From 5a485e59b6ac908be436a8ae2cea77266ca546ef Mon Sep 17 00:00:00 2001
From: Calvin Combs <comcalvi@amazon.com>
Date: Thu, 14 Mar 2024 10:26:05 -0700
Subject: [PATCH 01/13] revert

---
 .../cloudformation-diff/lib/diff-template.ts  | 29 ++++---------------
 packages/aws-cdk/lib/cdk-toolkit.ts           | 26 +++--------------
 packages/aws-cdk/lib/diff.ts                  |  5 ++--
 3 files changed, 12 insertions(+), 48 deletions(-)

diff --git a/packages/@aws-cdk/cloudformation-diff/lib/diff-template.ts b/packages/@aws-cdk/cloudformation-diff/lib/diff-template.ts
index 284bb3a8d5f46..4bf1d29f57570 100644
--- a/packages/@aws-cdk/cloudformation-diff/lib/diff-template.ts
+++ b/packages/@aws-cdk/cloudformation-diff/lib/diff-template.ts
@@ -37,7 +37,6 @@ const DIFF_HANDLERS: HandlerRegistry = {
  * @param currentTemplate the current state of the stack.
  * @param newTemplate     the target state of the stack.
  * @param changeSet       the change set for this stack.
- * @param isImport        if the stack is importing resources (a migrate stack).
  *
  * @returns a +types.TemplateDiff+ object that represents the changes that will happen if
  *      a stack which current state is described by +currentTemplate+ is updated with
@@ -47,7 +46,6 @@ export function fullDiff(
   currentTemplate: { [key: string]: any },
   newTemplate: { [key: string]: any },
   changeSet?: CloudFormation.DescribeChangeSetOutput,
-  isImport?: boolean,
 ): types.TemplateDiff {
 
   normalize(currentTemplate);
@@ -57,9 +55,6 @@ export function fullDiff(
     filterFalsePositives(theDiff, changeSet);
     addImportInformation(theDiff, changeSet);
   }
-  if (isImport) {
-    addImportInformation(theDiff);
-  }
 
   return theDiff;
 }
@@ -214,25 +209,13 @@ function deepCopy(x: any): any {
   return x;
 }
 
-/**
- * Sets import flag to true for resource imports.
- * When the changeset parameter is not set, the stack is a new migrate stack,
- * so all resource changes are imports.
- */
-function addImportInformation(diff: types.TemplateDiff, changeSet?: CloudFormation.DescribeChangeSetOutput) {
-  if (changeSet) {
-    const imports = findResourceImports(changeSet);
-    diff.resources.forEachDifference((logicalId: string, change: types.ResourceDifference) => {
-      if (imports.includes(logicalId)) {
-        change.isImport = true;
-      }
-    });
-  } else {
-    diff.resources.forEachDifference((logicalId: string, change: types.ResourceDifference) => {
-      logicalId; // dont know how to get past warning that this variable is not used.
+function addImportInformation(diff: types.TemplateDiff, changeSet: CloudFormation.DescribeChangeSetOutput) {
+  const imports = findResourceImports(changeSet);
+  diff.resources.forEachDifference((logicalId: string, change: types.ResourceDifference) => {
+    if (imports.includes(logicalId)) {
       change.isImport = true;
-    });
-  }
+    }
+  });
 }
 
 function filterFalsePositives(diff: types.TemplateDiff, changeSet: CloudFormation.DescribeChangeSetOutput) {
diff --git a/packages/aws-cdk/lib/cdk-toolkit.ts b/packages/aws-cdk/lib/cdk-toolkit.ts
index 05aeee002c068..91ef83426d587 100644
--- a/packages/aws-cdk/lib/cdk-toolkit.ts
+++ b/packages/aws-cdk/lib/cdk-toolkit.ts
@@ -136,14 +136,7 @@ export class CdkToolkit {
         throw new Error(`There is no file at ${options.templatePath}`);
       }
 
-      const stackExistsOptions = {
-        stack: stacks.firstStack,
-        deployName: stacks.firstStack.stackName,
-      };
-
-      const stackExists = await this.props.deployments.stackExists(stackExistsOptions);
-
-      const changeSet = (stackExists && options.changeSet) ? await createDiffChangeSet({
+      const changeSet = options.changeSet ? await createDiffChangeSet({
         stack: stacks.firstStack,
         uuid: uuid.v4(),
         willExecute: false,
@@ -175,23 +168,13 @@ export class CdkToolkit {
           removeNonImportResources(stack);
         }
 
-        const stackExistsOptions = {
-          stack,
-          deployName: stack.stackName,
-        };
-
-        const stackExists = await this.props.deployments.stackExists(stackExistsOptions);
-
-        // if the stack does not already exist, do not do a changeset
-        // this prevents race conditions between deleting the dummy changeset stack and deploying the real changeset stack
-        // migrate stacks that import resources will not previously exist and default to old diff logic
-        const changeSet = (stackExists && options.changeSet) ? await createDiffChangeSet({
+        const changeSet = options.changeSet ? await createDiffChangeSet({
           stack,
           uuid: uuid.v4(),
           deployments: this.props.deployments,
           willExecute: false,
           sdkProvider: this.props.sdkProvider,
-          parameters: Object.assign({}, parameterMap['*'], parameterMap[stacks.firstStack.stackName]), // should this be stack?
+          parameters: Object.assign({}, parameterMap['*'], parameterMap[stacks.firstStack.stackName]),
           resourcesToImport,
           stream,
         }) : undefined;
@@ -200,11 +183,10 @@ export class CdkToolkit {
           stream.write('Parameters and rules created during migration do not affect resource configuration.\n');
         }
 
-        // pass a boolean to print if the stack is a migrate stack in order to set all resource diffs to import
         const stackCount =
         options.securityOnly
           ? (numberFromBool(printSecurityDiff(currentTemplate, stack, RequireApproval.Broadening, changeSet)))
-          : (printStackDiff(currentTemplate, stack, strict, contextLines, quiet, changeSet, stream, nestedStacks, !!resourcesToImport));
+          : (printStackDiff(currentTemplate, stack, strict, contextLines, quiet, changeSet, stream, nestedStacks));
 
         diffs += stackCount;
       }
diff --git a/packages/aws-cdk/lib/diff.ts b/packages/aws-cdk/lib/diff.ts
index b49f288fc2534..ce9c64eb4b443 100644
--- a/packages/aws-cdk/lib/diff.ts
+++ b/packages/aws-cdk/lib/diff.ts
@@ -26,10 +26,9 @@ export function printStackDiff(
   quiet: boolean,
   changeSet?: CloudFormation.DescribeChangeSetOutput,
   stream: cfnDiff.FormatStream = process.stderr,
-  nestedStackTemplates?: { [nestedStackLogicalId: string]: NestedStackTemplates },
-  isImport?: boolean): number {
+  nestedStackTemplates?: { [nestedStackLogicalId: string]: NestedStackTemplates }): number {
 
-  let diff = cfnDiff.fullDiff(oldTemplate, newTemplate.template, changeSet, isImport);
+  let diff = cfnDiff.fullDiff(oldTemplate, newTemplate.template, changeSet);
 
   // detect and filter out mangled characters from the diff
   let filteredChangesCount = 0;

From c8d5d9fb2ffaff7cea406259349894be50e746a0 Mon Sep 17 00:00:00 2001
From: Calvin Combs <comcalvi@amazon.com>
Date: Thu, 14 Mar 2024 14:17:48 -0700
Subject: [PATCH 02/13] diff does not create a changeset for a non-existant
 stack

---
 .../aws-cdk/lib/api/util/cloudformation.ts    | 21 +++++---------
 packages/aws-cdk/lib/cdk-toolkit.ts           | 28 ++++++++++++-------
 packages/aws-cdk/test/diff.test.ts            | 19 +++++++++++++
 3 files changed, 44 insertions(+), 24 deletions(-)

diff --git a/packages/aws-cdk/lib/api/util/cloudformation.ts b/packages/aws-cdk/lib/api/util/cloudformation.ts
index b61991bf51699..3176b88ab621b 100644
--- a/packages/aws-cdk/lib/api/util/cloudformation.ts
+++ b/packages/aws-cdk/lib/api/util/cloudformation.ts
@@ -364,7 +364,7 @@ async function uploadBodyParameterAndCreateChangeSet(options: PrepareChangeSetOp
 }
 
 async function createChangeSet(options: CreateChangeSetOptions): Promise<CloudFormation.DescribeChangeSetOutput> {
-  await cleanupOldChangeset(options.exists, options.changeSetName, options.stack.stackName, options.cfn);
+  await cleanupOldChangeset(options.changeSetName, options.stack.stackName, options.cfn);
 
   debug(`Attempting to create ChangeSet with name ${options.changeSetName} for stack ${options.stack.stackName}`);
 
@@ -388,23 +388,16 @@ async function createChangeSet(options: CreateChangeSetOptions): Promise<CloudFo
   debug('Initiated creation of changeset: %s; waiting for it to finish creating...', changeSet.Id);
   // Fetching all pages if we'll execute, so we can have the correct change count when monitoring.
   const createdChangeSet = await waitForChangeSet(options.cfn, options.stack.stackName, options.changeSetName, { fetchAll: options.willExecute });
-  await cleanupOldChangeset(options.exists, options.changeSetName, options.stack.stackName, options.cfn);
+  await cleanupOldChangeset(options.changeSetName, options.stack.stackName, options.cfn);
 
