Update Lambda logging configuration to use non-deprecated AWS CDK properties

.changeset/silver-turkeys-argue.md

@@ -0,0 +1,5 @@
+---
+'@aws-amplify/backend-function': patch
+---
+
+Update lambda logging configuration to use non-deprecated AWS CDK properties

packages/backend-function/src/factory.test.ts

@@ -654,7 +654,7 @@ void describe('AmplifyFunctionFactory', () => {
   });
 
   void describe('logging options', () => {
-    void it('sets logging options', () => {
+    void it('sets logging options with log group', () => {
       const lambda = defineFunction({
         entry: './test-assets/default-lambda/handler.ts',
         bundling: {
@@ -667,15 +667,14 @@ void describe('AmplifyFunctionFactory', () => {
         },
       }).getInstance(getInstanceProps);
       const template = Template.fromStack(lambda.stack);
-      // Enabling log retention adds extra lambda.
-      template.resourceCountIs('AWS::Lambda::Function', 2);
-      const lambdas = template.findResources('AWS::Lambda::Function');
-      assert.ok(
-        Object.keys(lambdas).some((key) => key.startsWith('LogRetention')),
-      );
-      template.hasResourceProperties('Custom::LogRetention', {
+
+      // We now create a LogGroup directly rather than using the deprecated logRetention
+      template.resourceCountIs('AWS::Logs::LogGroup', 1);
+      template.hasResourceProperties('AWS::Logs::LogGroup', {
         RetentionInDays: 400,
       });
+
+      // The function should use the applicationLogLevelV2 and loggingFormat properties
       template.hasResourceProperties('AWS::Lambda::Function', {
         Handler: 'index.handler',
         LoggingConfig: {
@@ -684,6 +683,32 @@ void describe('AmplifyFunctionFactory', () => {
         },
       });
     });
+
+    void it('sets logging options without retention', () => {
+      const lambda = defineFunction({
+        entry: './test-assets/default-lambda/handler.ts',
+        bundling: {
+          minify: false,
+        },
+        logging: {
+          format: 'json',
+          level: 'info',
+        },
+      }).getInstance(getInstanceProps);
+      const template = Template.fromStack(lambda.stack);
+
+      // No log group should be created when retention is not specified
+      template.resourceCountIs('AWS::Logs::LogGroup', 0);
+
+      // The function should still have logging config
+      template.hasResourceProperties('AWS::Lambda::Function', {
+        Handler: 'index.handler',
+        LoggingConfig: {
+          ApplicationLogLevel: 'INFO',
+          LogFormat: 'JSON',
+        },
+      });
+    });
   });
 
   void describe('resourceAccessAcceptor', () => {

packages/backend-function/src/factory.ts

@@ -46,7 +46,10 @@ import * as path from 'path';
 import { FunctionEnvironmentTranslator } from './function_env_translator.js';
 import { FunctionEnvironmentTypeGenerator } from './function_env_type_generator.js';
 import { FunctionLayerArnParser } from './layer_parser.js';
-import { convertLoggingOptionsToCDK } from './logging_options_parser.js';
+import {
+  convertLoggingOptionsToCDK,
+  createLogGroup,
+} from './logging_options_parser.js';
 import { convertFunctionSchedulesToScheduleExpressions } from './schedule_parser.js';
 import {
   ProvidedFunctionFactory,
@@ -599,6 +602,13 @@ class AmplifyFunction
 
     let functionLambda: NodejsFunction;
     const cdkLoggingOptions = convertLoggingOptionsToCDK(props.logging);
+
+    // Create a log group if retention is specified (replacing deprecated logRetention property)
+    let logGroup = cdkLoggingOptions.logGroup;
+    if (props.logging.retention !== undefined && !logGroup) {
+      logGroup = createLogGroup(scope, id, props.logging);
+    }
+
     try {
       functionLambda = new NodejsFunction(scope, `${id}-lambda`, {
         entry: props.entry,
@@ -615,7 +625,7 @@ class AmplifyFunction
           externalModules: Object.keys(props.layers),
           logLevel: EsBuildLogLevel.ERROR,
         },
-        logRetention: cdkLoggingOptions.retention,
+        logGroup: logGroup,
         applicationLogLevelV2: cdkLoggingOptions.level,
         loggingFormat: cdkLoggingOptions.format,
       });

packages/backend-function/src/logging_options_parser.test.ts

@@ -4,22 +4,24 @@ import { FunctionLoggingOptions } from './factory.js';
 import {
   CDKLoggingOptions,
   convertLoggingOptionsToCDK,
+  createLogGroup,
 } from './logging_options_parser.js';
 import { ApplicationLogLevel, LoggingFormat } from 'aws-cdk-lib/aws-lambda';
-import { RetentionDays } from 'aws-cdk-lib/aws-logs';
+import { LogGroup } from 'aws-cdk-lib/aws-logs';
+import { App, Stack } from 'aws-cdk-lib';
+import { Template } from 'aws-cdk-lib/assertions';
 
