chore(apigateway): modernize Integration.bind()

Currently, the Method construct reaches into the internals of the
Integration class to construct itself, via the _props() internal method.

Change to a more recent pattern where the bind() returns a result that
contains all of the information that the Method class requires to
finalize the bind.

Motivation for the change
This change - #8813 - requires a
property returned to the Method that is not user specified. The change
already introduces this pattern. This PR takes it a bit further and
applies the same logic to existing properties, so that there is now only
one way for the Method to get the result of the bind.

packages/@aws-cdk/aws-apigateway/lib/integration.ts

@@ -134,30 +134,68 @@ export interface IntegrationProps {
   readonly options?: IntegrationOptions;
 }
 
+/**
+ * Result of binding an Integration to the Method.
+ */
+export interface IntegrationConfig {
+  /**
+   * Integration options.
+   * @default - no integration options
+   */
+  readonly options?: IntegrationOptions;
+
+  /**
+   * Specifies an API method integration type.
+   */
+  readonly type: IntegrationType;
+
+  /**
+   * The Uniform Resource Identifier (URI) for the integration.
+   * @see https://docs.aws.amazon.com/apigateway/api-reference/resource/integration/#uri
+   * @default - no URI. Usually applies to MOCK integration
+   */
+  readonly uri?: string;
+
+  /**
+   * The integration's HTTP method type.
+   * @default - no integration method specified.
+   */
+  readonly integrationHttpMethod?: string;
+}
+
 /**
  * Base class for backend integrations for an API Gateway method.
  *
  * Use one of the concrete classes such as `MockIntegration`, `AwsIntegration`, `LambdaIntegration`
  * or implement on your own by specifying the set of props.
  */
 export class Integration {
-  constructor(private readonly props: IntegrationProps) { }
-
-  /**
-   * Allows `Method` to access the integration props.
-   *
-   * @internal
-   */
-  public get _props() {
-    return this.props;
+  constructor(private readonly props: IntegrationProps) {
+    const options = this.props.options || { };
+    if (options.credentialsPassthrough !== undefined && options.credentialsRole !== undefined) {
+      throw new Error('\'credentialsPassthrough\' and \'credentialsRole\' are mutually exclusive');
+    }
+
+    if (options.connectionType === ConnectionType.VPC_LINK && options.vpcLink === undefined) {
+      throw new Error('\'connectionType\' of VPC_LINK requires \'vpcLink\' prop to be set');
+    }
+
+    if (options.connectionType === ConnectionType.INTERNET && options.vpcLink !== undefined) {
+      throw new Error('cannot set \'vpcLink\' where \'connectionType\' is INTERNET');
+    }
   }
 
   /**
    * Can be overridden by subclasses to allow the integration to interact with the method
    * being integrated, access the REST API object, method ARNs, etc.
    */
-  public bind(_method: Method) {
-    return;
+  public bind(_method: Method): IntegrationConfig {
+    return {
+      options: this.props.options,
+      type: this.props.type,
+      uri: this.props.uri,
+      integrationHttpMethod: this.props.integrationHttpMethod,
+    };
   }
 }
 

packages/@aws-cdk/aws-apigateway/lib/integrations/aws.ts

@@ -1,5 +1,5 @@
 import * as cdk from '@aws-cdk/core';
-import { Integration, IntegrationOptions, IntegrationType } from '../integration';
+import { Integration, IntegrationConfig, IntegrationOptions, IntegrationType } from '../integration';
 import { Method } from '../method';
 import { parseAwsApiCall } from '../util';
 
@@ -92,7 +92,9 @@ export class AwsIntegration extends Integration {
     });
   }
 
-  public bind(method: Method) {
+  public bind(method: Method): IntegrationConfig {
+    const bindResult = super.bind(method);
     this.scope = method;
+    return bindResult;
   }
 }

packages/@aws-cdk/aws-apigateway/lib/integrations/lambda.ts

@@ -1,7 +1,7 @@
 import * as iam from '@aws-cdk/aws-iam';
 import * as lambda from '@aws-cdk/aws-lambda';
 import { Lazy } from '@aws-cdk/core';
-import { IntegrationOptions } from '../integration';
+import { IntegrationConfig, IntegrationOptions } from '../integration';
 import { Method } from '../method';
 import { AwsIntegration } from './aws';
 
@@ -52,8 +52,8 @@ export class LambdaIntegration extends AwsIntegration {
     this.enableTest = options.allowTestInvoke === undefined ? true : false;
   }
 
-  public bind(method: Method) {
-    super.bind(method);
+  public bind(method: Method): IntegrationConfig {
+    const bindResult = super.bind(method);
     const principal = new iam.ServicePrincipal('apigateway.amazonaws.com');
 
     const desc = `${method.api.node.uniqueId}.${method.httpMethod}.${method.resource.path.replace(/\//g, '.')}`;
@@ -72,5 +72,6 @@ export class LambdaIntegration extends AwsIntegration {
         sourceArn: method.testMethodArn,
       });
     }
+    return bindResult;
   }
 }

packages/@aws-cdk/aws-apigateway/lib/method.ts

@@ -1,7 +1,7 @@
 import { Construct, Resource, Stack } from '@aws-cdk/core';
 import { CfnMethod, CfnMethodProps } from './apigateway.generated';
 import { Authorizer, IAuthorizer } from './authorizer';
-import { ConnectionType, Integration } from './integration';
+import { Integration } from './integration';
 import { MockIntegration } from './integrations/mock';
 import { MethodResponse } from './methodresponse';
 import { IModel } from './model';
@@ -266,23 +266,10 @@ export class Method extends Resource {
       return this.renderIntegration(new MockIntegration());
     }
 
-    integration.bind(this);
-
-    const options = integration._props.options || { };
+    const bindResult = integration.bind(this);
+    const options = bindResult.options || { };
 
     let credentials;
-    if (options.credentialsPassthrough !== undefined && options.credentialsRole !== undefined) {
-      throw new Error('\'credentialsPassthrough\' and \'credentialsRole\' are mutually exclusive');
-    }
-
-    if (options.connectionType === ConnectionType.VPC_LINK && options.vpcLink === undefined) {
-      throw new Error('\'connectionType\' of VPC_LINK requires \'vpcLink\' prop to be set');
-    }
-
-    if (options.connectionType === ConnectionType.INTERNET && options.vpcLink !== undefined) {
-      throw new Error('cannot set \'vpcLink\' where \'connectionType\' is INTERNET');
-    }
-
     if (options.credentialsRole) {
       credentials = options.credentialsRole.roleArn;
     } else if (options.credentialsPassthrough) {
@@ -292,12 +279,12 @@ export class Method extends Resource {
     }
 
     return {
-      type: integration._props.type,
-      uri: integration._props.uri,
+      type: bindResult.type,
+      uri: bindResult.uri,
       cacheKeyParameters: options.cacheKeyParameters,
       cacheNamespace: options.cacheNamespace,
       contentHandling: options.contentHandling,
-      integrationHttpMethod: integration._props.integrationHttpMethod,
+      integrationHttpMethod: bindResult.integrationHttpMethod,
       requestParameters: options.requestParameters,
       requestTemplates: options.requestTemplates,
       passthroughBehavior: options.passthroughBehavior,