   return createdChangeSet;
 }
 
-export async function cleanupOldChangeset(stackExists: boolean, changeSetName: string, stackName: string, cfn: CloudFormation) {
-  if (stackExists) {
-    // Delete any existing change sets generated by CDK since change set names must be unique.
-    // The delete request is successful as long as the stack exists (even if the change set does not exist).
-    debug(`Removing existing change set with name ${changeSetName} if it exists`);
-    await cfn.deleteChangeSet({ StackName: stackName, ChangeSetName: changeSetName }).promise();
-  } else {
-    // delete the stack since creating a changeset for a stack that doesn't exist leaves that stack in a REVIEW_IN_PROGRESS state
-    // that prevents other changesets from being created, even after the changeset has been deleted.
-    debug(`Removing stack with name ${stackName}`);
-    await cfn.deleteStack({ StackName: stackName }).promise();
-  }
+export async function cleanupOldChangeset(changeSetName: string, stackName: string, cfn: CloudFormation) {
+  // Delete any existing change sets generated by CDK since change set names must be unique.
+  // The delete request is successful as long as the stack exists (even if the change set does not exist).
+  debug(`Removing existing change set with name ${changeSetName} if it exists`);
+  await cfn.deleteChangeSet({ StackName: stackName, ChangeSetName: changeSetName }).promise();
 }
 
 /**
diff --git a/packages/aws-cdk/lib/cdk-toolkit.ts b/packages/aws-cdk/lib/cdk-toolkit.ts
index 91ef83426d587..b08be9f5cb352 100644
--- a/packages/aws-cdk/lib/cdk-toolkit.ts
+++ b/packages/aws-cdk/lib/cdk-toolkit.ts
@@ -168,16 +168,24 @@ export class CdkToolkit {
           removeNonImportResources(stack);
         }
 
-        const changeSet = options.changeSet ? await createDiffChangeSet({
-          stack,
-          uuid: uuid.v4(),
-          deployments: this.props.deployments,
-          willExecute: false,
-          sdkProvider: this.props.sdkProvider,
-          parameters: Object.assign({}, parameterMap['*'], parameterMap[stacks.firstStack.stackName]),
-          resourcesToImport,
-          stream,
-        }) : undefined;
+        let changeSet = undefined;
+
+        if (options.changeSet) {
+          const stackExists = await this.props.deployments.stackExists({
+            stack: stack,
+            deployName: stack.stackName,
+          });
+          changeSet = stackExists ? await createDiffChangeSet({
+            stack,
+            uuid: uuid.v4(),
+            deployments: this.props.deployments,
+            willExecute: false,
+            sdkProvider: this.props.sdkProvider,
+            parameters: Object.assign({}, parameterMap['*'], parameterMap[stacks.firstStack.stackName]),
+            resourcesToImport,
+            stream,
+          }) : undefined;
+        }
 
         if (resourcesToImport) {
           stream.write('Parameters and rules created during migration do not affect resource configuration.\n');
diff --git a/packages/aws-cdk/test/diff.test.ts b/packages/aws-cdk/test/diff.test.ts
index 8dd11bb0b5fce..956efb4d76c3a 100644
--- a/packages/aws-cdk/test/diff.test.ts
+++ b/packages/aws-cdk/test/diff.test.ts
@@ -67,6 +67,7 @@ describe('imports', () => {
     });
 
     cloudFormation = instanceMockFrom(Deployments);
+    cloudFormation.stackExists = jest.fn().mockReturnValue(Promise.resolve(true));
 
     toolkit = new CdkToolkit({
       cloudExecutable,
@@ -306,6 +307,24 @@ describe('non-nested stacks', () => {
     expect(buffer.data.trim()).not.toContain('There were no differences');
     expect(exitCode).toBe(0);
   });
+
+  test('diff does not check for stack existance when --no-changeset is passed', async () => {
+    // GIVEN
+    const buffer = new StringWritable();
+
+    // WHEN
+    const exitCode = await toolkit.diff({
+      stackNames: ['A', 'A'],
+      stream: buffer,
+      fail: false,
+      quiet: true,
+      changeSet: false,
+    });
+
+    // THEN
+    expect(exitCode).toBe(0);
+    expect(cloudFormation.stackExists).not.toHaveBeenCalled();
+  });
 });
 
 describe('nested stacks', () => {

From c49b58949d5968183661f56fd6d577a84197c2cf Mon Sep 17 00:00:00 2001
From: Calvin Combs <comcalvi@amazon.com>
Date: Thu, 14 Mar 2024 14:24:02 -0700
Subject: [PATCH 03/13] fixed template case

---
 packages/aws-cdk/lib/cdk-toolkit.ts | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/packages/aws-cdk/lib/cdk-toolkit.ts b/packages/aws-cdk/lib/cdk-toolkit.ts
index b08be9f5cb352..7a67eaf2e23f9 100644
--- a/packages/aws-cdk/lib/cdk-toolkit.ts
+++ b/packages/aws-cdk/lib/cdk-toolkit.ts
@@ -136,15 +136,23 @@ export class CdkToolkit {
         throw new Error(`There is no file at ${options.templatePath}`);
       }
 
