I have been working on a large AppSync project for a client these past few months. The initial version of the app was built in just a few weeks, but the client has commissioned additional features and the project has kept growing. At the time of writing, this project has over 200 AppSync resolvers and …
How I scaled an AppSync project to 200+ resolvers Read More »
When working with CloudFormation, AWS recommends not to give explicit names to resources and let CloudFormation name them for you. This has several advantages: It’s harder for attackers to guess resource names such as S3 buckets or DynamoDB tables. You can deploy the same stack multiple times to the same account. This is useful when …
AppSync: how to inject table names into DynamoDB batch & transact operations Read More »
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 »
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, …
Hit the 6MB Lambda payload limit? Here’s what you can do. Read More »
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