AWS Archives

AppSync: how to error on DynamoDB conditional check failures

AppSync, AWS, DynamoDB, GraphQL, Programming

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 …

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Skill up your serverless game with my new instructor-led online workshop

AWS, Lambda, Me, Serverless

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 …

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Hit the 6MB Lambda payload limit? Here’s what you can do.

API Gateway, AWS, Lambda, Programming, Serverless

AWS Lambda has a 6MB limit that applies both to request and response payloads. This can be problematic if you have an HTTP API that allows users to upload images and files to S3. One day, a customer might complain that he couldn’t upload pictures of his cat to your app. In your Lambda logs, …

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AppSync: skipping nullable nested resolvers by returning early

AppSync, AWS, GraphQL, Programming, Serverless

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 …

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How to: optimize Lambda memory size during CI/CD pipeline

AWS, Lambda, Performance, Serverless

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 …

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Real-World Serverless: fully-serverless insurance company with Joe Emison

AWS, Lambda, Me, Real-World Serverless, Serverless

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 …

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Real-World Serverless: state of serverless adoption at Zoopla

AWS, Lambda, Me, Real-World Serverless, Serverless

In the first-ever episode of Real-World Serverless, I spoke with Ricardo Espirito Santo about the state of serverless adoption at Zoopla – how they’re using serverless, their experience with it so far, and the challenges they have faced. Zoopla is a UK company in the real estate industry. They were founded in 2008 and their …

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Announcing the new Real-World Serverless podcast

AWS, Lambda, Real-World Serverless, Serverless

I’m excited to announce that my new podcast Real-World Serverless is LIVE! It’s a brand new podcast where I discuss real-world use cases and challenges with serverless technologies with engineers who are building stuff with them and get their stories from the trenches. The first episode is already live, where I spoke with Ricardo Espirito …

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Diversity tickets for Production-Ready Serverless workshops

AWS, Me, Serverless

By now, you have probably heard that I’m running a number of public workshops all around Europe this year. How could you not, I have hardly shut up about it for a few weeks now :-P To help support the local communities and allow students and other under-represented groups in tech to attend and learn …

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Well-architect your way to better serverless applications

AWS, Serverless

“What are the best practices that I should follow with serverless?” This is easily the most frequently asked question I receive. And I have spent the last couple of years producing contents that document these best practices as they emerge. But hard as I tried, these are scattered over many articles and video courses. While …

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