AppSync Transformer Construct for AWS CDK

Why This Package

In April 2020 I wrote a blog post on using the AWS Cloud Development Kit with AppSync. I wrote my own transformer in order to emulate AWS Amplify's method of using GraphQL directives in order to template a lot of the Schema Definition Language.

This package is my attempt to convert all of that effort into a separate construct in order to clean up the process.

How Do I Use It

Example Usage

API With Default Values

import { AppSyncTransformer } from 'aws-cdk-appsync-transformer';
...
new AppSyncTransformer(this, "my-cool-api", {
    schemaPath: 'schema.graphql'
});

schema.graphql

type Customer @model
    @auth(rules: [
        { allow: groups, groups: ["Admins"] },
        { allow: private, provider: iam, operations: [read, update] }
    ]) {
        id: ID!
        firstName: String!
        lastName: String!
        active: Boolean!
        address: String!
}

type Product @model
    @auth(rules: [
        { allow: groups, groups: ["Admins"] },
        { allow: public, provider: iam, operations: [read] }
    ]) {
        id: ID!
        name: String!
        description: String!
        price: String!
        active: Boolean!
        added: AWSDateTime!
        orders: [Order] @connection
}

type Order @model
    @key(fields: ["id", "productID"]) {
        id: ID!
        productID: ID!
        total: String!
        ordered: AWSDateTime!
}

Supported Amplify Directives

Tested:

• @model
• @auth
• @connection

Experimental:

• @key
• @versioned
• @function
  • These work differently here than they do in Amplify - see Functions below

Not Yet Supported:

• @searchable
• @predictions
• @http

Authentication

User Pool Authentication

const userPool = new UserPool(this, 'my-cool-user-pool', {
    ...
})
...
const userPoolClient = new UserPoolClient(this, `${id}-client`, {
    userPool: this.userPool,
    ...
})
...
new AppSyncTransformer(this, "my-cool-api", {
    schemaPath: 'schema.graphql',
    authorizationConfig: {
        defaultAuthorization: {
            authorizationType: AuthorizationType.USER_POOL,
            userPoolConfig: {
                userPool: userPool,
                appIdClientRegex: userPoolClient.userPoolClientId,
                defaultAction: UserPoolDefaultAction.ALLOW
            }
        }
    }
});

IAM

Unauth Role: TODO

Auth Role: Unsupported (for now?). Authorized roles (Lambda Functions, EC2 roles, etc) are required to setup their own role permissions.

Functions

Fields with the @function directive will be accessible via api.outputs.FUNCTION_RESOLVERS. It will return an array like below.Currently these are not named and do not specify a region. There are improvements that can be made here but this simple way has worked for me so I've implemented it first. Typically I send all @function requests to one Lambda Function and have it route as necessary.

[
  { typeName: 'Query', fieldName: 'listUsers' },
  { typeName: 'Query', fieldName: 'getUser' },
  { typeName: 'Mutation', fieldName: 'createUser' },
  { typeName: 'Mutation', fieldName: 'updateUser' }
]

DataStore Support

1. Pass syncEnabled: true to the AppSyncTransformerProps
2. Generate necessary exports (see Code Generation below)

Code Generation

I've written some helpers to generate code similarly to how AWS Amplify generates statements and types. You can find the code here.

Versioning

I will attempt to align the major and minor version of this package with AWS CDK, but always check the release descriptions for compatibility.

I currently support

Limitations

Contributing

See CONTRIBUTING for details

License

Distributed under Apache License, Version 2.0