-      const changeSet = options.changeSet ? await createDiffChangeSet({
-        stack: stacks.firstStack,
-        uuid: uuid.v4(),
-        willExecute: false,
-        deployments: this.props.deployments,
-        sdkProvider: this.props.sdkProvider,
-        parameters: Object.assign({}, parameterMap['*'], parameterMap[stacks.firstStack.stackName]),
-        stream,
-      }) : undefined;
+      let changeSet = undefined;
+
+      if (options.changeSet) {
+        const stackExists = await this.props.deployments.stackExists({
+          stack: stacks.firstStack,
+          deployName: stacks.firstStack.stackName,
+        });
+        changeSet = stackExists ? await createDiffChangeSet({
+          stack: stacks.firstStack,
+          uuid: uuid.v4(),
+          willExecute: false,
+          deployments: this.props.deployments,
+          sdkProvider: this.props.sdkProvider,
+          parameters: Object.assign({}, parameterMap['*'], parameterMap[stacks.firstStack.stackName]),
+          stream,
+        }) : undefined;
+      }
 
       const template = deserializeStructure(await fs.readFile(options.templatePath, { encoding: 'UTF-8' }));
       diffs = options.securityOnly

From f1177006005b84ca32b97a48e7206de6edbb6489 Mon Sep 17 00:00:00 2001
From: Calvin Combs <comcalvi@amazon.com>
Date: Thu, 14 Mar 2024 14:27:55 -0700
Subject: [PATCH 04/13] refactor

---
 packages/aws-cdk/lib/cdk-toolkit.ts | 46 +++++++++++++++++------------
 1 file changed, 27 insertions(+), 19 deletions(-)

diff --git a/packages/aws-cdk/lib/cdk-toolkit.ts b/packages/aws-cdk/lib/cdk-toolkit.ts
index 7a67eaf2e23f9..a2c44e1767921 100644
--- a/packages/aws-cdk/lib/cdk-toolkit.ts
+++ b/packages/aws-cdk/lib/cdk-toolkit.ts
@@ -143,15 +143,19 @@ export class CdkToolkit {
           stack: stacks.firstStack,
           deployName: stacks.firstStack.stackName,
         });
-        changeSet = stackExists ? await createDiffChangeSet({
-          stack: stacks.firstStack,
-          uuid: uuid.v4(),
-          willExecute: false,
-          deployments: this.props.deployments,
-          sdkProvider: this.props.sdkProvider,
-          parameters: Object.assign({}, parameterMap['*'], parameterMap[stacks.firstStack.stackName]),
-          stream,
-        }) : undefined;
+        if (stackExists) {
+          changeSet = await createDiffChangeSet({
+            stack: stacks.firstStack,
+            uuid: uuid.v4(),
+            deployments: this.props.deployments,
+            willExecute: false,
+            sdkProvider: this.props.sdkProvider,
+            parameters: Object.assign({}, parameterMap['*'], parameterMap[stacks.firstStack.stackName]),
+            stream,
+          });
+        } else {
+          debug(`the stack '${stacks.firstStack.stackName}' does not exist, skipping changeset creation.`);
+        }
       }
 
       const template = deserializeStructure(await fs.readFile(options.templatePath, { encoding: 'UTF-8' }));
@@ -183,16 +187,20 @@ export class CdkToolkit {
             stack: stack,
             deployName: stack.stackName,
           });
-          changeSet = stackExists ? await createDiffChangeSet({
-            stack,
-            uuid: uuid.v4(),
-            deployments: this.props.deployments,
-            willExecute: false,
-            sdkProvider: this.props.sdkProvider,
-            parameters: Object.assign({}, parameterMap['*'], parameterMap[stacks.firstStack.stackName]),
-            resourcesToImport,
-            stream,
-          }) : undefined;
+          if (stackExists) {
+            changeSet = await createDiffChangeSet({
+              stack,
+              uuid: uuid.v4(),
+              deployments: this.props.deployments,
+              willExecute: false,
+              sdkProvider: this.props.sdkProvider,
+              parameters: Object.assign({}, parameterMap['*'], parameterMap[stacks.firstStack.stackName]),
+              resourcesToImport,
+              stream,
+            });
+          } else {
+            debug(`the stack '${stack.stackName}' does not exist, skipping changeset creation.`);
+          }
         }
 
         if (resourcesToImport) {

From 0e22c53d13fc6f17fe172a876616d63de9c437fc Mon Sep 17 00:00:00 2001
From: Calvin Combs <comcalvi@amazon.com>
Date: Fri, 15 Mar 2024 09:16:22 -0700
Subject: [PATCH 05/13] works for migrate stacks

