fix(apigateway): permission error in lambda integration when function name is modified

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

@@ -134,6 +134,19 @@ export interface IntegrationProps {
   readonly options?: IntegrationOptions;
 }
 
+/**
+ * Result of binding an Integration to the Method
+ */
+export interface IntegrationConfig {
+  /**
+   * This value is included in computing the Deployment's fingerprint. When the fingerprint
+   * changes a new deployment is triggered.
+   * This property should carry a different value when the Deployment needs to be refreshed.
+   * @default - deployments are not triggered for any change of this integration.
+   */
+  readonly deploymentFingerprint?: string;
+}
+
 /**
  * Base class for backend integrations for an API Gateway method.
  *
@@ -156,7 +169,7 @@ export class Integration {
    * 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) {
+  public bind(_method: Method): IntegrationConfig | undefined {
     return;
   }
 }

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 +92,8 @@ export class AwsIntegration extends Integration {
     });
   }
 
-  public bind(method: Method) {
+  public bind(method: Method): IntegrationConfig | undefined {
     this.scope = method;
+    return;
   }
 }

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

@@ -1,7 +1,8 @@
 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 { Lazy, Token } from '@aws-cdk/core';
+import * as crypto from 'crypto';
+import { IntegrationConfig, IntegrationOptions } from '../integration';
 import { Method } from '../method';
 import { AwsIntegration } from './aws';
 
@@ -52,7 +53,7 @@ export class LambdaIntegration extends AwsIntegration {
     this.enableTest = options.allowTestInvoke === undefined ? true : false;
   }
 
-  public bind(method: Method) {
+  public bind(method: Method): IntegrationConfig | undefined {
     super.bind(method);
     const principal = new iam.ServicePrincipal('apigateway.amazonaws.com');
 
@@ -72,5 +73,16 @@ export class LambdaIntegration extends AwsIntegration {
         sourceArn: method.testMethodArn,
       });
     }
+
+    const cfnFunction = this.handler.node.defaultChild as lambda.CfnFunction;
+    let deploymentFingerprint;
+    if (!Token.isUnresolved(cfnFunction.functionName)) {
+      const md5 = crypto.createHash('md5');
+      md5.update(JSON.stringify({ functionName: cfnFunction.functionName }));
+      deploymentFingerprint = md5.digest('hex');
+    }
+    return {
+      deploymentFingerprint,
+    };
   }
 }

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

@@ -192,6 +192,9 @@ export class Method extends Resource {
       authorizer._attachToApi(this.api);
     }
 
+    const integration = props.integration ?? this.resource.defaultIntegration ?? new MockIntegration();
+    const bindResult = integration.bind(this);
+
     const methodProps: CfnMethodProps = {
       resourceId: props.resource.resourceId,
       restApiId: this.api.restApiId,
@@ -201,7 +204,7 @@ export class Method extends Resource {
       authorizationType,
       authorizerId,
       requestParameters: options.requestParameters || defaultMethodOptions.requestParameters,
-      integration: this.renderIntegration(props.integration),
+      integration: this.renderIntegration(integration),
       methodResponses: this.renderMethodResponses(options.methodResponses),
       requestModels: this.renderRequestModels(options.requestModels),
       requestValidatorId: this.requestValidatorId(options),
@@ -219,7 +222,12 @@ export class Method extends Resource {
     const deployment = props.resource.api.latestDeployment;
     if (deployment) {
       deployment.node.addDependency(resource);
-      deployment.addToLogicalId({ method: methodProps });
+      deployment.addToLogicalId({
+        method: {
+          ...methodProps,
+          integrationFingerprint: bindResult?.deploymentFingerprint,
+        },
+      });
     }
   }
 
@@ -255,19 +263,7 @@ export class Method extends Resource {
     return this.api.arnForExecuteApi(this.httpMethod, pathForArn(this.resource.path), 'test-invoke-stage');
   }
 
-  private renderIntegration(integration?: Integration): CfnMethod.IntegrationProperty {
-    if (!integration) {
-      // use defaultIntegration from API if defined
-      if (this.resource.defaultIntegration) {
-        return this.renderIntegration(this.resource.defaultIntegration);
-      }
-
-      // fallback to mock
-      return this.renderIntegration(new MockIntegration());
-    }
-
-    integration.bind(this);
-
+  private renderIntegration(integration: Integration): CfnMethod.IntegrationProperty {
     const options = integration._props.options || { };
 
     let credentials;

packages/@aws-cdk/aws-apigateway/test/integ.restapi.multistack.expected.json

@@ -120,7 +120,7 @@
           "BooksApi60AC975F"
         ]
       },
-      "BooksApiDeployment86CA39AF7e6c771d47a1a3777eba99bffc037822": {
+      "BooksApiDeployment86CA39AF56d02ab7284ced4885bcbbf29f6d01a6": {
         "Type": "AWS::ApiGateway::Deployment",
         "Properties": {
           "RestApiId": {
@@ -141,7 +141,7 @@
             "Ref": "BooksApi60AC975F"
           },
           "DeploymentId": {
-            "Ref": "BooksApiDeployment86CA39AF7e6c771d47a1a3777eba99bffc037822"
+            "Ref": "BooksApiDeployment86CA39AF56d02ab7284ced4885bcbbf29f6d01a6"
           },
           "StageName": "prod"
         }

packages/@aws-cdk/aws-apigateway/test/test.lambda.ts

@@ -215,4 +215,48 @@ export = {
 
     test.done();
   },
+
+  'fingerprint is computed when functionName is specified'(test: Test) {
+    // GIVEN
+    const stack = new cdk.Stack();
+    const restapi = new apigateway.RestApi(stack, 'RestApi');
+    const method = restapi.root.addMethod('ANY');
+    const handler = new lambda.Function(stack, 'MyFunc', {
+      functionName: 'ThisFunction',
+      runtime: lambda.Runtime.NODEJS_10_X,
+      handler: 'index.handler',
+      code: lambda.Code.fromInline('loo'),
+    });
+    const integration = new apigateway.LambdaIntegration(handler);
+
+    // WHEN
+    const bindResult = integration.bind(method);
+
+    // THEN
+    test.ok(bindResult?.deploymentFingerprint);
+    test.equals(bindResult!.deploymentFingerprint, '2092bc5e2b20cfce7e5eea5952f10c50');
+
+    test.done();
+  },
+
+  'fingerprint is not computed when functionName is not specified'(test: Test) {
+    // GIVEN
+    const stack = new cdk.Stack();
+    const restapi = new apigateway.RestApi(stack, 'RestApi');
+    const method = restapi.root.addMethod('ANY');
+    const handler = new lambda.Function(stack, 'MyFunc', {
+      runtime: lambda.Runtime.NODEJS_10_X,
+      handler: 'index.handler',
+      code: lambda.Code.fromInline('loo'),
+    });
+    const integration = new apigateway.LambdaIntegration(handler);
+
+    // WHEN
+    const bindResult = integration.bind(method);
+
+    // THEN
+    test.equals(bindResult?.deploymentFingerprint, undefined);
+
+    test.done();
+  },
 };