Last week, someone asked me at the AWS User Group in The Hague “Is caching still relevant for serverless applications?” The assumption here is that Lambda auto-scales by traffic, so do we still need to worry about caching? And if so, where and how do we implement caching? So let’s break it down. Caching is …
All you need to know about caching for serverless applications Read More »
Update 06/04/2023: It’s been 3 years since I originally wrote this blog post and I want to share some updates to my thinking because this blog post was referenced in a recent PR for the serverless-esbuild project. Thanks, Fredrick for messaging me about this. Let me start by saying that the risks I outlined in …
Should you pack the AWS SDK in your deployment artefact? Read More »
Update 17/09/2019: based on feedback, I added a few more alternatives that do not require you to deploy additional Lambda functions to the e2e-test stage. Scroll to the end to find out more. Being event-driven is a key characteristic of a serverless architecture. Often our Lambda functions would publish events to SNS topics or Kinesis …
How to include SNS and Kinesis in your e2e tests Read More »
Hi, welcome to another weekly update! I’ve been busy since the last time we were here, and I have lots of cool updates to share with you. New blog posts How to use the power of CloudFormation custom resources for great good. In this post, I described an approach for invoking a Lambda function as …
Disclaimer: if you’re new to CloudFormation custom resources, then I recommend you start by reading this excellent post by Alex Debrie first. Custom resources bring a whole new dimension to CloudFormation and enable some fascinating use cases. For example: provision DataDog dashboards as part of your CloudFormation stack run a load test every time you …
How to use the power of CloudFormation custom resources for great good Read More »
Recently, I have been helping a client implement an event-sourced system. In the process, I put together a very simple demo app to illustrate how one could build such a system using Lambda and DynamoDB. The source code is available on GitHub here. Before you go ahead and read all about the demo app, I …
A simple event-sourcing example with snapshots using Lambda and DynamoDB Read More »
A client asked me the other day: “What happens to the running executions when I update a state machine?” Sadly, the answer is likely that existing executions would break if you have changed the input/output of the Lambda functions they call. The solution is to use specific versions or aliases of the functions instead. But …
How to do blue-green deployment for Step Functions Read More »
The Serverless framework lets you reference external JSON, YML and JS files using the syntax ${file:(fileName):propertyName}. However, you can’t customize these external config files with runtime arguments. A reader asked me: “I have this boilerplate that is repeated many times in my serverless.yml, how do I reuse the boilerplate but override only specific fields?” It’s …
How to make serverless framework boilerplates customizable Read More »
I have some exciting news to share with you about the Serverless Step Functions plugin. One of the main pain points of using the plugin was that you needed to use fully-formed ARNs. We addressed this in v1.18.0 by supporting CloudFormation intrinsic functions Fn:GetAtt and Ref. This makes it possible for you to reference a …
Serverless Step Functions: no more leaky abstractions Read More »
Many clients have asked me “how do I record custom metrics from Lambda?”. Generally speaking, you can either: Publish custom metrics synchronously – e.g. send them at the end of an invocation. Publish custom metrics asynchronously by writing them to stdout first and then extracting them from CloudWatch Logs. Problems with sending custom metrics synchronously …
Introducing a better way to record custom metrics Read More »
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