For my first few years building serverless applications on AWS, I used AWS CodePipeline coupled with AWS CodeBuild for my CI/CD pipelines. These services were hosted inside AWS where all my infrastructure lived and were functionally good enough for what I wanted to do, so they seemed a good fit. However, last year I decided to switch over to GitHub Actions. I had started using GHA just for Continuous Integration checks on pull requests (linting, unit tests, etc), but I’ve since proceeded to using it for deployments into my AWS environments as well. There were several motivations behind this mo ..read more

If you’re a developer coming to DynamoDB for the first time, a fundamental shift is that there’s now a greater onus on you to ensure the integrity of the data from inside your application’s code. In this article, we’ll explore the different concerns you as a developer need to consider when writing data to DynamoDB. “Integrity” here means that the application data stored across all your DynamoDB tables is both accurate and consistent. Let’s explore these two properties in turn to see where and when they come into play. Accuracy considerations Accuracy is concerned with ensuring that items withi ..read more

Adopting serverless into an organisation brings with it several benefits and challenges. These benefits and challenges hold different weights for different types of organisations. A large enterprise’s primary driver for embracing serverless will probably be different from a bootstrapped SaaS startup’s. Similarly, the main challenges to adoption in both companies will be different. In this article, I’ll focus specifically on the value proposition of adopting serverless to software development agencies. Agency business models The main revenue stream of development agencies comes from building cu ..read more

“The English phrase rule of thumb refers to a principle with broad application that is not intended to be strictly accurate or reliable for every situation.” [Wikipedia] As you gain experience building serverless applications and shipping them to production, you may well find yourself in the role of knowledge benefactor helping out your less experienced team mates. One way to help with these efforts is to build up a bank of “rules of thumb” within your team. While there are many general software development rules of thumb that they’ll already be aware of, the serverless space is still young ..read more

AWS recommend you don’t connect Lambda functions to a VPC unless absolutely necessary. This is solid advice because doing so brings several limitations that a standard function doesn’t suffer from. One of these limitations is that your Lambda function can no longer access the internet. What many people don’t realise is that communicating with other AWS resources inside your account from your function also requires internet access (think S3, SNS, SQS, etc). This makes many common VPC use cases tricky to implement with Lambda. Let’s take the example of a scheduled Lambda function that runs a dai ..read more

So you’re building a REST API and you need to add support for uploading files from a web or mobile app. You also need to add a reference to these uploaded files against entities in your database, along with metadata supplied by the client. In this article, I’ll show you how to do this using AWS API Gateway, Lambda and S3. We’ll use the example of an event management web app where attendees can login and upload photos associated with a specific event along with a title and description. We will use S3 to store the photos and an API Gateway API to handle the upload request. The requirements are ..read more

DynamoDB is big right now. Within the past six months its popularity seems to have exploded, at least in the online circles I frequent. I have previously compared multi- and single- table DynamoDB data modelling approaches where I was somewhat skeptical about the widespread adoption of the single-table approach especially for apps in the early stages of development. Since writing that article, the landscape has changed and some of my concerns around the single table approach have lessened. A proper community is forming and I can see standard practices starting to emerge. Alex DeBrie’s recently ..read more

If you’re building serverless applications in a large organisation where multiple teams are involved in their ongoing development and support, you may find yourself needing to answer questions such as: Who owns this resource? What application does it belong to? Who should we call when the application is broken? Who should pay for this resource? Which applications are driving our costs? Do access controls secure this resource appropriately? How much risk does our Cloud deployment have? Where is that risk concentrated? Which security improvements reduce our risk the most? If so, then you shoul ..read more

Every now and again, I like to share a short article review with you from others in the serverless community. These will be pieces that I refer to often, either for inspiration or reference; some will be technical, others will be more strategic. Today’s article is Serverless is a State of Mind by Ben Kehoe. I love this piece from Ben as it acknowledges all the attributes that folks consider to be core to serverless as important but posits that they are “not the point”. He then distils serverless down to this essence: “Focus is the Why of Serverless” Focus is a critical attribute both at an i ..read more

I’ve published a few articles recently on the topic of communication patterns within serverless applications. It’s an area where serverless can really shine, but it also takes some time to get used to, especially for folks with less experience in working with distributed systems. Jeremy Daly very kindly invited me onto the Serverless Chats podcast last week where we dived into this area in more detail. The episode just went live this morning. He also recorded the video of our chat (thankfully before my home office was taken over by my eldest daughter!), so you can check it out on YouTube. Here ..read more