AWS re:Invent 2024 - Building event-driven architectures using Amazon ECS with AWS Fargate

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This blog post summarizes key highlights from the AWS re:Invent 2024 session "SVS339 - Building event-driven architectures using Amazon ECS with AWS Fargate" presented by Eric Johnson and Uma Ramadoss. We'll explore core concepts of event-driven architecture (EDA), integration patterns, and how to leverage AWS Fargate for containerized event-driven applications.

Have you ever wondered how big companies handle millions of user actions at once? At AWS re:Invent 2024, Eric Johnson (Principal Developer Advocate, AWS) and Uma Ramadoss (Principal Specialist Solutions Architect, AWS) tackled this question head-on. They showed how to build systems that can react instantly to all sorts of events using Amazon ECS with AWS Fargate. This blog summarizes key takeaways from their session.

Understanding Event-Driven Architecture (EDA)

To help visualize the concepts of event-driven architecture, let's use an analogy of a bustling city-wide delivery service. This comparison will help us understand how different components of EDA work together to process and respond to events efficiently.

Imagine you're running a delivery service in a large city. Your goal is to efficiently handle packages (events) of various sizes and urgencies, ensuring they reach their destinations quickly and reliably. In this analogy:

  • The city represents your entire system.
  • Packages are the events that need processing.
  • Delivery drivers are like your ECS tasks on Fargate.
  • Different delivery methods (bike, car, truck) represent different compute options.
  • The delivery dispatch center is like Amazon EventBridge, routing packages to the right drivers.
  • Warehouses for storing packages temporarily are like queues (Amazon Simple Queue Service (SQS)) or streams (Amazon Kinesis).
  • GPS tracking and route optimization tools represent orchestration services like AWS Step Functions.

Eric Johnson started by breaking down the basics of event-driven architecture:

  1. What is an event? Think of an event as a digital package saying, "Hey, something just happened!" It's usually a small piece of data (often in JSON format) that tells us about a change in our system. For example, "User just logged in" or "Order was just placed.".
  2. Event-driven architecture simplified: EDA is like a smart delivery system. When something important happens (an event/package arrives), the system tells the right driver/service who needs to handle it. It's that simple: a package arrives, and we deliver it.
  3. Benefits of EDA:
    • It makes systems more flexible. Different delivery drivers can work independently.
    • It's easier to add new features. You just add new drivers for specific types of packages.
    • It can handle sudden spikes in activity better because parts of the system aren't directly tied together.

Integration Patterns for Event-Driven Architecture

Eric and Uma explained two main types of tools for handling events:

  1. Event Routers: These are like smart dispatch centers for your events
    • Event Bus (Amazon EventBridge): Imagine a magical dispatch board where you can post delivery requests, and only the right drivers see them.
    • Topics (Amazon SNS): Think of this as a group announcement to all drivers. One message goes out, and everyone subscribed gets it.
  2. Event Stores: These are like organized warehouses for your events
    • Queues (Amazon SQS): Picture a to-do list of deliveries where each package is handled exactly once, in order.
    • Streams (Amazon Kinesis, Amazon MSK): Think of this as a conveyor belt of packages. Everyone can see everything coming through, but they can choose what to pick up.

Each tool has its strengths, and choosing the right one depends on how you want your system to handle events.

AWS Fargate for Event-Driven Architectures

Uma Ramadoss explained why AWS Fargate is great for event-driven systems:

  1. Serverless compute for containers: Fargate lets you run delivery drivers (containers) without managing vehicles. You focus on your delivery routes, while AWS handles the infrastructure.
  2. Flexible Scaling: Fargate can quickly adjust the number of drivers based on your workload. This is crucial for event-driven systems where demand can vary greatly.
  3. Microservices-Friendly: It's easy to deploy and run small, focused delivery services with Fargate. This aligns well with event-driven architecture principles.
  4. Seamless Integration: Fargate works smoothly with AWS event services like EventBridge and Step Functions, making it easier to build event-driven systems.

EDA Patterns with AWS Fargate

Eric and Uma showcased several ways to implement event-driven architectures using AWS Fargate, each comparable to different aspects of our city-wide delivery service:

  • Standalone Tasks: These are like special, one-time deliveries. Imagine a courier taking a single package from point A to point B, then returning to the depot. In AWS terms, these tasks spin up, do their work (like processing a file upload or running a scheduled job), and then shut down. This makes them cost-effective for intermittent processing needs.
  • Long-Running Services: Think of these as your regular delivery routes that operate continuously. Just as you'd have trucks constantly moving along busy corridors, these services remain available all the time, scaling up or down based on demand. This ensures your application is always responsive to customer needs.
  • Push and Pull-Based Patterns:
    • Push-Based Patterns are like dispatch actively sending out delivery requests to drivers. In AWS, EventBridge pushes events to APIs, with features like rate limiting (to prevent overwhelming drivers) and retry mechanisms (for failed deliveries).
    • Pull-Based Patterns are more like drivers checking a central board for available deliveries. This is similar to processing messages from queues like SQS, where task can scale based on the number of packages waiting to be delivered.
  • Orchestration using AWS Step Functions: This is similar to having a sophisticated logistics system that coordinates complex delivery workflows. It can handle various scenarios - from simple point-to-point deliveries (synchronous patterns) to complex multi-stop routes with real-time updates (asynchronous and callback patterns).
  • New "Activity" Pattern: This is like introducing a new, more efficient way to handle high-volume package sorting and distribution in your delivery hub, designed to process a large number of packages more quickly.
  • Private API Integration: This new feature is comparable to gaining access to private, secure delivery zones (like gated communities or secure office buildings). It allows your delivery service to reach previously inaccessible areas, much like how Step Functions and EventBridge can now invoke APIs within private networks or on-premises systems.

Throughout the presentation, Eric and Uma emphasized how these patterns can be mixed and matched, just as a real delivery service might use different strategies for various types of packages or destinations, creating a flexible, scalable system tailored to specific needs

Best Practices and Considerations

The speakers concluded their presentation by sharing key best practices for building event-driven architectures with AWS Fargate:

  1. Choose the right pattern: Consider factors such as message volume, processing requirements, and desired coupling level.
  2. Implement proper scaling: Adjust your Fargate tasks based on demand using predefined or custom metrics.
  3. Handle failures gracefully: Use dead-letter queues and retry mechanisms, similar to managing misrouted packages in a delivery service.
  4. Cost optimization: Consider using Spot instances for non-time-critical batch processing.
  5. Security: Utilize VPC endpoints and proper IAM roles to ensure your "delivery routes" are secure and accessible only to authorized personnel.

Conclusion

Event-driven architectures offer numerous benefits for building scalable, decoupled systems. Just like a well-organized delivery service can handle packages of all types efficiently, EDA with AWS Fargate, combined with services like EventBridge, Step Functions, and various queuing/streaming options, provides a powerful toolkit for implementing responsive, scalable systems. The speakers provided a resource page, offering additional materials and references for those interested in delving deeper into the topic.

For those interested in diving deeper, the full session recording is available on the AWS YouTube channel, featuring Eric Johnson and Uma Ramadoss's detailed explanations and demonstrations