Serverless Archives

AppSync: how to inject table names into DynamoDB batch & transact operations

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 …

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Are Lambda-to-Lambda calls really so bad?

AWS, Lambda, Programming, Serverless

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 …

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Production-Ready Serverless is back (with improved curriculum)!

AWS, Lambda, Me, Serverless

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 …

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How to choose the right API Gateway auth method

API Gateway, AWS, Programming, Security, Serverless

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 …

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AppSync: how to compare strings lexicographically in VTL

AppSync, AWS, Serverless

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 …

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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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