Serverless Archives

Choreography vs Orchestration in the land of serverless

AWS, EventBridge, Lambda, Serverless, SNS, Step Functions

Choreography and Orchestration are two modes of interaction in a microservices architecture. In orchestration, there is a controller (the ‘orchestrator’) that controls the interaction between services. It dictates the control flow of the business logic and is responsible for making sure that everything happens on cue. This follows the request-response paradigm. In choreography, every service …

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How I scaled an AppSync project to 200+ resolvers

AppSync, AWS, CloudFormation, Programming, Serverless

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 …

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

AppSync, AWS, Programming, Serverless

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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