering undertaking.
This is where the AWS Distributed Load Testing (DLT) solution comes in. In this post, we’ll explore what this solution offers, how it works, and how you can use it to simulate massive, multi-region traffic.
What is the AWS Distributed Load Testing Solution?
The AWS Distributed Load Testing solution is an AWS Solutions Implementation that automates the testing of software applications at scale and at load. Instead of managing a fleet of EC2 instances manually, this solution provides a pre-built framework to:
- Generate Massive Scale: Simulate thousands of concurrent users.
- Go Global: Launch test runners across multiple AWS regions to simulate realistic geographic traffic patterns.
- Visualize Results: A built-in web console provides real-time metrics and historical data for every test run.
Core Architecture
The solution leverages Amazon ECS on AWS Fargate to run containerized test engines. This serverless approach means you only pay for the compute while the test is running. It supports popular open-source engines like JMeter, Locust, and K6.
Why Use It?
While many developers use simple tools for local benchmarking, the DLT solution is designed for high-concurrency scenarios that local machines cannot handle.
- CloudFront & CDN Validation: By downloading large assets through various edge locations, you can validate CDN caching behavior and performance under stress.
- Multi-Region Simulation: Test how your application handles latency and traffic spikes originating from different parts of the world simultaneously.
- Predictive Cost Modeling: By generating realistic egress patterns, teams can better estimate data transfer costs before a major product launch.
Automation & Scheduling
One of the most powerful features of the DLT solution is the ability to move beyond manual execution. Performance testing is most effective when it is consistent and predictable.
Scheduled and Recurring Tests
You don't need to be at your desk to trigger a massive load test. The DLT console allows you to:
- Run Once at a Specific Time: Schedule a test to run during off-peak hours or ahead of a planned maintenance window.
- Recurring Schedules: Set up tests to run daily, weekly, or monthly to ensure no performance regressions have been introduced into your codebase.
- CRON Job Integration: For advanced automation, the solution supports standard CRON expressions. This is ideal for engineering teams who want to align performance tests with specific deployment cycles or complex internal schedules.
How to Get Started
1. Deployment
The quickest way to get started is using the AWS CloudFormation templates provided in the official documentation.
- AWS Solutions Implementation Guide
- Source Code (GitHub)
- Auxiliary Templates for easy multi-region deployment (GitHub)
2. Setting Up Your First Test
Once the stack is deployed, you will receive a URL for your private DLT Web Console.
- Authenticate: Log in using the credentials created during the CloudFormation deployment.
-
Define the Endpoint: Enter the target URL (e.g.,
https://dlt1.csne.io/test-5gb.bin). -
Configure Parameters: * Tasks: Number of Fargate containers (e.g., 100).
- Concurrency: Sessions per task (e.g., 5).
- Regions: Select the regions for load generation (e.g., us-east-1, us-east-2, us-west-1, us-west-2).
- Set the Schedule: Choose "Run Now" or configure your Schedule/CRON settings for later execution.
- Monitor Results: Track response times, success rates, and bandwidth in real-time or review the reports later.
Example Configuration Spotlight
To simulate realistic traffic, your configuration should look similar to the following:
| Parameter | Configuration |
|---|---|
| Method | GET |
| Endpoint | https://cdn.example.com/assets/video-part-1.bin |
| Tasks | 100 |
| Concurrency | 5 |
| Geographic Scope | All 4 US Regions |
Power at Scale: Real-World Performance
When scaled appropriately, the AWS DLT solution can generate massive throughput. In a recent baseline test using 100 tasks with 5 concurrent sessions distributed across all 4 US regions, we observed the solution's true potential.
By targeting a series of 5GB dummy files across multiple CloudFront distributions, the test infrastructure successfully pushed the boundaries of standard egress:
- Peak Performance: CloudFront egress reached 50+ TB per 5-minute interval.
- Sustained Load: The system maintained a steady-state egress of 20TB for the duration of the test.
This level of performance is critical for validating that your CDN configurations, origin shielding, and bandwidth quotas are sufficient for high-traffic events like global product launches or major media broadcasts.
Example Use Cases
Scenario A: High-Bandwidth Egress Testing
If your product serves large binaries (e.g., video chunks or software installers), you can use DLT to pull files of varying sizes (1GB to 5GB) through Amazon CloudFront. This allows you to measure the impact of sustained high-bandwidth egress on your infrastructure and budget.
Scenario B: API Stress Testing with JMeter/K6
Beyond simple GET requests, you can upload custom scripts. For instance:
-
JMeter: Upload a
.jmxfile to simulate complex user flows involving authentication and database writes. - K6: Use JavaScript-based scripts to define "Sustained Load" vs. "Spike" scenarios, allowing you to see how your auto-scaling groups react to sudden surges.
Summary
The AWS Distributed Load Testing solution takes the heavy lifting out of performance engineering. By moving from local "one-off" tests to a distributed, automated, and scheduled framework, you ensure that your application is ready for the real world—before the real world arrives.
For more detailed configuration templates and advanced deployment options, check out the AWS DLT Documentation.
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