fix(codepipeline-actions): use token as CodeCommitSourceAction branch (…

…#10463)

When using the EVENTS trigger, an event is created based on the branch name of 
the event, however this is not possible if the branch name is an unresolved
value. Therefore generate a unique event name if this is the case.

Fixes #10263

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/aws-codepipeline-actions/lib/codecommit/source-action.ts

@@ -2,7 +2,7 @@ import * as codecommit from '@aws-cdk/aws-codecommit';
 import * as codepipeline from '@aws-cdk/aws-codepipeline';
 import * as targets from '@aws-cdk/aws-events-targets';
 import * as iam from '@aws-cdk/aws-iam';
-import { Construct } from '@aws-cdk/core';
+import { Construct, Token } from '@aws-cdk/core';
 import { Action } from '../action';
 import { sourceArtifactBounds } from '../common';
 
@@ -122,8 +122,8 @@ export class CodeCommitSourceAction extends Action {
     const createEvent = this.props.trigger === undefined ||
       this.props.trigger === CodeCommitTrigger.EVENTS;
     if (createEvent) {
-      const branchIdDisambiguator = this.branch === 'master' ? '' : `-${this.branch}-`;
-      this.props.repository.onCommit(`${stage.pipeline.node.uniqueId}${branchIdDisambiguator}EventRule`, {
+      const eventId = this.generateEventId(stage);
+      this.props.repository.onCommit(eventId, {
         target: new targets.CodePipeline(stage.pipeline),
         branches: [this.branch],
       });
@@ -153,4 +153,24 @@ export class CodeCommitSourceAction extends Action {
       },
     };
   }
+
+  private generateEventId(stage: codepipeline.IStage): string {
+    const baseId = stage.pipeline.node.uniqueId;
+    if (Token.isUnresolved(this.branch)) {
+      let candidate = '';
+      let counter = 0;
+      do {
+        candidate = this.eventIdFromPrefix(`${baseId}${counter}`);
+        counter += 1;
+      } while (this.props.repository.node.tryFindChild(candidate) !== undefined);
+      return candidate;
+    } else {
+      const branchIdDisambiguator = this.branch === 'master' ? '' : '-${this.branch}-';
+      return this.eventIdFromPrefix(`${baseId}${branchIdDisambiguator}`);
+    }
+  }
+
+  private eventIdFromPrefix(eventIdPrefix: string) {
+    return `${eventIdPrefix}EventRule`;
+  }
 }

packages/@aws-cdk/aws-codepipeline-actions/test/codecommit/test.codecommit-source-action.ts

@@ -2,7 +2,7 @@ import { countResources, expect, haveResourceLike, not } from '@aws-cdk/assert';
 import * as codebuild from '@aws-cdk/aws-codebuild';
 import * as codecommit from '@aws-cdk/aws-codecommit';
 import * as codepipeline from '@aws-cdk/aws-codepipeline';
-import { Stack } from '@aws-cdk/core';
+import { Stack, Lazy } from '@aws-cdk/core';
 import { Test } from 'nodeunit';
 import * as cpactions from '../../lib';
 
@@ -224,6 +224,49 @@ export = {
 
       test.done();
     },
+
+    'allows using a Token for the branch name'(test: Test) {
+      const stack = new Stack();
+
+      const sourceOutput = new codepipeline.Artifact();
+      new codepipeline.Pipeline(stack, 'P', {
+        stages: [
+          {
+            stageName: 'Source',
+            actions: [
+              new cpactions.CodeCommitSourceAction({
+                actionName: 'CodeCommit',
+                repository: new codecommit.Repository(stack, 'R', {
+                  repositoryName: 'repository',
+                }),
+                branch: Lazy.stringValue({ produce: () => 'my-branch' }),
+                output: sourceOutput,
+              }),
+            ],
+          },
+          {
+            stageName: 'Build',
+            actions: [
+              new cpactions.CodeBuildAction({
+                actionName: 'Build',
+                project: new codebuild.PipelineProject(stack, 'CodeBuild'),
+                input: sourceOutput,
+              }),
+            ],
+          },
+        ],
+      });
+
+      expect(stack).to(haveResourceLike('AWS::Events::Rule', {
+        EventPattern: {
+          detail: {
+            referenceName: ['my-branch'],
+          },
+        },
+      }));
+
+      test.done();
+    },
   },
 };