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[...]

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 » Liked this article? Support me on Patreon and get direct help from me via a private Slack chann[...]

So you have built a serverless application, that, amongst other things, lets you upload images and files to S3. The set-up 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. Until one … Hit the 6MB Lambda payload limit? Here’s what you can do. Read More » Liked this article? Support me on Patreon and get direct help from me via a private Slack channel or 1-2-1 mentoring. Hi, my name is Yan C[...]

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 » Liked this article? Support me on Patreon and get direct help from me via a private Slack channel or 1-2-1 mentoring[...]

In this two-part conversation on Real-World Serverless, I spoke with Joe Emison about his experience with serverless and his latest venture, Branch, a home and auto insurance company that is built fully-serverlessly by a small team. Joe is easily one of the smartest people working with serverless technologies today and I’m very grateful that he … Real-World Serverless: fully-serverless insurance company with Joe Emison Read More » Liked this article? Support me on Patreon and get direct help from me via[...]