-type TestCase = {
+type ConversionTestCase = {
   input: FunctionLoggingOptions;
   expectedOutput: CDKLoggingOptions;
 };
 
-const testCases: Array<TestCase> = [
+const conversionTestCases: Array<ConversionTestCase> = [
   {
     input: {},
     expectedOutput: {
       format: undefined,
       level: undefined,
-      retention: undefined,
     },
   },
   {
@@ -29,7 +31,6 @@ const testCases: Array<TestCase> = [
     },
     expectedOutput: {
       format: LoggingFormat.TEXT,
-      retention: RetentionDays.THIRTEEN_MONTHS,
       level: undefined,
     },
   },
@@ -40,17 +41,38 @@ const testCases: Array<TestCase> = [
     },
     expectedOutput: {
       format: LoggingFormat.JSON,
-      retention: undefined,
       level: ApplicationLogLevel.DEBUG,
     },
   },
 ];
 
 void describe('LoggingOptions converter', () => {
-  testCases.forEach((testCase, index) => {
+  conversionTestCases.forEach((testCase, index) => {
     void it(`converts to cdk options[${index}]`, () => {
       const convertedOptions = convertLoggingOptionsToCDK(testCase.input);
       assert.deepStrictEqual(convertedOptions, testCase.expectedOutput);
     });
   });
+
+  void it('createLogGroup creates a log group with proper retention', () => {
+    const app = new App();
+    const stack = new Stack(app, 'TestStack');
+    const logGroup = createLogGroup(stack, 'test-function', {
+      retention: '13 months',
+    });
+
+    // Check that the log group was created
+    assert.ok(logGroup instanceof LogGroup);
+
+    // Verify the synthesized CloudFormation template
+    const template = Template.fromStack(stack);
+
+    // Ensure we found exactly one log group
+    template.resourceCountIs('AWS::Logs::LogGroup', 1);
+
+    // Verify retention period (13 months = 400 days)
+    template.hasResourceProperties('AWS::Logs::LogGroup', {
+      RetentionInDays: 400,
+    });
+  });
 });

packages/backend-function/src/logging_options_parser.ts

@@ -4,16 +4,43 @@ import {
   LogLevelConverter,
   LogRetentionConverter,
 } from '@aws-amplify/platform-core/cdk';
-import { RetentionDays } from 'aws-cdk-lib/aws-logs';
+import { ILogGroup, LogGroup } from 'aws-cdk-lib/aws-logs';
+import { Construct } from 'constructs';
+import { RemovalPolicy } from 'aws-cdk-lib';
 
+/**
+ * CDK Lambda logging options using non-deprecated properties
+ * - level: ApplicationLogLevel for the lambda function (maps to applicationLogLevelV2)
+ * - format: Logging format (JSON or TEXT)
+ * - logGroup: Custom log group for the function (preferred over using logRetention directly)
+ */
 export type CDKLoggingOptions = {
   level?: ApplicationLogLevel;
-  retention?: RetentionDays;
   format?: LoggingFormat;
+  logGroup?: ILogGroup;
 };
 
 /**
- * Converts logging options to CDK.
+ * Creates a LogGroup with the specified retention settings
+ * This replaces the deprecated logRetention property on NodejsFunction
+ */
+export const createLogGroup = (
+  scope: Construct,
+  id: string,
+  loggingOptions: FunctionLoggingOptions,
+): ILogGroup => {
+  const retentionDays = new LogRetentionConverter().toCDKRetentionDays(
+    loggingOptions.retention,
+  );
+
+  return new LogGroup(scope, `${id}-log-group`, {
+    retention: retentionDays,
+    removalPolicy: RemovalPolicy.DESTROY, // This matches Lambda's default for auto-created log groups
+  });
+};
+
+/**
+ * Converts logging options to CDK format using non-deprecated properties
  */
 export const convertLoggingOptionsToCDK = (
   loggingOptions: FunctionLoggingOptions,
@@ -24,18 +51,18 @@ export const convertLoggingOptionsToCDK = (
       loggingOptions.level,
     );
   }
-  const retention = new LogRetentionConverter().toCDKRetentionDays(
-    loggingOptions.retention,
-  );
+
   const format = convertFormat(loggingOptions.format);
 
   return {
     level,
-    retention,
     format,
   };
 };
 
+/**
+ * Converts format string to LoggingFormat enum
+ */
 const convertFormat = (format: 'json' | 'text' | undefined) => {
   switch (format) {
     case undefined: