feat(cli): support hotswapping Lambda function's description and envi…

…ronment variables (#21532)

CDK users who deploy their Lambda function with S3 code provider cannot use hotswap deployment today. It's because -- in order for the function version and alias to work -- they need to use a dynamic value in either function's description or environment variable. Since neither of them is supported by hotswap, CDK always performs a full deployment. 

This change allows Lambda function to be hotswappable when there's change in the function's description and/or environment variables. These changes are categorized as configuration changes and are updated by calling `updateFunctionConfiguration`. Since the existing waiter `UpdateFunctionCodeToFinish` is now used to wait for both code update and configuration update, I renamed it to `UpdateFunctionPropertiesToFinish`.

Functional wise, this PR is identical to the now-reverted changes in #21305. The only difference is the fix for integration test (commit [#82dbd4)](82dbd41)

resolves #20787

----


#21305


### All Submissions:

* [ X ] Have you followed the guidelines in our [Contributing guide?](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md)

### Adding new Unconventional Dependencies:

* [ ] This PR adds new unconventional dependencies following the process described [here](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md/#adding-new-unconventional-dependencies)

### New Features

* [ X ] Have you added the new feature to an [integration test](https://github.com/aws/aws-cdk/blob/main/INTEGRATION_TESTS.md)?
	* [  ] Did you use `yarn integ` to deploy the infrastructure and generate the snapshot (i.e. `yarn integ` without `--dry-run`)?

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

packages/aws-cdk/README.md

@@ -375,7 +375,8 @@ and that you have the necessary IAM permissions to update the resources that are
 Hotswapping is currently supported for the following changes
 (additional changes will be supported in the future):
 
-- Code asset (including Docker image and inline code) and tag changes of AWS Lambda functions.
+- Code asset (including Docker image and inline code), tag changes, and configuration changes (only
+  description and environment variables are supported) of AWS Lambda functions.
 - AWS Lambda Versions and Aliases changes.
 - Definition changes of AWS Step Functions State Machines.
 - Container asset changes of AWS ECS Services.

packages/aws-cdk/lib/api/hotswap/lambda-functions.ts

@@ -107,6 +107,8 @@ async function isLambdaFunctionCodeOnlyChange(
   const propertyUpdates = change.propertyUpdates;
   let code: LambdaFunctionCode | undefined = undefined;
   let tags: LambdaFunctionTags | undefined = undefined;
+  let description: string | undefined = undefined;
+  let environment: { [key: string]: string } | undefined = undefined;
 
   for (const updatedPropName in propertyUpdates) {
     const updatedProp = propertyUpdates[updatedPropName];
@@ -175,12 +177,19 @@ async function isLambdaFunctionCodeOnlyChange(
           tags = { tagUpdates };
         }
         break;
+      case 'Description':
+        description = updatedProp.newValue;
+        break;
+      case 'Environment':
+        environment = updatedProp.newValue;
+        break;
       default:
         return ChangeHotswapImpact.REQUIRES_FULL_DEPLOYMENT;
     }
   }
 
-  return code || tags ? { code, tags } : ChangeHotswapImpact.IRRELEVANT;
+  const configurations = description || environment ? { description, environment } : undefined;
+  return code || tags || configurations ? { code, tags, configurations } : ChangeHotswapImpact.IRRELEVANT;
 }
 
 interface CfnDiffTagValue {
@@ -203,9 +212,15 @@ interface LambdaFunctionTags {
   readonly tagUpdates: { [tag : string] : string | TagDeletion };
 }
 
+interface LambdaFunctionConfigurations {
+  readonly description?: string;
+  readonly environment?: { [key: string]: string };
+}
+
 interface LambdaFunctionChange {
   readonly code?: LambdaFunctionCode;
   readonly tags?: LambdaFunctionTags;
+  readonly configurations?: LambdaFunctionConfigurations;
 }
 
 interface LambdaFunctionResource {
@@ -235,16 +250,32 @@ class LambdaFunctionHotswapOperation implements HotswapOperation {
     const resource = this.lambdaFunctionResource.resource;
     const operations: Promise<any>[] = [];
 
-    if (resource.code !== undefined) {
-      const updateFunctionCodeResponse = await lambda.updateFunctionCode({
-        FunctionName: this.lambdaFunctionResource.physicalName,
-        S3Bucket: resource.code.s3Bucket,
-        S3Key: resource.code.s3Key,
-        ImageUri: resource.code.imageUri,
-        ZipFile: resource.code.functionCodeZip,
-      }).promise();
+    if (resource.code !== undefined || resource.configurations !== undefined) {
+      if (resource.code !== undefined) {
+        const updateFunctionCodeResponse = await lambda.updateFunctionCode({
+          FunctionName: this.lambdaFunctionResource.physicalName,
+          S3Bucket: resource.code.s3Bucket,
+          S3Key: resource.code.s3Key,
+          ImageUri: resource.code.imageUri,
+          ZipFile: resource.code.functionCodeZip,
+        }).promise();
+
+        await this.waitForLambdasPropertiesUpdateToFinish(updateFunctionCodeResponse, lambda);
+      }
 
-      await this.waitForLambdasCodeUpdateToFinish(updateFunctionCodeResponse, lambda);
+      if (resource.configurations !== undefined) {
+        const updateRequest: AWS.Lambda.UpdateFunctionConfigurationRequest = {
+          FunctionName: this.lambdaFunctionResource.physicalName,
+        };
+        if (resource.configurations.description !== undefined) {
+          updateRequest.Description = resource.configurations.description;
+        }
+        if (resource.configurations.environment !== undefined) {
+          updateRequest.Environment = resource.configurations.environment;
+        }
+        const updateFunctionCodeResponse = await lambda.updateFunctionConfiguration(updateRequest).promise();
+        await this.waitForLambdasPropertiesUpdateToFinish(updateFunctionCodeResponse, lambda);
+      }
 
       // only if the code changed is there any point in publishing a new Version
       if (this.lambdaFunctionResource.publishVersion) {
@@ -308,7 +339,9 @@ class LambdaFunctionHotswapOperation implements HotswapOperation {
    * or very slowly. For example, Zip based functions _not_ in a VPC can take ~1 second whereas VPC
    * or Container functions can take ~25 seconds (and 'idle' VPC functions can take minutes).
    */
-  private async waitForLambdasCodeUpdateToFinish(currentFunctionConfiguration: AWS.Lambda.FunctionConfiguration, lambda: AWS.Lambda): Promise<void> {
+  private async waitForLambdasPropertiesUpdateToFinish(
+    currentFunctionConfiguration: AWS.Lambda.FunctionConfiguration, lambda: AWS.Lambda,
+  ): Promise<void> {
     const functionIsInVpcOrUsesDockerForCode = currentFunctionConfiguration.VpcConfig?.VpcId ||
         currentFunctionConfiguration.PackageType === 'Image';
 
@@ -318,8 +351,8 @@ class LambdaFunctionHotswapOperation implements HotswapOperation {
     const delaySeconds = functionIsInVpcOrUsesDockerForCode ? 5 : 1;
 
     // configure a custom waiter to wait for the function update to complete
-    (lambda as any).api.waiters.updateFunctionCodeToFinish = {
-      name: 'UpdateFunctionCodeToFinish',
+    (lambda as any).api.waiters.updateFunctionPropertiesToFinish = {
+      name: 'UpdateFunctionPropertiesToFinish',
       operation: 'getFunction',
       // equates to 1 minute for zip function not in a VPC and
       // 5 minutes for container functions or function in a VPC
@@ -341,8 +374,8 @@ class LambdaFunctionHotswapOperation implements HotswapOperation {
       ],
     };
 
-    const updateFunctionCodeWaiter = new (AWS as any).ResourceWaiter(lambda, 'updateFunctionCodeToFinish');
-    await updateFunctionCodeWaiter.wait({
+    const updateFunctionPropertiesWaiter = new (AWS as any).ResourceWaiter(lambda, 'updateFunctionPropertiesToFinish');
+    await updateFunctionPropertiesWaiter.wait({
       FunctionName: this.lambdaFunctionResource.physicalName,
     }).promise();
   }

packages/aws-cdk/test/api/hotswap/lambda-functions-docker-hotswap-deployments.test.ts

