dazn-lambda-powertools VS middy

I'm a big fan of TypeScript and in fact co-authored a book about it. I don't find myself using Java or Python much, so while I've been interested in Lambda Powertools, I never tried it out until now. Lambda Powertools TypeScript joins middy and DAZN Lambda Powertools in the Lambda tooling space for the Node.js runtime. Two things that differentiate Lambda Powertools TypeScript from comparable libraries are it is sponsored by AWS and it supports decorators.

The next natural step was to look at middleware such as Middy to decorate the main business logic, and allow these tasks to be defined once and used consistently. I remember listening to a Comic Relief talk about their Lambda wrapper back in 2019. Since then, I was introduced by Yan Cui to DAZN Lambda Powertools, which was the inspiration for this new project.

You might be interested in the logger/correlation ID features of https://github.com/getndazn/dazn-lambda-powertools - been super useful for us so far.

Nevertheless, log files are an important resource to debug problems and to get deeper insights into the behavior of a serverless system. Every logged detail might help to identify issues and to fix bugs and problems. Structured logging is important as log files can be analyzed much easier (e.g. with AWS CloudWatch Insights) which will save time and engineering costs. The dazn-lambda-powertools library provides a logger that supports structured logging for Node.js, the AWS Lambda Powertools offer the same for Python and Java.

In many cases, you will have to write the same authorization code in multiple functions. For example, you might want to check that the user is in the requested organization. You can share this code in a middleware. If you are using AWS Lambda, you can rely on middy.

Adding the is-test flag to our object metadata gave us our way of passing some kind of test context into our workload. The next step was to make the Lambda Function capable of discovering the context and then using that to control how it behaves under test. For this we used Middy.

I also decided to use the middy library to add CORS management to our lambda function. This will allow us to call our lambda function from our frontend, without having to worry about CORS.

Is there any equivalent to Node based https://middy.js.org/ for Golang?

And if your requirements were to change at a later date, it’s straightforward to swap out SSM Parameter Store with Secrets Manager there and then. Especially if you’re accessing the relevant service through a middleware layer such as Middy for javascript Lambda functions.

This function uses the Middy middleware engine to handle unhandled errors and add CORS headers in the response.

I mean I'm literally building an AWS lambda function that outputs HTML when it's called via API Gateway. So someone hits https://mydomain.com/mycoolpage, then the MyCoolPage AWS Lambda function is executed and outputs whatever.

If you're interested, I use https://middy.js.org/ as a middleware engine for my AWS lambda functions which I find helpful.

I use the open sourced serverless framework for doing deploys https://www.serverless.com/

middy for lambda-side middleware

That is it from the CDK side. Now let us create the handler and retrieve that secret. I like to use middy which describes itself as "stylish Node.js middleware engine for AWS Lambda". It offers some helpful middlewares like ssm which will help us retrieve and cache values from SSM Parameter Store. (Middy provides various other official middlewares including one for Secrets Manager.) I prefer a middleware for this because it keeps the code for retrieving the secret out of your handler which should deal with actual business logic.