fix(codepipeline): cross-region support stack requires bootstrapping (#10217)

The cross-region support stack was intended to not require
bootstrapping. The recent "version check" feature added to the
default synthesizer did lead to bootstrapping being required (because
an SSM parameter needed to be provisioned in the target environment).

Make adding that check switchable and switch it off for the support
stack (which uses a `BootstraplessSynthesizer`).

Fixes #10215.


----

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

Author: rix0rrr

packages/@aws-cdk/core/lib/stack-synthesizers/bootstrapless-synthesizer.ts

@@ -35,6 +35,7 @@ export class BootstraplessSynthesizer extends DefaultStackSynthesizer {
     super({
       deployRoleArn: props.deployRoleArn,
       cloudFormationExecutionRole: props.cloudFormationExecutionRoleArn,
+      generateBootstrapVersionRule: false,
     });
   }
 

packages/@aws-cdk/core/lib/stack-synthesizers/default-synthesizer.ts

@@ -140,6 +140,16 @@ export interface DefaultStackSynthesizerProps {
    * @default - Value of context key '@aws-cdk/core:bootstrapQualifier' if set, otherwise `DefaultStackSynthesizer.DEFAULT_QUALIFIER`
    */
   readonly qualifier?: string;
+
+  /**
+   * Whether to add a Rule to the stack template verifying the bootstrap stack version
+   *
+   * This generally should be left set to `true`, unless you explicitly
+   * want to be able to deploy to an unbootstrapped environment.
+   *
+   * @default true
+   */
+  readonly generateBootstrapVersionRule?: boolean;
 }
 
 /**
@@ -235,7 +245,9 @@ export class DefaultStackSynthesizer implements IStackSynthesizer {
     this.imageAssetPublishingRoleArn = specialize(this.props.imageAssetPublishingRoleArn ?? DefaultStackSynthesizer.DEFAULT_IMAGE_ASSET_PUBLISHING_ROLE_ARN);
     /* eslint-enable max-len */
 
-    addBootstrapVersionRule(stack, MIN_BOOTSTRAP_STACK_VERSION, qualifier);
+    if (this.props.generateBootstrapVersionRule ?? true) {
+      addBootstrapVersionRule(stack, MIN_BOOTSTRAP_STACK_VERSION, qualifier);
+    }
   }
 
   public addFileAsset(asset: FileAssetSource): FileAssetLocation {

packages/@aws-cdk/core/test/stack-synthesis/test.new-style-synthesis.ts

@@ -83,6 +83,24 @@ export = {
     test.done();
   },
 
+  'version check is not added to template if disabled'(test: Test) {
+    // GIVEN
+    stack = new Stack(app, 'Stack2', {
+      synthesizer: new DefaultStackSynthesizer({
+        generateBootstrapVersionRule: false,
+      }),
+    });
+    new CfnResource(stack, 'Resource', {
+      type: 'Some::Resource',
+    });
+
+    // THEN
+    const template = app.synth().getStackByName('Stack2').template;
+    test.equal(template?.Rules?.CheckBootstrapVersion, undefined);
+
+    test.done();
+  },
+
   'add file asset'(test: Test) {
     // WHEN
     const location = stack.synthesizer.addFileAsset({