@@ -119,8 +119,8 @@ test('calls the getFunction() API with a delay of 5', async () => {
   // THEN
   expect(mockMakeRequest).toHaveBeenCalledWith('getFunction', { FunctionName: 'my-function' });
   expect(hotswapMockSdkProvider.getLambdaApiWaiters()).toEqual(expect.objectContaining({
-    updateFunctionCodeToFinish: expect.objectContaining({
-      name: 'UpdateFunctionCodeToFinish',
+    updateFunctionPropertiesToFinish: expect.objectContaining({
+      name: 'UpdateFunctionPropertiesToFinish',
       delay: 5,
     }),
   }));

packages/aws-cdk/test/api/hotswap/lambda-functions-hotswap-deployments.test.ts

@@ -2,6 +2,9 @@ import { Lambda } from 'aws-sdk';
 import * as setup from './hotswap-test-setup';
 
 let mockUpdateLambdaCode: (params: Lambda.Types.UpdateFunctionCodeRequest) => Lambda.Types.FunctionConfiguration;
+let mockUpdateLambdaConfiguration: (
+  params: Lambda.Types.UpdateFunctionConfigurationRequest
+) => Lambda.Types.FunctionConfiguration;
 let mockTagResource: (params: Lambda.Types.TagResourceRequest) => {};
 let mockUntagResource: (params: Lambda.Types.UntagResourceRequest) => {};
 let mockMakeRequest: (operation: string, params: any) => AWS.Request<any, AWS.AWSError>;
@@ -10,6 +13,7 @@ let hotswapMockSdkProvider: setup.HotswapMockSdkProvider;
 beforeEach(() => {
   hotswapMockSdkProvider = setup.setupHotswapTests();
   mockUpdateLambdaCode = jest.fn().mockReturnValue({});
+  mockUpdateLambdaConfiguration = jest.fn().mockReturnValue({});
   mockTagResource = jest.fn();
   mockUntagResource = jest.fn();
   mockMakeRequest = jest.fn().mockReturnValue({
@@ -19,6 +23,7 @@ beforeEach(() => {
   });
   hotswapMockSdkProvider.stubLambda({
     updateFunctionCode: mockUpdateLambdaCode,
+    updateFunctionConfiguration: mockUpdateLambdaConfiguration,
     tagResource: mockTagResource,
     untagResource: mockUntagResource,
   }, {
@@ -593,8 +598,8 @@ test('calls getFunction() after function code is updated with delay 1', async ()
   // THEN
   expect(mockMakeRequest).toHaveBeenCalledWith('getFunction', { FunctionName: 'my-function' });
   expect(hotswapMockSdkProvider.getLambdaApiWaiters()).toEqual(expect.objectContaining({
-    updateFunctionCodeToFinish: expect.objectContaining({
-      name: 'UpdateFunctionCodeToFinish',
+    updateFunctionPropertiesToFinish: expect.objectContaining({
+      name: 'UpdateFunctionPropertiesToFinish',
       delay: 1,
     }),
   }));
@@ -654,8 +659,8 @@ test('calls getFunction() after function code is updated and VpcId is empty stri
 
   // THEN
   expect(hotswapMockSdkProvider.getLambdaApiWaiters()).toEqual(expect.objectContaining({
-    updateFunctionCodeToFinish: expect.objectContaining({
-      name: 'UpdateFunctionCodeToFinish',
+    updateFunctionPropertiesToFinish: expect.objectContaining({
+      name: 'UpdateFunctionPropertiesToFinish',
       delay: 1,
     }),
   }));
@@ -715,9 +720,188 @@ test('calls getFunction() after function code is updated on a VPC function with
 