---
 packages/aws-cdk/lib/api/util/cloudformation.ts | 6 +++++-
 packages/aws-cdk/lib/cdk-toolkit.ts             | 6 +++---
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/packages/aws-cdk/lib/api/util/cloudformation.ts b/packages/aws-cdk/lib/api/util/cloudformation.ts
index 3176b88ab621b..41d170c3ba386 100644
--- a/packages/aws-cdk/lib/api/util/cloudformation.ts
+++ b/packages/aws-cdk/lib/api/util/cloudformation.ts
@@ -397,7 +397,11 @@ export async function cleanupOldChangeset(changeSetName: string, stackName: stri
   // Delete any existing change sets generated by CDK since change set names must be unique.
   // The delete request is successful as long as the stack exists (even if the change set does not exist).
   debug(`Removing existing change set with name ${changeSetName} if it exists`);
-  await cfn.deleteChangeSet({ StackName: stackName, ChangeSetName: changeSetName }).promise();
+  try {
+    await cfn.deleteChangeSet({ StackName: stackName, ChangeSetName: changeSetName }).promise();
+  } catch (e) {
+    debug(`no changeset to clean up for stack ${stackName}`);
+  }
 }
 
 /**
diff --git a/packages/aws-cdk/lib/cdk-toolkit.ts b/packages/aws-cdk/lib/cdk-toolkit.ts
index a2c44e1767921..bab08de98dc91 100644
--- a/packages/aws-cdk/lib/cdk-toolkit.ts
+++ b/packages/aws-cdk/lib/cdk-toolkit.ts
@@ -187,19 +187,19 @@ export class CdkToolkit {
             stack: stack,
             deployName: stack.stackName,
           });
-          if (stackExists) {
+          if (stackExists || resourcesToImport) {
             changeSet = await createDiffChangeSet({
               stack,
               uuid: uuid.v4(),
               deployments: this.props.deployments,
               willExecute: false,
               sdkProvider: this.props.sdkProvider,
-              parameters: Object.assign({}, parameterMap['*'], parameterMap[stacks.firstStack.stackName]),
+              parameters: Object.assign({}, parameterMap['*'], parameterMap[stack.stackName]),
               resourcesToImport,
               stream,
             });
           } else {
-            debug(`the stack '${stack.stackName}' does not exist, skipping changeset creation.`);
+            debug(`the stack '${stack.stackName}' does not exist and we are not importing resources, skipping changeset creation.`);
           }
         }
 

From 3cf8c60499c17a6dfb4cc69ad2f01931ba490d6d Mon Sep 17 00:00:00 2001
From: Calvin Combs <comcalvi@amazon.com>
Date: Fri, 15 Mar 2024 09:58:48 -0700
Subject: [PATCH 06/13] tests

---
 packages/aws-cdk/test/diff.test.ts | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/packages/aws-cdk/test/diff.test.ts b/packages/aws-cdk/test/diff.test.ts
index 956efb4d76c3a..c56102e9ed7a8 100644
--- a/packages/aws-cdk/test/diff.test.ts
+++ b/packages/aws-cdk/test/diff.test.ts
@@ -67,7 +67,6 @@ describe('imports', () => {
     });
 
     cloudFormation = instanceMockFrom(Deployments);
-    cloudFormation.stackExists = jest.fn().mockReturnValue(Promise.resolve(true));
 
     toolkit = new CdkToolkit({
       cloudExecutable,
@@ -95,9 +94,36 @@ describe('imports', () => {
     fs.rmSync('migrate.json');
   });
 
-  test('imports', async () => {
+  test('imports render correctly for a nonexistant stack', async () => {
+    // GIVEN
+    const buffer = new StringWritable();
+    cloudFormation.stackExists = jest.fn().mockReturnValue(Promise.resolve(false));
+
+    // WHEN
+    const exitCode = await toolkit.diff({
+      stackNames: ['A'],
+      stream: buffer,
+      changeSet: true,
+    });
+
+    // THEN
+    const plainTextOutput = buffer.data.replace(/\x1B\[[0-?]*[ -/]*[@-~]/g, '');
+    expect(plainTextOutput).toContain(`Stack A
+Parameters and rules created during migration do not affect resource configuration.
+Resources
+[←] AWS::SQS::Queue Queue import
+[←] AWS::SQS::Queue Queue2 import
+[←] AWS::S3::Bucket Bucket import
+`);
+
+    expect(buffer.data.trim()).toContain('✨  Number of stacks with differences: 1');
+    expect(exitCode).toBe(0);
+  });
+
+  test('imports render correctly for an existing stack', async () => {
     // GIVEN
     const buffer = new StringWritable();
+    cloudFormation.stackExists = jest.fn().mockReturnValue(Promise.resolve(true));
 
