feat(core): generalization of dependencies (#1583)

Constructs can now take a dependency on any other construct.

Before, only `Resource`s could take dependencies, and they would depend
on `IDependable` which had to be implemented explicitly. In this change
we generalize the concept of dependencies from construct trees to other
construct trees; all constructs now take dependencies and also implement
`IDependable`.  The semantics are that any resource in the depending
tree will depend on all resources in the depended tree.

Dependencies are cross-stack aware

If you take a dependency on a construct in another stack, the dependency
does not get rendered in the template, but is instead added as a
dependency between stacks.

Fixes #1568, fixes #95.

BREAKING CHANGE: `resource.addDependency()` has been moved onto
`ConstructNode`. You now write `resource.node.addDependency()`. VPC's
`internetDependency` has been moved to the subnets as
`internetConnectivityEstablished`. Target Group's
`loadBalancerAssociationDependencies` has been renamed to
`loadBalancerAttached`.

Author: rix0rrr

examples/cdk-examples-typescript/custom-resource/index.ts

@@ -16,8 +16,7 @@ interface DemoResourceProps {
   failCreate?: boolean;
 }
 
-class DemoResource extends cdk.Construct implements cdk.IDependable {
-  public readonly dependencyElements: cdk.IDependable[];
+class DemoResource extends cdk.Construct {
   public readonly response: string;
 
   constructor(scope: cdk.Construct, id: string, props: DemoResourceProps) {
@@ -36,7 +35,6 @@ class DemoResource extends cdk.Construct implements cdk.IDependable {
     });
 
     this.response = resource.getAtt('Response').toString();
-    this.dependencyElements = [resource];
   }
 }
 
@@ -91,7 +89,7 @@ class FailAfterCreatingStack extends cdk.Stack {
     });
 
     // Make sure the rollback gets triggered only after the custom resource has been fully created.
-    bucket.addDependency(resource);
+    bucket.node.addDependency(resource);
   }
 }
 

examples/cdk-examples-typescript/resource-overrides/index.ts

@@ -31,7 +31,7 @@ class ResourceOverridesExample extends cdk.Stack {
         // This is how to specify resource options such as dependencies, metadata, update policy
         //
 
-        bucketResource.addDependency(otherBucket.node.findChild('Resource') as cdk.Resource);
+        bucketResource.node.addDependency(otherBucket.node.findChild('Resource') as cdk.Resource);
         bucketResource.options.metadata = { MetadataKey: 'MetadataValue' };
         bucketResource.options.updatePolicy = {
             autoScalingRollingUpdate: {

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

@@ -51,18 +51,13 @@ export interface DeploymentProps  {
  * Furthermore, since a deployment does not reference any of the REST API
  * resources and methods, CloudFormation will likely provision it before these
  * resources are created, which means that it will represent a "half-baked"
- * model. Use the `addDependency(dep)` method to circumvent that. This is done
+ * model. Use the `node.addDependency(dep)` method to circumvent that. This is done
  * automatically for the `restApi.latestDeployment` deployment.
  */
-export class Deployment extends cdk.Construct implements cdk.IDependable {
+export class Deployment extends cdk.Construct {
   public readonly deploymentId: string;
   public readonly api: IRestApi;
 
-  /**
-   * Allows taking a dependency on this construct.
-   */
-  public readonly dependencyElements = new Array<cdk.IDependable>();
-
   private readonly resource: LatestDeploymentResource;
 
   constructor(scope: cdk.Construct, id: string, props: DeploymentProps) {
@@ -79,15 +74,6 @@ export class Deployment extends cdk.Construct implements cdk.IDependable {
 
     this.api = props.api;
     this.deploymentId = new cdk.Token(() => this.resource.deploymentId).toString();
-    this.dependencyElements.push(this.resource);
-  }
-
-  /**
-   * Adds a dependency for this deployment. Should be called by all resources and methods
-   * so they are provisioned before this Deployment.
-   */
-  public addDependency(dep: cdk.IDependable) {
-    this.resource.addDependency(dep);
   }
 
   /**
@@ -182,5 +168,7 @@ class LatestDeploymentResource extends CfnDeployment {
 
       this.lazyLogicalId = this.originalLogicalId + md5.digest("hex");
     }
+
+    super.prepare();
   }
 }

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

@@ -104,7 +104,7 @@ export class Method extends cdk.Construct {
 
     const deployment = props.resource.resourceApi.latestDeployment;
     if (deployment) {
-      deployment.addDependency(resource);
+      deployment.node.addDependency(resource);
       deployment.addToLogicalId({ method: methodProps });
     }
   }

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

@@ -118,7 +118,7 @@ export class Resource extends cdk.Construct implements IRestApiResource {
 
     const deployment = props.parent.resourceApi.latestDeployment;
     if (deployment) {
-      deployment.addDependency(resource);
+      deployment.node.addDependency(resource);
       deployment.addToLogicalId({ resource: resourceProps });
     }
 