   // THEN
   expect(hotswapMockSdkProvider.getLambdaApiWaiters()).toEqual(expect.objectContaining({
-    updateFunctionCodeToFinish: expect.objectContaining({
-      name: 'UpdateFunctionCodeToFinish',
+    updateFunctionPropertiesToFinish: expect.objectContaining({
+      name: 'UpdateFunctionPropertiesToFinish',
       delay: 5,
     }),
   }));
 });
+
+
+test('calls the updateLambdaConfiguration() API when it receives difference in Description field of a Lambda function', async () => {
+  // GIVEN
+  setup.setCurrentCfnStackTemplate({
+    Resources: {
+      Func: {
+        Type: 'AWS::Lambda::Function',
+        Properties: {
+          Code: {
+            S3Bucket: 's3-bucket',
+            S3Key: 's3-key',
+          },
+          FunctionName: 'my-function',
+          Description: 'Old Description',
+        },
+        Metadata: {
+          'aws:asset:path': 'asset-path',
+        },
+      },
+    },
+  });
+  const cdkStackArtifact = setup.cdkStackArtifactOf({
+    template: {
+      Resources: {
+        Func: {
+          Type: 'AWS::Lambda::Function',
+          Properties: {
+            Code: {
+              S3Bucket: 's3-bucket',
+              S3Key: 's3-key',
+            },
+            FunctionName: 'my-function',
+            Description: 'New Description',
+          },
+          Metadata: {
+            'aws:asset:path': 'asset-path',
+          },
+        },
+      },
+    },
+  });
+
+  // WHEN
+  const deployStackResult = await hotswapMockSdkProvider.tryHotswapDeployment(cdkStackArtifact);
+
+  // THEN
+  expect(deployStackResult).not.toBeUndefined();
+  expect(mockUpdateLambdaConfiguration).toHaveBeenCalledWith({
+    FunctionName: 'my-function',
+    Description: 'New Description',
+  });
+});
+
+test('calls the updateLambdaConfiguration() API when it receives difference in Environment field of a Lambda function', async () => {
+  // GIVEN
+  setup.setCurrentCfnStackTemplate({
+    Resources: {
+      Func: {
+        Type: 'AWS::Lambda::Function',
+        Properties: {
+          Code: {
+            S3Bucket: 's3-bucket',
+            S3Key: 's3-key',
+          },
+          FunctionName: 'my-function',
+          Environment: {
+            Variables: {
+              Key1: 'Value1',
+              Key2: 'Value2',
+            },
+          },
+        },
+        Metadata: {
+          'aws:asset:path': 'asset-path',
+        },
+      },
+    },
+  });
+  const cdkStackArtifact = setup.cdkStackArtifactOf({
+    template: {
+      Resources: {
+        Func: {
+          Type: 'AWS::Lambda::Function',
+          Properties: {
+            Code: {
+              S3Bucket: 's3-bucket',
+              S3Key: 's3-key',
+            },
+            FunctionName: 'my-function',
+            Environment: {
+              Variables: {
+                Key1: 'Value1',
+                Key2: 'Value2',
+                NewKey: 'NewValue',
+              },
+            },
+          },
+          Metadata: {
+            'aws:asset:path': 'asset-path',
+          },
+        },
+      },
+    },
+  });
+
+  // WHEN
+  const deployStackResult = await hotswapMockSdkProvider.tryHotswapDeployment(cdkStackArtifact);
+
+  // THEN
+  expect(deployStackResult).not.toBeUndefined();
+  expect(mockUpdateLambdaConfiguration).toHaveBeenCalledWith({
+    FunctionName: 'my-function',
+    Environment: {
+      Variables: {
+        Key1: 'Value1',
+        Key2: 'Value2',
+        NewKey: 'NewValue',
+      },
+    },
+  });
+});
+
+test('calls both updateLambdaCode() and updateLambdaConfiguration() API when it receives both code and configuration change', async () => {
+  // GIVEN
+  setup.setCurrentCfnStackTemplate({
+    Resources: {
+      Func: {
+        Type: 'AWS::Lambda::Function',
+        Properties: {
+          Code: {
+            S3Bucket: 'current-bucket',
+            S3Key: 'current-key',
+          },
+          FunctionName: 'my-function',
+          Description: 'Old Description',
+        },
+        Metadata: {
+          'aws:asset:path': 'asset-path',
+        },
+      },
+    },
+  });
+  const cdkStackArtifact = setup.cdkStackArtifactOf({
+    template: {
+      Resources: {
+        Func: {
+          Type: 'AWS::Lambda::Function',
+          Properties: {
+            Code: {
+              S3Bucket: 'new-bucket',
+              S3Key: 'new-key',
+            },
+            FunctionName: 'my-function',
+            Description: 'New Description',
+          },
+          Metadata: {
+            'aws:asset:path': 'asset-path',
+          },
+        },
+      },
+    },
+  });
+
+  // WHEN
+  const deployStackResult = await hotswapMockSdkProvider.tryHotswapDeployment(cdkStackArtifact);
+
+  // THEN
+  expect(deployStackResult).not.toBeUndefined();
+  expect(mockUpdateLambdaConfiguration).toHaveBeenCalledWith({
+    FunctionName: 'my-function',
+    Description: 'New Description',
+  });
+  expect(mockUpdateLambdaCode).toHaveBeenCalledWith({
+    FunctionName: 'my-function',
+    S3Bucket: 'new-bucket',
+    S3Key: 'new-key',
+  });
+});