feat(aws-cloudformation): allow specifying custom resource type (#943)

Adds the `resourceType` property to `CustomResource`
which allows specifying the type name for the resource.

Custom resource type names must start with "Custom::" and
have some naming restrictions, which are validated.

Author: Elad Ben-Israel

packages/@aws-cdk/aws-cloudformation/lib/custom-resource.ts

@@ -32,6 +32,27 @@ export interface CustomResourceProps {
    * Properties to pass to the Lambda
    */
   properties?: Properties;
+
+  /**
+   * For custom resources, you can specify AWS::CloudFormation::CustomResource
+   * (the default) as the resource type, or you can specify your own resource
+   * type name. For example, you can use "Custom::MyCustomResourceTypeName".
+   *
+   * Custom resource type names must begin with "Custom::" and can include
+   * alphanumeric characters and the following characters: _@-. You can specify
+   * a custom resource type name up to a maximum length of 60 characters. You
+   * cannot change the type during an update.
+   *
+   * Using your own resource type names helps you quickly differentiate the
+   * types of custom resources in your stack. For example, if you had two custom
+   * resources that conduct two different ping tests, you could name their type
+   * as Custom::PingTester to make them easily identifiable as ping testers
+   * (instead of using AWS::CloudFormation::CustomResource).
+   *
+   * @see
+   * https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-cfn-customresource.html#aws-cfn-resource-type-name
+   */
+  resourceType?: string;
 }
 
 /**
@@ -57,6 +78,10 @@ export class CustomResource extends cloudformation.CustomResource {
     });
 
     this.userProperties = props.properties;
+
+    if (props.resourceType) {
+      this.useCustomResourceType(props.resourceType);
+    }
   }
 
   /**
@@ -67,6 +92,23 @@ export class CustomResource extends cloudformation.CustomResource {
     return Object.assign(props, uppercaseProperties(this.userProperties || {}));
   }
 
+  private useCustomResourceType(resourceType: string) {
+    if (!resourceType.startsWith('Custom::')) {
+      throw new Error(`Custom resource type must begin with "Custom::" (${resourceType})`);
+    }
+
+    const typeName = resourceType.substr(resourceType.indexOf('::') + 2);
+    if (typeName.length > 60) {
+      throw new Error(`Custom resource type length > 60 (${resourceType})`);
+    }
+
+    if (!/^[a-z0-9_@-]+$/i.test(typeName)) {
+      throw new Error(`Custom resource type name can only include alphanumeric characters and _@- (${typeName})`);
+    }
+
+    this.addOverride('Type', resourceType);
+  }
+
 }
 
 /**

packages/@aws-cdk/aws-cloudformation/test/test.resource.ts

@@ -1,5 +1,6 @@
-import { expect } from '@aws-cdk/assert';
+import { expect, haveResource } from '@aws-cdk/assert';
 import lambda = require('@aws-cdk/aws-lambda');
+import sns = require('@aws-cdk/aws-sns');
 import cdk = require('@aws-cdk/cdk');
 import { Test } from 'nodeunit';
 import { CustomResource } from '../lib';
@@ -85,7 +86,59 @@ export = {
       }
     });
     test.done();
-  }
+  },
+
+  'custom resources can specify a resource type that starts with Custom::'(test: Test) {
+    const stack = new cdk.Stack();
+    new CustomResource(stack, 'MyCustomResource', {
+      resourceType: 'Custom::MyCustomResourceType',
+      topicProvider: new sns.Topic(stack, 'Provider')
+    });
+    expect(stack).to(haveResource('Custom::MyCustomResourceType'));
+    test.done();
+  },
+
+  'fails if custom resource type is invalid': {
+    'does not start with "Custom::"'(test: Test) {
+      const stack = new cdk.Stack();
+
+      test.throws(() => {
+        new CustomResource(stack, 'MyCustomResource', {
+          resourceType: 'NoCustom::MyCustomResourceType',
+          topicProvider: new sns.Topic(stack, 'Provider')
+        });
+      }, /Custom resource type must begin with "Custom::"/);
+
+      test.done();
+    },
+
+    'has invalid characters'(test: Test) {
+      const stack = new cdk.Stack();
+
+      test.throws(() => {
+        new CustomResource(stack, 'MyCustomResource', {
+          resourceType: 'Custom::My Custom?ResourceType',
+          topicProvider: new sns.Topic(stack, 'Provider')
+        });
+      }, /Custom resource type name can only include alphanumeric characters and/);
+
+      test.done();
+    },
+
+    'is longer than 60 characters'(test: Test) {
+      const stack = new cdk.Stack();
+
+      test.throws(() => {
+        new CustomResource(stack, 'MyCustomResource', {
+          resourceType: 'Custom::0123456789012345678901234567890123456789012345678901234567891',
+          topicProvider: new sns.Topic(stack, 'Provider')
+        });
+      }, /Custom resource type length > 60/);
+
+      test.done();
+    },
+
+  },
 };
 
 class TestCustomResource extends cdk.Construct {