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

@@ -154,7 +154,7 @@ export interface RestApiProps extends ResourceOptions {
  * By default, the API will automatically be deployed and accessible from a
  * public endpoint.
  */
-export class RestApi extends cdk.Construct implements cdk.IDependable, IRestApi {
+export class RestApi extends cdk.Construct implements IRestApi {
   /**
    * Imports an existing REST API resource.
    * @param parent Parent construct
@@ -177,11 +177,6 @@ export class RestApi extends cdk.Construct implements cdk.IDependable, IRestApi
    */
   public latestDeployment?: Deployment;
 
-  /**
-   * Allows taking a dependency on this construct.
-   */
-  public readonly dependencyElements = new Array<cdk.IDependable>();
-
   /**
    * API Gateway stage that points to the latest deployment (if defined).
    *
@@ -226,16 +221,9 @@ export class RestApi extends cdk.Construct implements cdk.IDependable, IRestApi
       this.configureCloudWatchRole(resource);
     }
 
-    this.dependencyElements.push(resource);
-    if (this.latestDeployment) {
-      this.dependencyElements.push(this.latestDeployment);
-    }
-    if (this.deploymentStage) {
-      this.dependencyElements.push(this.deploymentStage);
-    }
-
     // configure the "root" resource
     this.root = {
+      get dependencyRoots() { return [this]; },
       node: this.node,
       addResource: (pathPart: string, options?: ResourceOptions) => {
         return new Resource(this, pathPart, { parent: this.root, pathPart, ...options });
@@ -372,7 +360,7 @@ export class RestApi extends cdk.Construct implements cdk.IDependable, IRestApi
       cloudWatchRoleArn: role.roleArn
     });
 
-    resource.addDependency(apiResource);
+    resource.node.addDependency(apiResource);
   }
 }
 

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

@@ -133,9 +133,8 @@ export interface MethodDeploymentOptions {
   cacheDataEncrypted?: boolean;
 }
 
-export class Stage extends cdk.Construct implements cdk.IDependable {
+export class Stage extends cdk.Construct {
   public readonly stageName: string;
-  public readonly dependencyElements = new Array<cdk.IDependable>();
 
   private readonly restApi: IRestApi;
 
@@ -170,7 +169,6 @@ export class Stage extends cdk.Construct implements cdk.IDependable {
 
     this.stageName = resource.ref;
     this.restApi = props.deployment.api;
-    this.dependencyElements.push(resource);
   }
 
   /**

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

@@ -530,8 +530,8 @@
         "booksapibooksGETA776447A",
         "booksapibooksPOSTF6C6559D",
         "booksapibooksbookid5264BCA2",
-        "booksapibooksbookidGETCCE21986",
-        "booksapibooksbookidDELETE214F4059"
+        "booksapibooksbookidDELETE214F4059",
+        "booksapibooksbookidGETCCE21986"
       ]
     },
     "booksapiDeploymentStageprod55D8E03E": {
@@ -837,7 +837,9 @@
               "Ref": "AWS::Region"
             },
             ".",
-            { "Ref": "AWS::URLSuffix" },
+            {
+              "Ref": "AWS::URLSuffix"
+            },
             "/",
             {
               "Ref": "booksapiDeploymentStageprod55D8E03E"

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

@@ -110,7 +110,9 @@
               "Ref": "AWS::Region"
             },
             ".",
-            { "Ref": "AWS::URLSuffix" },
+            {
+              "Ref": "AWS::URLSuffix"
+            },
             "/",
             {
               "Ref": "myapiDeploymentStageprod298F01AF"

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

@@ -16,15 +16,15 @@
       },
       "DependsOn": [
         "myapiv113487378",
-        "myapiv1toysA55FCBC4",
-        "myapiv1toysGET7348114D",
-        "myapiv1toysPOST55128058",
-        "myapiv1toysPUT59AFBBC2",
         "myapiv1appliances507FEFF4",
         "myapiv1appliancesGET8FE872EC",
         "myapiv1books1D4BE6C1",
         "myapiv1booksGETC6B996D0",
-        "myapiv1booksPOST53E2832E"
+        "myapiv1booksPOST53E2832E",
+        "myapiv1toysA55FCBC4",
+        "myapiv1toysGET7348114D",
+        "myapiv1toysPOST55128058",
+        "myapiv1toysPUT59AFBBC2"
       ],
       "DeletionPolicy": "Retain"
     },
@@ -602,7 +602,9 @@
               "Ref": "AWS::Region"
             },
             ".",
-            { "Ref": "AWS::URLSuffix" },
+            {
+              "Ref": "AWS::URLSuffix"
+            },
             "/",
             {
               "Ref": "myapiDeploymentStagebeta96434BEB"