feat(appsync): import existing graphql api

packages/@aws-cdk/aws-appsync/README.md

@@ -63,7 +63,7 @@ const demoTable = new db.Table(stack, 'DemoTable', {
   },
 });
 
-const demoDS = api.addDynamoDbDataSource('demoDataSource', 'Table for Demos"', demoTable);
+const demoDS = api.addDynamoDbDataSource('demoDataSource', demoTable);
 
 // Resolver for the Query "getDemos" that scans the DyanmoDb table and returns the entire list.
 demoDS.createResolver({
@@ -82,6 +82,24 @@ demoDS.createResolver({
 });
 ```
 
+## Imports
+
+Any GraphQL Api that has been created outside the stack can be imported from 
+another stack into your CDK app. Utilizing the `fromXxx` function, you have 
+the ability to add data sources and resolvers through a `IGraphQLApi` interface.
+
+```ts
+const importedApi = appsync.GraphQLApi.fromGraphQLApiAttributes(stack, 'IApi', {
+  graphqlApiId: api.apiId,
+  graphqlArn: api.arn,
+});
+importedApi.addDynamoDbDataSource('TableDataSource', table);
+```
+
+If you don't specify `graphqlArn` in `fromXxxAttributes`, CDK will autogenerate
+the expected `arn` for the imported api, given the `apiId`. For creating data 
+sources and resolvers, an `apiId` is sufficient.
+
 ## Permissions
 
 When using `AWS_IAM` as the authorization type for GraphQL API, an IAM Role

packages/@aws-cdk/aws-appsync/lib/data-source.ts

@@ -3,7 +3,7 @@ import { IGrantable, IPrincipal, IRole, Role, ServicePrincipal } from '@aws-cdk/
 import { IFunction } from '@aws-cdk/aws-lambda';
 import { Construct, IResolvable } from '@aws-cdk/core';
 import { CfnDataSource } from './appsync.generated';
-import { GraphQLApi } from './graphqlapi';
+import { IGraphqlApi } from './graphqlapi-base';
 import { BaseResolverProps, Resolver } from './resolver';
 
 /**
@@ -13,11 +13,13 @@ export interface BaseDataSourceProps {
   /**
    * The API to attach this data source to
    */
-  readonly api: GraphQLApi;
+  readonly api: IGraphqlApi;
   /**
    * The name of the data source
+   *
+   * @default - id of data source
    */
-  readonly name: string;
+  readonly name?: string;
   /**
    * the description of the data source
    *
@@ -91,7 +93,7 @@ export abstract class BaseDataSource extends Construct {
    */
   public readonly ds: CfnDataSource;
 
-  protected api: GraphQLApi;
+  protected api: IGraphqlApi;
   protected serviceRole?: IRole;
 
   constructor(scope: Construct, id: string, props: BackedDataSourceProps, extended: ExtendedDataSourceProps) {
@@ -100,15 +102,15 @@ export abstract class BaseDataSource extends Construct {
     if (extended.type !== 'NONE') {
       this.serviceRole = props.serviceRole || new Role(this, 'ServiceRole', { assumedBy: new ServicePrincipal('appsync') });
     }
-
+    const name = props.name ?? id;
     this.ds = new CfnDataSource(this, 'Resource', {
       apiId: props.api.apiId,
-      name: props.name,
+      name: name,
       description: props.description,
       serviceRoleArn: this.serviceRole?.roleArn,
       ...extended,
     });
-    this.name = props.name;
+    this.name = name;
     this.api = props.api;
   }
 

packages/@aws-cdk/aws-appsync/lib/graphqlapi-base.ts

@@ -0,0 +1,193 @@
+import { ITable } from '@aws-cdk/aws-dynamodb';
+import { IFunction } from '@aws-cdk/aws-lambda';
+import { CfnResource, IResource, Resource } from '@aws-cdk/core';
+import { DynamoDbDataSource, HttpDataSource, LambdaDataSource, NoneDataSource } from './data-source';
+
+/**
+ * Optional configuration for data sources
+ */
+export interface DataSourceOptions {
+  /**
+   * The name of the data source, overrides the id given by cdk
+   *
+   * @default - the id provisioned
+   */
+  readonly name?: string;
+
+  /**
+   * The description of the data source
+   *
+   * @default - No description
+   */
+  readonly description?: string;
+}
+
+/**
+ * Interface for GraphQL
+ */
+export interface IGraphqlApi extends IResource {
+
+  /**
+   * an unique AWS AppSync GraphQL API identifier
+   * i.e. 'lxz775lwdrgcndgz3nurvac7oa'
+   *
+   * @attribute
+   */
+  readonly apiId: string;
+
+  /**
+   * the ARN of the API
+   *
+   * @attribute
+   */
+  readonly arn: string;
+
+  /**
+   * add a new dummy data source to this API. Useful for pipeline resolvers
+   * and for backend changes that don't require a data source.
+   *
+   * @param id The data source's id
+   * @param options The optional configuration for this data source
