feat(cli): support hotswapping Lambda functions that use Docker images

packages/aws-cdk/README.md

@@ -362,7 +362,7 @@ 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 and tag changes of AWS Lambda functions.
+- Code asset (including Docker image) and tag changes 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

@@ -108,7 +108,7 @@ async function isLambdaFunctionCodeOnlyChange(
     switch (updatedPropName) {
       case 'Code':
         let foundCodeDifference = false;
-        let s3Bucket = '', s3Key = '';
+        let s3Bucket, s3Key, imageUri;
 
         for (const newPropName in updatedProp.newValue) {
           switch (newPropName) {
@@ -120,6 +120,10 @@ async function isLambdaFunctionCodeOnlyChange(
               foundCodeDifference = true;
               s3Key = await evaluateCfnTemplate.evaluateCfnExpression(updatedProp.newValue[newPropName]);
               break;
+            case 'ImageUri':
+              foundCodeDifference = true;
+              imageUri = await evaluateCfnTemplate.evaluateCfnExpression(updatedProp.newValue[newPropName]);
+              break;
             default:
               return ChangeHotswapImpact.REQUIRES_FULL_DEPLOYMENT;
           }
@@ -128,6 +132,7 @@ async function isLambdaFunctionCodeOnlyChange(
           code = {
             s3Bucket,
             s3Key,
+            imageUri,
           };
         }
         break;
@@ -165,8 +170,9 @@ interface CfnDiffTagValue {
 }
 
 interface LambdaFunctionCode {
-  readonly s3Bucket: string;
-  readonly s3Key: string;
+  readonly s3Bucket?: string;
+  readonly s3Key?: string;
+  readonly imageUri?: string;
 }
 
 enum TagDeletion {
@@ -214,6 +220,7 @@ class LambdaFunctionHotswapOperation implements HotswapOperation {
         FunctionName: this.lambdaFunctionResource.physicalName,
         S3Bucket: resource.code.s3Bucket,
         S3Key: resource.code.s3Key,
+        ImageUri: resource.code.imageUri,
       }).promise();
 
       // only if the code changed is there any point in publishing a new Version

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

@@ -0,0 +1,67 @@
+import { Lambda } from 'aws-sdk';
+import * as setup from './hotswap-test-setup';
+
+let mockUpdateLambdaCode: (params: Lambda.Types.UpdateFunctionCodeRequest) => Lambda.Types.FunctionConfiguration;
+let mockTagResource: (params: Lambda.Types.TagResourceRequest) => {};
+let mockUntagResource: (params: Lambda.Types.UntagResourceRequest) => {};
+let hotswapMockSdkProvider: setup.HotswapMockSdkProvider;
+
+beforeEach(() => {
+  hotswapMockSdkProvider = setup.setupHotswapTests();
+  mockUpdateLambdaCode = jest.fn();
+  mockTagResource = jest.fn();
+  mockUntagResource = jest.fn();
+  hotswapMockSdkProvider.stubLambda({
+    updateFunctionCode: mockUpdateLambdaCode,
+    tagResource: mockTagResource,
+    untagResource: mockUntagResource,
+  });
+});
+
+test('calls the updateLambdaCode() API when it receives only a code difference in a Lambda function', async () => {
+  // GIVEN
+  setup.setCurrentCfnStackTemplate({
+    Resources: {
+      Func: {
+        Type: 'AWS::Lambda::Function',
+        Properties: {
+          Code: {
+            ImageUri: 'current-image',
+          },
+          FunctionName: 'my-function',
+        },
+        Metadata: {
+          'aws:asset:path': 'old-path',
+        },
+      },
+    },
+  });
+  const cdkStackArtifact = setup.cdkStackArtifactOf({
+    template: {
+      Resources: {
+        Func: {
+          Type: 'AWS::Lambda::Function',
+          Properties: {
+            Code: {
+              ImageUri: 'new-image',
+            },
+            FunctionName: 'my-function',
+          },
+          Metadata: {
+            'aws:asset:path': 'new-path',
+          },
+        },
+      },
+    },
+  });
+
+  // WHEN
+  const deployStackResult = await hotswapMockSdkProvider.tryHotswapDeployment(cdkStackArtifact);
+
+  // THEN
+  expect(deployStackResult).not.toBeUndefined();
+  expect(mockUpdateLambdaCode).toHaveBeenCalledWith({
+    FunctionName: 'my-function',
+    ImageUri: 'new-image',
+  });
+});