AWS AppSync Cheat Sheet

• A serverless GraphQL and Pub/Sub API service that streamlines the development of modern web and mobile applications

  • AppSync GraphQL APIs – provides a unified endpoint for securely querying and updating data from multiple databases, microservices, and APIs

  • AppSync Pub/Sub APIs – data updates are automatically published to subscribed API clients via serverless WebSockets connections.

Concepts

• GraphQL

  • It allows apps to retrieve data from servers.

  • The GraphQL proxy is a component that runs the GraphQL engine to process requests and map them to logical functions for data operations or triggers.

  • Three level operations:

    • Query – read-only fetch

    • Mutation – write followed by a fetch

    • Subscription – long-lived connection for receiving data

  • The operations are exposed via a schema that defines the capabilities of an API.

  • A schema is made up of types, which can be root or user-defined.

  • To build a GraphQL API, you need to have the following:

    • GraphQL Schema – each GraphQL API is defined by a single GraphQL schema.

    • Data Source – AWS resources that GraphQL APIs can interact with.

    • Resolvers – uses mapping templates to convert a GraphQL expression into a format that the data source can use.

      • Unit resolver – performs a single operation against a predefined data source.

      • Pipeline resolver – executes multiple operations against multiple data sources.

  • You can use a GraphQL client or HTTP to connect to a GraphQL API.

  • GraphQL API Caching per Field — You can apply caching to specific resolvers or fields rather than the entire query.

• Real-time data

  • By specifying a GraphQL schema directive on a mutation, you can make any data source in AWS AppSync real time.

  • Data filtering

    • Basic – subscription query filtering based on client-defined arguments.

    • Enhanced – filtering based on logic defined centrally in the backend of the AWS AppSync.

  • You can also use specific filtering logic to forcefully unsubscribe and close a WebSocket connection from a connected client.

• Configuration and settings

  • You can cache frequently requested data to reduce the load on your resolvers.

  • By compressing API responses, you can download content faster and save money on data transfer fees.

  • Supports custom domain names for your API.

• Resolvers

  • JavaScript Resolvers — AppSync now supports JS-based resolvers (in addition to VTL), enabling more flexible logic and easier debugging.

  • Server-Side Webhooks — You can configure AppSync to accept events from external HTTP sources via webhooks as part of a resolver flow.

AWS AppSync Monitoring

• Use Amazon CloudWatch Logs to monitor your AWS AppSync GraphQL API and debug request issues.

• You can use AWS X-Ray to trace GraphQL requests in AWS AppSync.

• With AWS CloudTrail, you can log AWS AppSync API calls.

AWS AppSync Security

• In your API or CLI call, you can specify which authorization type you want:

  • API_KEY

  • AWS_LAMBDA

  • AWS_IAM

  • OPENID_CONNECT

  • AMAZON_COGNITO_USER_POOLS 

• Using schema directives, you can specify additional authorization modes at the schema level.

• You can use AWS WAF to configure a set of rules to protect your web applications and APIs from attacks.

• Multiple API Authorization Modes Simultaneously

  • You can combine modes (e.g., IAM + Cognito + API Key) at the resolver or operation level.

• Custom Headers & Context Mapping

  • Resolvers can pass custom request headers to downstream APIs for multi-tenant or auditing purposes.

• GraphQL API Versioning

  • AppSync supports versioning of schemas when using code generation or branching via Amplify or Git-integrated workflows.

AWS AppSync Pricing

• You are charged for the following:

  • Query and data modification operations.

  • Performing real-time updates on your data.

  • Minutes of connection to AppSync.

  • Dedicated cache instance.

AWS AppSync Cheat Sheet References:

https://aws.amazon.com/appsync/
https://docs.aws.amazon.com/appsync/latest/devguide/what-is-appsync.html