From 549ad732a7df9540acdb1dd5a8494e1806d7b11e Mon Sep 17 00:00:00 2001
From: Tomas Mazak <tomas@valec.net>
Date: Tue, 22 Sep 2020 00:54:14 +0200
Subject: [PATCH] feat(pipelines): add a property to CdkPipeline to allow
 disabling self-mutation

---
 packages/@aws-cdk/pipelines/README.md         | 18 ++++++++++
 packages/@aws-cdk/pipelines/lib/pipeline.ts   | 34 ++++++++++++++-----
 .../@aws-cdk/pipelines/test/pipeline.test.ts  | 28 ++++++++++++++-
 3 files changed, 70 insertions(+), 10 deletions(-)

diff --git a/packages/@aws-cdk/pipelines/README.md b/packages/@aws-cdk/pipelines/README.md
index d567675f1ca2f..e975a7502b720 100644
--- a/packages/@aws-cdk/pipelines/README.md
+++ b/packages/@aws-cdk/pipelines/README.md
@@ -543,6 +543,24 @@ class MyPipelineStack extends Stack {
 }
 ```
 
+### Developing the pipeline
+
+The self-mutation feature of the `CdkPipeline` might at times get in the way
+of the pipeline development workflow. Each change to the pipeline must be pushed
+to git, otherwise, after the pipeline was updated using `cdk deploy`, it will
+automatically revert to the state found in git.
+
+To make the development more convenient, the self-mutation feature can be turned
+off temporarily, by passing `selfMutating: false` property, example:
+
+```ts
+const pipeline = new CdkPipeline(this, 'Pipeline', {
+  selfMutating: false,
+  ...  
+});
+```
+
+
 ## CDK Environment Bootstrapping
 
 An *environment* is an *(account, region)* pair where you want to deploy a
diff --git a/packages/@aws-cdk/pipelines/lib/pipeline.ts b/packages/@aws-cdk/pipelines/lib/pipeline.ts
index 28358928ecc35..0233af8ed87ca 100644
--- a/packages/@aws-cdk/pipelines/lib/pipeline.ts
+++ b/packages/@aws-cdk/pipelines/lib/pipeline.ts
@@ -105,6 +105,20 @@ export interface CdkPipelineProps {
    * @default - All private subnets.
    */
   readonly subnetSelection?: ec2.SubnetSelection;
+
+  /**
+   * Whether the pipeline will update itself
+   *
+   * This needs to be set to `true` to allow the pipeline to reconfigure
+   * itself when assets or stages are being added to it, and `true` is the
+   * recommended setting.
+   *
+   * You can temporarily set this to `false` while you are iterating
+   * on the pipeline itself and prefer to deploy changes using `cdk deploy`.
+   *
+   * @default true
+   */
+  readonly selfMutating?: boolean;
 }
 
 /**
@@ -178,15 +192,17 @@ export class CdkPipeline extends CoreConstruct {
       });
     }
 
-    this._pipeline.addStage({
-      stageName: 'UpdatePipeline',
-      actions: [new UpdatePipelineAction(this, 'UpdatePipeline', {
-        cloudAssemblyInput: this._cloudAssemblyArtifact,
-        pipelineStackName: pipelineStack.stackName,
-        cdkCliVersion: props.cdkCliVersion,
-        projectName: maybeSuffix(props.pipelineName, '-selfupdate'),
-      })],
-    });
+    if (props.selfMutating ?? true) {
+      this._pipeline.addStage({
+        stageName: 'UpdatePipeline',
+        actions: [new UpdatePipelineAction(this, 'UpdatePipeline', {
+          cloudAssemblyInput: this._cloudAssemblyArtifact,
+          pipelineStackName: pipelineStack.stackName,
+          cdkCliVersion: props.cdkCliVersion,
+          projectName: maybeSuffix(props.pipelineName, '-selfupdate'),
+        })],
+      });
+    }
 
     this._assets = new AssetPublishing(this, 'Assets', {
       cloudAssemblyInput: this._cloudAssemblyArtifact,
diff --git a/packages/@aws-cdk/pipelines/test/pipeline.test.ts b/packages/@aws-cdk/pipelines/test/pipeline.test.ts
index 023f4bdcf575d..003aacf021d47 100644
--- a/packages/@aws-cdk/pipelines/test/pipeline.test.ts
+++ b/packages/@aws-cdk/pipelines/test/pipeline.test.ts
@@ -1,6 +1,15 @@
 import * as fs from 'fs';
 import * as path from 'path';
-import { anything, arrayWith, Capture, deepObjectLike, encodedJson, objectLike, stringLike } from '@aws-cdk/assert';
+import {
+  anything,
+  arrayWith,
+  Capture,
+  deepObjectLike,
+  encodedJson,
+  notMatching,
+  objectLike,
+  stringLike,
+} from '@aws-cdk/assert';
 import '@aws-cdk/assert/jest';
 import * as cp from '@aws-cdk/aws-codepipeline';
 import * as cpa from '@aws-cdk/aws-codepipeline-actions';
@@ -332,6 +341,23 @@ test('selfmutation stage correctly identifies nested assembly of pipeline stack'
   });
 });
 
+test('selfmutation feature can be turned off', () => {
+  const stack = new Stack();
+  const cloudAssemblyArtifact = new cp.Artifact();
+  // WHEN
+  new TestGitHubNpmPipeline(stack, 'Cdk', {
+    cloudAssemblyArtifact,
+    selfMutating: false,
+  });
+  // THEN
+  expect(stack).toHaveResourceLike('AWS::CodePipeline::Pipeline', {
+    Stages: notMatching(arrayWith({
+      Name: 'UpdatePipeline',
+      Actions: anything(),
+    })),
+  });
+});
+
 test('overridden stack names are respected', () => {
   // WHEN
   pipeline.addApplicationStage(new OneStackAppWithCustomName(app, 'App1'));