Assign a physical name to the S3 Bucket in CodePipeline if a customer…

… did not pass an explicit one and the Pipeline is cross-account.

packages/@aws-cdk/aws-codepipeline/lib/pipeline.ts

@@ -150,6 +150,7 @@ export class Pipeline extends cdk.Construct implements cpapi.IPipeline {
    */
   public readonly artifactBucket: s3.IBucket;
 
+  private readonly managedBucket: boolean;
   private readonly stages = new Array<Stage>();
   private eventsRole?: iam.Role;
   private readonly pipelineResource: CfnPipeline;
@@ -174,6 +175,9 @@ export class Pipeline extends cdk.Construct implements cpapi.IPipeline {
         encryptionKey,
         encryption: s3.BucketEncryption.Kms,
       });
+      this.managedBucket = true;
+    } else {
+      this.managedBucket = false;
     }
     this.artifactBucket = propsBucket;
 
@@ -416,6 +420,11 @@ export class Pipeline extends cdk.Construct implements cpapi.IPipeline {
         return action.role;
       }
 
+      // make sure the Bucket has a physical name if the Construct itself is managing it
+      if (this.managedBucket) {
+        this.artifactBucket.assignPhysicalNameIfNotSet();
+      }
+
       let actionRole = this.crossAccountActionRoles.get(resourceStack);
       if (!actionRole) {
         actionRole = new iam.Role(resourceStack, this.node.id + 'ActionRole', {

packages/@aws-cdk/aws-codepipeline/test/test.pipeline.ts

@@ -600,17 +600,15 @@ export = {
       const pipelineStack = new cdk.Stack(undefined, 'PipelineStack', {
         env: { account: '123456789012' },
       });
-      const bucketPhysicalName = 'artifact-bucket';
       const bucket = new s3.Bucket(pipelineStack, 'ArtifactBucket', {
-        bucketName: bucketPhysicalName,
+        bucketName: 'artifact-bucket',
         encryption: s3.BucketEncryption.Kms,
       });
       const sourceAction = bucket.toCodePipelineSourceAction({
         actionName: 'S3',
         bucketKey: 'path/to/file.zip',
       });
       new codepipeline.Pipeline(pipelineStack, 'Pipeline', {
-        artifactBucket: bucket,
         stages: [
           {
             name: 'Source',
@@ -684,7 +682,7 @@ export = {
                       {
                         "Ref": "AWS::Partition",
                       },
-                      `:s3:::${bucketPhysicalName}`,
+                      `:s3:::pipelinestack-artifactsbucket-5a14952fd11d`,
                     ],
                   ],
                 },
@@ -696,7 +694,7 @@ export = {
                       {
                         "Ref": "AWS::Partition",
                       },
-                      `:s3:::${bucketPhysicalName}/*`,
+                      `:s3:::pipelinestack-artifactsbucket-5a14952fd11d/*`,
                     ],
                   ],
                 },

packages/@aws-cdk/aws-s3/lib/bucket.ts

@@ -849,6 +849,10 @@ export class Bucket extends BucketBase {
     return this.onEvent(EventType.ObjectRemoved, dest, ...filters);
   }
 
+  public physicalNameGenerator(): cdk.PhysicalNameGenerator {
+    return super.physicalNameGenerator().toLowerCase();
+  }
+
   /**
    * Set up key properties and return the Bucket encryption property from the
    * user's configuration.

packages/@aws-cdk/cdk/lib/core/construct.ts

@@ -19,6 +19,8 @@ export interface IConstruct extends IDependable {
   readonly physicalName: string;
 
   readonly tryPhysicalName?: string
+
+  assignPhysicalNameIfNotSet(name?: string): boolean;
 }
 
 /**

packages/@aws-cdk/cdk/lib/util/physical-name-generator.ts

@@ -2,10 +2,6 @@ import crypto = require('crypto');
 import { Stack } from '../cloudformation/stack';
 import { IConstruct } from '../core/construct';
 
-// interface {
-//
-// }
-
 export class PhysicalNameGenerator {
   public static from(construct: IConstruct): PhysicalNameGenerator {
     return new PhysicalNameGenerator(
@@ -18,6 +14,7 @@ export class PhysicalNameGenerator {
   private readonly idPart: NamePart;
   private readonly stack: Stack;
   private readonly hashLength: number;
+  private changeToLowerCase = false;
 
   private constructor(stackPart: NamePart, idPart: NamePart, stack: Stack) {
     this.stackPart = stackPart;
@@ -38,9 +35,16 @@ export class PhysicalNameGenerator {
     const parts = [this.stackPart, this.idPart]
       .map(part => part.generate());
 
-    return [...parts, hash]
+    const ret = [...parts, hash]
       .filter(part => part.length > 0)
       .join('-');
+
+    return this.changeToLowerCase ? ret.toLowerCase() : ret;
+  }
+
+  public toLowerCase(): PhysicalNameGenerator {
+    this.changeToLowerCase = true;
+    return this;
   }
 }