One of my favourite questions from the November cohort of Production-Ready Serverless [1] is, "How do you handle e2e tests involving multiple services across bounded contexts?" In a microservices environment, testing user journeys that span across multiple bounded contexts requires collaboration and a clear delineation of responsibilities. Depending on how your organisation is structured, different teams are responsible for testing parts or the entirety of the user journey. For example... The...
19 days ago • 4 min read
The ability to invalidate a user's session with immediate effect is a common enterprise requirement. For example: If a user's credentials are compromised, we need to immediately revoke the user's access and force the user to change credentials. If an employee is terminated or an external contractor's access is revoked, their session should be invalidated immediately to prevent misuse. Many regulations mandate strict access controls and the ability to prevent unauthorized access in real time....
24 days ago • 3 min read
So that's it for this year's re:Invent. Werner delivered his usual insightful keynote and shared some key lessons in dealing with complexity and warning signs to look out for. As Werner said, the number of moving parts is not a good measure of complexity on its own. And that's something so many people get wrong about serverless - that they judge complexity by the no. of components on an architecture diagram. Ok, on with the serverless announcements. Aurora DSQL (pronounced "dee-sequel")...
29 days ago • 2 min read
One of the most misunderstood aspects of Lambda is how throttling applies to async invocations. Or rather, how it doesn't! Every Lambda invocation has to go through its Invoke API [1], whether you're invoking the function directly or through an event source such as API Gateway or SNS. With the Invoke API, you can choose invocationType as either "RequestResponse" (i.e. synchronous) or "Event" (i.e. asynchronous). Synchronous invocations With synchronous invocations, throttling limits are...
about 2 months ago • 2 min read
When it comes to building event-driven architectures on AWS, EventBridge has become the de facto service for ingesting, filtering, transforming and distributing events to their desired destinations. It provides a standard envelope encapsulating each event, including metadata like the source, detail type, and timestamp. These fields are useful, but I'm gonna give you several reasons why you should wrap your event payload in its own envelope. For example, like this: 1. Clear separation between...
2 months ago • 3 min read
Years ago, I worked at a large e-commerce company that was one of the biggest food delivery services in the UK. They did something very interesting - they regularly ran load tests against production using fake orders. As a partial observer, here's what I think we can learn from this practice and how it partially caused the biggest outages they ever experienced (but not from the load test itself!). Load Testing in production As a food delivery service, they experienced large traffic spikes...
2 months ago • 5 min read
Serverless is an incredible paradigm, but performance tuning sometimes feels like a black box. You have no control over the infrastructure, but that doesn’t mean you can’t optimize. In this post, let’s look at five ways to take serverless performance to the next level. 1. Right-size Lambda functions With Lambda, you have one lever to control the power and cost of your functions — its memory setting. Both CPU and network bandwidth are allocated proportionally to a function’s memory allocation....
3 months ago • 4 min read
Software systems are getting bigger and more complex. And we are constantly looking for ways to test code in production without risking user experience. Canary deployments is a popular mechanism for rolling out changes incrementally, allowing us to limit the blast radius in case something goes wrong. However, they’re not without limitations. Canary deployments essentially sacrifice a small portion of users for the greater good. But what if you want to gain insights without impacting any real...
3 months ago • 3 min read
Every software engineer should learn about the Actor Model, even if they don't work with Erlang, Elixir or Akka. It opens up your mind to a new way of thinking about computation and concurrency. And what better way to learn than to hear from its inventor, Carl Hewitt (R.I.P)? This conversation between Carl, Erik Meijer (of the Rx fame) and Clemens Szyperski is a must-see! An actor is the fundamental unit of computation which embodies the 3 things – processing, storage and communications –...
3 months ago • 1 min read
