TL;DR – Lambda-to-Lambda calls are generally a bad idea except for some select use cases, such as: You’re running the Apollo server in a Lambda function. To offload secondary responsibilities to another function by invoking asynchronous (that is, using Event as InvocationType). Avoid synchronous lambda-to-lambda calls If you utter the words “I call a Lambda …
I have been working with a US client to build a first-of-its-kind application to manage your consent to share your data amongst healthcare providers in your state. The project falls within HIPAA, so we need to meet all the HIPAA compliance requirements, including having a full history of the user data. To meet that audit …
My 4-week Production-Ready Serverless workshop is back! With an improved and more comprehensive curriculum based on student feedback from the last run in May, when over 50 students from around the world took part. This is a hands-on workshop where you will learn best practices for building serverless applications by building an e-commerce solution from …
Production-Ready Serverless is back (with improved curriculum)! Read More »
Update 21/06/2020: following lots of feedback and questions on Twitter, I have updated the post to include a few more options. Quite a few clients have asked me “Hey Yan, what API Gateway auth method should I use for this REST API?” so I thought I’d share my answer with everyone here. This is the …
I had been working on a client project where I built the GraphQL backend for a new social network using primarily AppSync, Lambda and DynamoDB. One of the features of the app was to support private messaging between two users. To allow either user to fetch their chat messages in chronological descending order, I modelled …
AppSync: how to compare strings lexicographically in VTL Read More »
TL;DR To make an AppSync DynamoDB resolver throw exceptions on conditional check errors, we need to check $context.error in the response mapping template ourselves. Like this: #if ( $ctx.error ) #if ( $ctx.error.type.equals(“DynamoDB:ConditionalCheckFailedException”) ) $util.error(“your error message”) #else $util.error($ctx.error.message, $ctx.error.type) #end #end $utils.toJson($context.result) And now, the longer version. The problem AppSync lets us perform DynamoDB …
AppSync: how to error on DynamoDB conditional check failures Read More »
Have you been wondering about serverless but just don’t know how and where to start? Maybe you’re already building stuff with serverless, but don’t know if you’re doing it right? Are you unsure about the best practices for testing, monitoring and how to choose between similar services like SNS and EventBridge? I have just …
Skill up your serverless game with my new instructor-led online workshop Read More »
So you have built a serverless application, that, amongst other things, lets you upload images and files to S3. The setup is very simple: API Gateway, Lambda and S3. It took you no time to implement and it works like a dream. You pat yourself on the back for another job well done. One day, …
Hit the 6MB Lambda payload limit? Here’s what you can do. Read More »
Whilst working on a client project, I ran into an interesting problem with AppSync which I couldn’t find an answer after a lot of googling. I hope this article can save you the same pain should you run into the same problem. The problem is that when you have a nullable nested field that you …
AppSync: skipping nullable nested resolvers by returning early Read More »
Lambda invocations are charged in 100ms blocks of execution time. But the cost per 100ms of execution time depends on how much memory you allocate to the function. The higher the memory, the more CPU cycles and network bandwidth, but the higher the cost as well. One of the simplest and most efficient cost optimization …
How to: optimize Lambda memory size during CI/CD pipeline Read More »
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