Serverless Archives

How to handle serverful resources when using ephemeral environments

I’m a big fan of using ephemeral (or temporary) environments when I’m building serverless architectures. I have written about this practice before and I believe it’s one of the most important practices that have co-evolved with the rise of serverless technologies. It takes advantage of the pay-per-use pricing model offered by many serverless technologies such …

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This is why you should keep stateful and stateless resources together

AWS, CloudFormation, Serverless

Update 24/05/2023: As Lee James Gilmore pointed out on Twitter, the unit of deployment of CDK is the CDK app. A CDK app can contain multiple CloudFormation stacks and they can be changed together (in a single commit) and deployed together. And that’s absolutely fine and compatible with what I’m advocating for in this post. …

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A practical guide to testing AWS Step Functions

AWS, Serverless, Step Functions, Testing

Testing Step Functions can be a daunting task. However, with a little preparation and effort, the testing process can be simplified and streamlined. In this article, we will provide a practical strategy on how to test Step Functions. So let’s start by setting the stage and introducing the players. What makes Step Functions hard to test? …

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The biggest preinvent serverless announcements you may have missed

AppSync, AWS, EventBridge, Lambda, Serverless, SNS

re:Invent is almost upon us. Judging by the things that had been announced ahead of re:Invent, one can’t help but be excited about the main event itself! Here is a list of the serverless-related announcements so far that you should know about. Payload-based message filtering for Amazon SNS Here’s the official announcement. This is arguably the …

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My testing strategy for serverless applications

AWS, Lambda, Programming, Serverless

Testing serverless architectures doesn’t have to be hard, and it doesn’t have to be slow.

Let me share my approach with you, and show you how I achieve a fast feedback loop by writing remocal tests against ephemeral environments, and how you can turbocharge your workflow as well. Once you “get it”, serverless testing can be a joy :-)

Group-based auth with AppSync Lambda authoriser

AppSync, AWS, Programming, Security, Serverless

AWS AppSync added support for Lambda authorizers on 30th July 2021 and it made it much easier to implement group-based authorization with 3rd party identity services. Group-based auth with AppSync and Cognito I previously wrote about how you can secure multi-tenant applications with AppSync and Cognito. Where you can use custom attributes to capture the tenant …

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How to handle client errors gracefully with AppSync and Lambda

AppSync, AWS, Lambda, Programming, Serverless

With API Gateway and Lambda, you can handle client errors gracefully by returning a 4xx response. module.exports.handler = async (event) => { // run validation logic return { statusCode: 400 } } This way, we can communicate clearly to the client that there’s a problem with its request. It also lets the Lambda invocation complete …

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Lambda layer: not a package manager, but a deployment optimization

AWS, Lambda, Programming, Serverless

It’s been two years since I last wrote about Lambda layer and when you should use it. Most of the problem I discussed in that original post still stands: It makes it harder to test your functions locally. You will still need those dependencies to execute your function code locally as part of your tests. …

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Building a custom IAM system has made me appreciate AWS IAM even more

AppSync, AWS, Lambda, Programming, Serverless

In the last post I discussed my preferred approach for modelling multi-tenant applications with AppSync and Cognito. This approach supports the common requirements in these applications, where there are a number of distinct roles within each tenant. This approach (and others like it) works great when the tenants are isolated. But what if they are …

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How to model one-to-many relationships with AppSync and DynamoDB

AppSync, AWS, DynamoDB, Programming, Serverless

Thank you to Josh for asking this question on the AppSync Masterclass forum. His original question goes like this: Let’s say I want to add a one-to-many relationship from Profile to a new property called “Tag” (a complex object with “name” and “color” properties) so a user can define their own Tags. I would also like a …

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