+   * @default name - the id
+   * description - No description
+   */
+  addNoneDataSource(id: string, options?: DataSourceOptions): NoneDataSource;
+
+  /**
+   * add a new DynamoDB data source to this API
+   *
+   * @param id The data source's id
+   * @param table The DynamoDB table backing this data source
+   * @param options The optional configuration for this data source
+   * @default name - the id
+   * description - No description
+   */
+  addDynamoDbDataSource(id: string, table: ITable, options?: DataSourceOptions): DynamoDbDataSource;
+
+  /**
+   * add a new http data source to this API
+   *
+   * @param id The data source's id
+   * @param endpoint The http endpoint
+   * @param options The optional configuration for this data source
+   * @default name - 'the id
+   * description - No description
+   */
+  addHttpDataSource(id: string, endpoint: string, options?: DataSourceOptions): HttpDataSource;
+
+  /**
+   * add a new Lambda data source to this API
+   *
+   * @param id The data source's id
+   * @param lambdaFunction The Lambda function to call to interact with this data source
+   * @param options The optional configuration for this data source
+   * @default name - the id
+   * description - No description
+   */
+  addLambdaDataSource(id: string, lambdaFunction: IFunction, options?: DataSourceOptions): LambdaDataSource;
+
+  /**
+   * Add schema dependency if not imported
+   *
+   * @param construct the dependee
+   */
+  addSchemaDependency(construct: CfnResource): boolean;
+}
+
+/**
+ * Base Class for GraphQL API
+ */
+export abstract class GraphqlApiBase extends Resource implements IGraphqlApi {
+
+  /**
+   * an unique AWS AppSync GraphQL API identifier
+   * i.e. 'lxz775lwdrgcndgz3nurvac7oa'
+   */
+  public abstract readonly apiId: string;
+
+  /**
+   * the ARN of the API
+   */
+  public abstract readonly arn: string;
+
+  /**
+   * add a new dummy data source to this API. Useful for pipeline resolvers
+   * and for backend changes that don't require a data source.
+   *
+   * @param id The data source's id
+   * @param options The optional configuration for this data source
+   * @default name - the id
+   * description - No description
+   */
+  public addNoneDataSource(id: string, options?: DataSourceOptions): NoneDataSource {
+    return new NoneDataSource(this, id, {
+      api: this,
+      name: options?.name,
+      description: options?.description,
+    });
+  }
+
+  /**
+   * add a new DynamoDB data source to this API
+   *
+   * @param id The data source's id
+   * @param table The DynamoDB table backing this data source
+   * @param options The optional configuration for this data source
+   * @default name - the id
+   * description - No description
+   */
+  public addDynamoDbDataSource(id: string, table: ITable, options?: DataSourceOptions): DynamoDbDataSource {
+    return new DynamoDbDataSource(this, id, {
+      api: this,
+      table,
+      name: options?.name,
+      description: options?.description,
+    });
+  }
+
+  /**
+   * add a new http data source to this API
+   *
+   * @param id The data source's id
+   * @param endpoint The http endpoint
+   * @param options The optional configuration for this data source
+   * @default name - 'the id
+   * description - No description
+   */
+  public addHttpDataSource(id: string, endpoint: string, options?: DataSourceOptions): HttpDataSource {
+    return new HttpDataSource(this, id, {
+      api: this,
+      endpoint,
+      name: options?.name,
+      description: options?.description,
+    });
+  }
+
+  /**
+   * add a new Lambda data source to this API
+   *
+   * @param id The data source's id
+   * @param lambdaFunction The Lambda function to call to interact with this data source
+   * @param options The optional configuration for this data source
+   * @default name - the id
+   * description - No description
+   */
+  public addLambdaDataSource(id: string, lambdaFunction: IFunction, options?: DataSourceOptions): LambdaDataSource {
+    return new LambdaDataSource(this, id, {
+      api: this,
+      lambdaFunction,
+      name: options?.name,
+      description: options?.description,
+    });
+  }
+
+  /**
+   * Add schema dependency if not imported
+   *
+   * @param construct the dependee
+   */
+  public addSchemaDependency(construct: CfnResource): boolean {
+    construct;
+    return false;
+  }
+}