When it comes to building GraphQL servers, AWS AppSync is my favourite solution. It is a managed, serverless service that makes it easy to build efficient and scalable APIs.
Why AWS AppSync?
I really like AppSync for a few simple reasons:
- Managed & Serverless: It handles so much for you, like observability and security.
- JavaScript Runtime: I can write my resolvers in JavaScript, which feels much more natural.
- Fast Performance: There are no cold starts, so things run quickly.
- Advanced Features: Built-in features like caching, DeltaSync, and conflict resolution really help with complex tasks.
But here’s the catch: setting up an API with AppSync means I have to write the GraphQL schema, create resolvers for every operation, and then configure all the AWS resources. Even small changes can turn into a headache.
About Amplify
Another solution that uses AppSync under the hood is Amplify, a toolchain developed by the AWS folks designed to help developers get started with their services. While I like their approach of describing the entire schema via a config file, it does come with a set of design decisions that I don’t fully agree with, most notably:
- It creates one DynamoDB table per model;
- It uses VTL (Velocity Templating Language) to generate resolvers, which makes it hard to customise;
- It generates complex pipelines for each resolver—good luck finding the right one to modify!
Luckily, Amplify is an open-source project, so we can take a look at how they do things.
The AppSync GraphQL Transformer Library
Inspired by the idea of declaring models and relationships with simple directives, and having a code generator take care of the rest, I decided to build my own library for AppSync.
Although I want it to be as extensible as possible, I had to make some design decisions right away. Here’s what I’m aiming for:
- DynamoDB Single Table Design: Use a single table as the primary data source.
- JS Runtime Resolvers: Generate JavaScript runtime resolvers that are easy to modify or replace with custom implementations.
- TypeScript Support: Generate schema types and handle transpiling and bundling of resolver code.
- GraphQL Best Practices: Follow best practices, including Connections and Global Object IDs.
I aim to create it as a standalone library, independent of any infrastructure-as-code solution. However, to make it easier to work with, I'm also developing a CDK construct that will provision all the necessary resources for you.
What’s Next?
The project is currently in progress and not yet open source. I plan to have an experimental release ready in a couple of days, and then I’ll make the repository public on Saapless.
Stay tuned for more updates, and happy coding!
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