Mastering AWS AppSync Lambda Resolvers

The AWS AppSync service allows you to create and manage serverless GraphQL and Pub/Sub APIs. GraphQL APIs allow for querying data from multiple data sources using a single endpoint, whereas Pub/Sub APIs allow for real-time data sharing using serverless web socket connections.

You’ll start this Cloud Lab by creating an AppSync API and setting up a Lambda function as its data source. You’ll also go over how to use the Apache Velocity Template Language (VTL) templates and the AWS-provided JavaScript templates as resolvers to resolve GraphQL queries. You’ll use an S3 bucket as the data store for the Lambda data source to simulate how you can use other AWS and external resources not directly supported by AppSync as data sources for your GraphQL API. At the end of the Cloud Lab, you’ll test your GraphQL AppSync API with a full-stack client application.

The following is a high-level architecture diagram of the infrastructure you’ll create in this Cloud Lab:

By the end of this Cloud Lab, you’ll have had hands-on experience developing GraphQL APIs on AWS AppSync and gained a working knowledge of the various resolvers you can use to resolve queries for your AppSync GraphQL API.