fix(core): cdk diff on large templates fails when passing in toolkitStackName and qualifier

packages/@aws-cdk-testing/cli-integ/lib/with-cdk-app.ts

@@ -273,6 +273,11 @@ interface CommonCdkBootstrapCommandOptions {
    * @default - none
    */
   readonly tags?: string;
+
+  /**
+   * @default - the default CDK qualifier
+   */
+  readonly qualifier?: string;
 }
 
 export interface CdkLegacyBootstrapCommandOptions extends CommonCdkBootstrapCommandOptions {
@@ -423,7 +428,7 @@ export class TestFixture extends ShellHelper {
     if (options.bootstrapBucketName) {
       args.push('--bootstrap-bucket-name', options.bootstrapBucketName);
     }
-    args.push('--qualifier', this.qualifier);
+    args.push('--qualifier', options.qualifier ?? this.qualifier);
     if (options.cfnExecutionPolicy) {
       args.push('--cloudformation-execution-policies', options.cfnExecutionPolicy);
     }

packages/@aws-cdk-testing/cli-integ/tests/cli-integ-tests/cli.integtest.ts

@@ -1056,6 +1056,48 @@ integTest(
   }),
 );
 
+integTest('cdk diff with large changeset and custom toolkit stack name and qualifier does not fail', withoutBootstrap(async (fixture) => {
+  // Bootstrapping with custom toolkit stack name and qualifier
+  const qualifier = 'abc1234';
+  const toolkitStackName = 'custom-stack';
+  const bootstrapBucketName = 'cdk-abc1234-assets-587443617500-us-east-1';
+  await fixture.cdkBootstrapModern({
+    verbose: true,
+    toolkitStackName: toolkitStackName,
+    qualifier: qualifier,
+    bootstrapBucketName: bootstrapBucketName,
+  });
+
+  // Deploying small initial stack with only ane IAM role
+  await fixture.cdkDeploy('iam-roles', {
+    modEnv: {
+      NUMBER_OF_ROLES: '1',
+    },
+    options: [
+      '--context', `bootstrapBucket=${bootstrapBucketName}`,
+      '--toolkit-stack-name', toolkitStackName,
+      '--context', `@aws-cdk/core:bootstrapQualifier=${qualifier}`,
+    ],
+  });
+
+  // WHEN - adding 200 roles to the same stack to create a large diff
+  const diff = await fixture.cdk(['diff', fixture.fullStackName('iam-roles')], {
+    verbose: true,
+    modEnv: {
+      NUMBER_OF_ROLES: '200',
+    },
+    options: [
+      '--context', `bootstrapBucket=${bootstrapBucketName}`,
+      '--toolkit-stack-name', toolkitStackName,
+      '--context', `@aws-cdk/core:bootstrapQualifier=${qualifier}`,
+    ],
+  });
+
+  // Assert that the CLI assumes the file publishing role:
+  expect(diff).toMatch(/Assuming role .*file-publishing-role/);
+  expect(diff).toContain('success: Published');
+}));
+
 integTest(
   'cdk diff --security-only successfully outputs sso-permission-set-without-managed-policy information',
   withDefaultFixture(async (fixture) => {

packages/aws-cdk/lib/api/util/cloudformation.ts

@@ -305,6 +305,7 @@ export type PrepareChangeSetOptions = {
   sdkProvider: SdkProvider;
   stream: NodeJS.WritableStream;
   parameters: { [name: string]: string | undefined };
+  toolkitStackName?: string;
   resourcesToImport?: ResourcesToImport;
 }
 
@@ -375,9 +376,11 @@ async function uploadBodyParameterAndCreateChangeSet(options: PrepareChangeSetOp
       for (const entry of file_entries) {
         await options.deployments.buildSingleAsset(artifact, assetManifest, entry, {
           stack: options.stack,
+          toolkitStackName: options.toolkitStackName,
         });
         await options.deployments.publishSingleAsset(assetManifest, entry, {
           stack: options.stack,
+          toolkitStackName: options.toolkitStackName,
         });
       }
     }

packages/aws-cdk/lib/cdk-toolkit.ts

@@ -186,6 +186,7 @@ export class CdkToolkit {
               parameters: Object.assign({}, parameterMap['*'], parameterMap[stack.stackName]),
               resourcesToImport,
               stream,
+              toolkitStackName: options.toolkitStackName,
             });
           } else {
             debug(`the stack '${stack.stackName}' has not been deployed to CloudFormation or describeStacks call failed, skipping changeset creation.`);
@@ -1106,6 +1107,13 @@ export interface DiffOptions {
    */
   stackNames: string[];
 
+  /**
+   * Name of the toolkit stack, if not the default name
+   *
+   * @default 'CDKToolkit'
+   */
+  readonly toolkitStackName?: string;
+
   /**
    * Only select the given stack
    *

packages/aws-cdk/lib/cli.ts

@@ -526,6 +526,7 @@ export async function exec(args: string[], synthesizer?: Synthesizer): Promise<n
           compareAgainstProcessedTemplate: args.processed,
           quiet: args.quiet,
           changeSet: args['change-set'],
+          toolkitStackName: toolkitStackName,
         });
 
       case 'bootstrap':