     // WHEN
     const exitCode = await toolkit.diff({

From be42b4ec61a51acd82093d59c0a96a2799719329 Mon Sep 17 00:00:00 2001
From: Calvin Combs <comcalvi@amazon.com>
Date: Fri, 15 Mar 2024 10:09:36 -0700
Subject: [PATCH 07/13] cosmetic

---
 packages/aws-cdk/lib/cdk-toolkit.ts | 1 +
 packages/aws-cdk/test/diff.test.ts  | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/packages/aws-cdk/lib/cdk-toolkit.ts b/packages/aws-cdk/lib/cdk-toolkit.ts
index bab08de98dc91..745fdf90ca333 100644
--- a/packages/aws-cdk/lib/cdk-toolkit.ts
+++ b/packages/aws-cdk/lib/cdk-toolkit.ts
@@ -183,6 +183,7 @@ export class CdkToolkit {
         let changeSet = undefined;
 
         if (options.changeSet) {
+          // only perform this check if we're going to make a changeset. This check requires permissions that --no-changeset users might not have.
           const stackExists = await this.props.deployments.stackExists({
             stack: stack,
             deployName: stack.stackName,
diff --git a/packages/aws-cdk/test/diff.test.ts b/packages/aws-cdk/test/diff.test.ts
index c56102e9ed7a8..79429830cbf6e 100644
--- a/packages/aws-cdk/test/diff.test.ts
+++ b/packages/aws-cdk/test/diff.test.ts
@@ -334,7 +334,7 @@ describe('non-nested stacks', () => {
     expect(exitCode).toBe(0);
   });
 
-  test('diff does not check for stack existance when --no-changeset is passed', async () => {
+  test('diff does not check for stack existence when --no-changeset is passed', async () => {
     // GIVEN
     const buffer = new StringWritable();
 

From 1b8f8ef621794524ddd39f2030bda23235fd7f51 Mon Sep 17 00:00:00 2001
From: Calvin Combs <comcalvi@amazon.com>
Date: Fri, 15 Mar 2024 12:10:50 -0700
Subject: [PATCH 08/13] don't create a changeset if the stack doesn't exist...

---
 .../@aws-cdk/cloudformation-diff/lib/diff-template.ts  | 10 ++++++++++
 packages/aws-cdk/lib/cdk-toolkit.ts                    |  6 +++---
 packages/aws-cdk/lib/diff.ts                           |  4 +++-
 packages/aws-cdk/test/diff.test.ts                     |  6 ++++--
 4 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/packages/@aws-cdk/cloudformation-diff/lib/diff-template.ts b/packages/@aws-cdk/cloudformation-diff/lib/diff-template.ts
index 4bf1d29f57570..5252087f1f215 100644
--- a/packages/@aws-cdk/cloudformation-diff/lib/diff-template.ts
+++ b/packages/@aws-cdk/cloudformation-diff/lib/diff-template.ts
@@ -46,6 +46,7 @@ export function fullDiff(
   currentTemplate: { [key: string]: any },
   newTemplate: { [key: string]: any },
   changeSet?: CloudFormation.DescribeChangeSetOutput,
+  isImport?: boolean,
 ): types.TemplateDiff {
 
   normalize(currentTemplate);
@@ -55,6 +56,9 @@ export function fullDiff(
     filterFalsePositives(theDiff, changeSet);
     addImportInformation(theDiff, changeSet);
   }
+  if (isImport) {
+    makeAllResourceChangesImports(theDiff);
+  }
 
   return theDiff;
 }
@@ -218,6 +222,12 @@ function addImportInformation(diff: types.TemplateDiff, changeSet: CloudFormatio
   });
 }
 
+function makeAllResourceChangesImports(diff: types.TemplateDiff) {
+  diff.resources.forEachDifference((_logicalId: string, change: types.ResourceDifference) => {
+    change.isImport = true;
+  });
+}
+
 function filterFalsePositives(diff: types.TemplateDiff, changeSet: CloudFormation.DescribeChangeSetOutput) {
   const replacements = findResourceReplacements(changeSet);
   diff.resources.forEachDifference((logicalId: string, change: types.ResourceDifference) => {
diff --git a/packages/aws-cdk/lib/cdk-toolkit.ts b/packages/aws-cdk/lib/cdk-toolkit.ts
index 745fdf90ca333..b06ac98d42211 100644
--- a/packages/aws-cdk/lib/cdk-toolkit.ts
+++ b/packages/aws-cdk/lib/cdk-toolkit.ts
@@ -161,7 +161,7 @@ export class CdkToolkit {
       const template = deserializeStructure(await fs.readFile(options.templatePath, { encoding: 'UTF-8' }));
       diffs = options.securityOnly
         ? numberFromBool(printSecurityDiff(template, stacks.firstStack, RequireApproval.Broadening, changeSet))
-        : printStackDiff(template, stacks.firstStack.template, strict, contextLines, quiet, changeSet, stream);
+        : printStackDiff(template, stacks.firstStack.template, strict, contextLines, quiet, changeSet, false, stream);
     } else {
       // Compare N stacks against deployed templates
       for (const stack of stacks.stackArtifacts) {
@@ -188,7 +188,7 @@ export class CdkToolkit {
             stack: stack,
             deployName: stack.stackName,
           });
-          if (stackExists || resourcesToImport) {
+          if (stackExists) {
             changeSet = await createDiffChangeSet({
               stack,
               uuid: uuid.v4(),
@@ -211,7 +211,7 @@ export class CdkToolkit {
         const stackCount =
         options.securityOnly
           ? (numberFromBool(printSecurityDiff(currentTemplate, stack, RequireApproval.Broadening, changeSet)))
-          : (printStackDiff(currentTemplate, stack, strict, contextLines, quiet, changeSet, stream, nestedStacks));
+          : (printStackDiff(currentTemplate, stack, strict, contextLines, quiet, changeSet, !!resourcesToImport, stream, nestedStacks));
 
         diffs += stackCount;
       }
diff --git a/packages/aws-cdk/lib/diff.ts b/packages/aws-cdk/lib/diff.ts
index ce9c64eb4b443..cc5cb3d3567fa 100644
--- a/packages/aws-cdk/lib/diff.ts
+++ b/packages/aws-cdk/lib/diff.ts
@@ -25,10 +25,11 @@ export function printStackDiff(
   context: number,
   quiet: boolean,
   changeSet?: CloudFormation.DescribeChangeSetOutput,
+  isImport?: boolean,
   stream: cfnDiff.FormatStream = process.stderr,
   nestedStackTemplates?: { [nestedStackLogicalId: string]: NestedStackTemplates }): number {
 
-  let diff = cfnDiff.fullDiff(oldTemplate, newTemplate.template, changeSet);
+  let diff = cfnDiff.fullDiff(oldTemplate, newTemplate.template, changeSet, isImport);
 
   // detect and filter out mangled characters from the diff
   let filteredChangesCount = 0;
@@ -82,6 +83,7 @@ export function printStackDiff(
       context,
       quiet,
       undefined,
+      isImport,
       stream,
       nestedStack.nestedStackTemplates,
     );
diff --git a/packages/aws-cdk/test/diff.test.ts b/packages/aws-cdk/test/diff.test.ts
index 79429830cbf6e..e120103390087 100644
--- a/packages/aws-cdk/test/diff.test.ts
+++ b/packages/aws-cdk/test/diff.test.ts
@@ -94,7 +94,7 @@ describe('imports', () => {
     fs.rmSync('migrate.json');
   });
 
-  test('imports render correctly for a nonexistant stack', async () => {
+  test('imports render correctly for a nonexistant stack without creating a changeset', async () => {
     // GIVEN
     const buffer = new StringWritable();
     cloudFormation.stackExists = jest.fn().mockReturnValue(Promise.resolve(false));
@@ -108,6 +108,7 @@ describe('imports', () => {
 
     // THEN
     const plainTextOutput = buffer.data.replace(/\x1B\[[0-?]*[ -/]*[@-~]/g, '');
+    expect(cfn.createDiffChangeSet).not.toHaveBeenCalled();
     expect(plainTextOutput).toContain(`Stack A
 Parameters and rules created during migration do not affect resource configuration.
 Resources
@@ -120,7 +121,7 @@ Resources
     expect(exitCode).toBe(0);
   });
 
-  test('imports render correctly for an existing stack', async () => {
+  test('imports render correctly for an existing stack and diff creates a changeset', async () => {
     // GIVEN
     const buffer = new StringWritable();
     cloudFormation.stackExists = jest.fn().mockReturnValue(Promise.resolve(true));
@@ -134,6 +135,7 @@ Resources
 
     // THEN
     const plainTextOutput = buffer.data.replace(/\x1B\[[0-?]*[ -/]*[@-~]/g, '');
+    expect(cfn.createDiffChangeSet).toHaveBeenCalled();
     expect(plainTextOutput).toContain(`Stack A
 Parameters and rules created during migration do not affect resource configuration.
 Resources

From fc9f74eb2c9c76e7dca153a912eb2a188f7afedf Mon Sep 17 00:00:00 2001
From: Calvin Combs <comcalvi@amazon.com>
Date: Fri, 15 Mar 2024 12:17:56 -0700
Subject: [PATCH 09/13] unneeded

---
 packages/aws-cdk/lib/api/util/cloudformation.ts | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/packages/aws-cdk/lib/api/util/cloudformation.ts b/packages/aws-cdk/lib/api/util/cloudformation.ts
index 41d170c3ba386..3176b88ab621b 100644
--- a/packages/aws-cdk/lib/api/util/cloudformation.ts
+++ b/packages/aws-cdk/lib/api/util/cloudformation.ts
@@ -397,11 +397,7 @@ export async function cleanupOldChangeset(changeSetName: string, stackName: stri
   // Delete any existing change sets generated by CDK since change set names must be unique.
   // The delete request is successful as long as the stack exists (even if the change set does not exist).
   debug(`Removing existing change set with name ${changeSetName} if it exists`);
-  try {
-    await cfn.deleteChangeSet({ StackName: stackName, ChangeSetName: changeSetName }).promise();
-  } catch (e) {
-    debug(`no changeset to clean up for stack ${stackName}`);
-  }
+  await cfn.deleteChangeSet({ StackName: stackName, ChangeSetName: changeSetName }).promise();
 }
 
 /**

From 2a4819bd46d5e0e35543ff04902eb4c80c8ab514 Mon Sep 17 00:00:00 2001
From: Calvin Combs <comcalvi@amazon.com>
Date: Fri, 15 Mar 2024 12:21:21 -0700
Subject: [PATCH 10/13] logging

---
 packages/aws-cdk/lib/cdk-toolkit.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/aws-cdk/lib/cdk-toolkit.ts b/packages/aws-cdk/lib/cdk-toolkit.ts
index b06ac98d42211..fb075a8d3a3de 100644
--- a/packages/aws-cdk/lib/cdk-toolkit.ts
+++ b/packages/aws-cdk/lib/cdk-toolkit.ts
@@ -200,7 +200,7 @@ export class CdkToolkit {
               stream,
             });
           } else {
-            debug(`the stack '${stack.stackName}' does not exist and we are not importing resources, skipping changeset creation.`);
+            debug(`the stack '${stack.stackName}' does not exist, skipping changeset creation.`);
           }
         }
 

From 0edd606287141270f9d8bbd378f72ab2bfec54f2 Mon Sep 17 00:00:00 2001
From: Calvin Combs <comcalvi@amazon.com>
Date: Fri, 15 Mar 2024 12:22:32 -0700
Subject: [PATCH 11/13] branching was wrong

---
 packages/@aws-cdk/cloudformation-diff/lib/diff-template.ts | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/@aws-cdk/cloudformation-diff/lib/diff-template.ts b/packages/@aws-cdk/cloudformation-diff/lib/diff-template.ts
index 5252087f1f215..76f7f161f892d 100644
--- a/packages/@aws-cdk/cloudformation-diff/lib/diff-template.ts
+++ b/packages/@aws-cdk/cloudformation-diff/lib/diff-template.ts
@@ -55,8 +55,7 @@ export function fullDiff(
   if (changeSet) {
     filterFalsePositives(theDiff, changeSet);
     addImportInformation(theDiff, changeSet);
-  }
-  if (isImport) {
+  } else if (isImport) {
     makeAllResourceChangesImports(theDiff);
   }
 

From 898e429cfed2ed71bcddc6d8a29fca60d3ac1e7b Mon Sep 17 00:00:00 2001
From: Calvin Combs <66279577+comcalvi@users.noreply.github.com>
Date: Fri, 15 Mar 2024 13:32:52 -0700
Subject: [PATCH 12/13] logging

Co-authored-by: Parker Scanlon <69879391+scanlonp@users.noreply.github.com>
---
 packages/aws-cdk/lib/cdk-toolkit.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/aws-cdk/lib/cdk-toolkit.ts b/packages/aws-cdk/lib/cdk-toolkit.ts
index fb075a8d3a3de..f0d350ec08839 100644
--- a/packages/aws-cdk/lib/cdk-toolkit.ts
+++ b/packages/aws-cdk/lib/cdk-toolkit.ts
@@ -200,7 +200,7 @@ export class CdkToolkit {
               stream,
             });
           } else {
-            debug(`the stack '${stack.stackName}' does not exist, skipping changeset creation.`);
+            debug(`the stack '${stack.stackName}' has not been deployed to CloudFormation, skipping changeset creation.`);
           }
         }
 

From 9b2178c1ddd2098cc1945384fe956d387477987e Mon Sep 17 00:00:00 2001
From: Calvin Combs <comcalvi@amazon.com>
Date: Fri, 15 Mar 2024 13:35:09 -0700
Subject: [PATCH 13/13] logging

---
 packages/aws-cdk/lib/cdk-toolkit.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/aws-cdk/lib/cdk-toolkit.ts b/packages/aws-cdk/lib/cdk-toolkit.ts
index fb075a8d3a3de..627328fcd35f0 100644
--- a/packages/aws-cdk/lib/cdk-toolkit.ts
+++ b/packages/aws-cdk/lib/cdk-toolkit.ts
@@ -154,7 +154,7 @@ export class CdkToolkit {
             stream,
           });
         } else {
-          debug(`the stack '${stacks.firstStack.stackName}' does not exist, skipping changeset creation.`);
+          debug(`the stack '${stacks.firstStack.stackName}' has not been deployed to CloudFormation, skipping changeset creation.`);
         }
       }