Add Saga Pattern Implementation with Lambda Durable Functions and CDK

saga-pattern-lambda-durable-functions/saga-pattern-cdk/.gitignore

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+*.js
+!jest.config.js
+*.d.ts
+node_modules
+
+# CDK asset staging directory
+.cdk.staging
+cdk.out

saga-pattern-lambda-durable-functions/saga-pattern-cdk/.npmignore

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+*.ts
+!*.d.ts
+
+# CDK asset staging directory
+.cdk.staging
+cdk.out

saga-pattern-lambda-durable-functions/saga-pattern-cdk/README.md

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+# Saga Pattern with Lambda Durable Functions
+
+This CDK project implements the saga pattern for distributed transactions using AWS Lambda Durable Functions. It demonstrates how to coordinate multiple microservices (flight, hotel, and car rental) with automatic rollback capabilities when any step fails.
+
+## Architecture Overview
+
+The saga orchestrator coordinates a travel booking workflow that:
+1. Reserves a flight
+2. Reserves a hotel room
+3. Reserves a car rental
+
+If any step fails, the orchestrator automatically executes compensating transactions to rollback previously completed reservations, ensuring data consistency across all services.
+
+## Components
+
+### Lambda Functions
+
+**Saga Orchestrator (Durable Function)**
+- Coordinates the entire workflow across all three services
+- Manages state and execution history
+- Automatically triggers rollback on failure
+- Execution timeout: 1 hour
+- Retention period: 30 days
+
+**Flight Service**
+- `saga-reserve-flight`: Creates flight booking reservations
+- `saga-cancel-flight`: Compensating transaction to cancel flight bookings
+
+**Hotel Service**
+- `saga-reserve-hotel`: Creates hotel room reservations
+- `saga-cancel-hotel`: Compensating transaction to cancel hotel reservations
+
+**Car Service**
+- `saga-reserve-car`: Creates car rental reservations
+- `saga-cancel-car`: Compensating transaction to cancel car rentals
+
+### DynamoDB Tables
+
+- `saga-flight-bookings`: Stores flight booking records
+- `saga-hotel-reservations`: Stores hotel reservation records
+- `saga-car-rentals`: Stores car rental records
+
+All tables use:
+- Pay-per-request billing mode
+- Point-in-time recovery enabled
+- Partition key based on reservation/booking/rental ID
+
+## Prerequisites
+
+- Node.js and npm installed
+- AWS CDK CLI installed (`npm install -g aws-cdk`)
+- AWS credentials configured
+- Python 3.14 runtime available in your AWS region
+
+## Deployment
+
+### Install dependencies
+```bash
+npm install
+```
+
+### Build the project
+```bash
+npm run build
+```
+
+### Deploy to AWS
+```bash
+npx cdk deploy
+```
+
+The deployment will output the ARNs of all Lambda functions and DynamoDB table names.
+
+## Useful Commands
+
+* `npm run build`   - Compile TypeScript to JavaScript
+* `npm run watch`   - Watch for changes and compile automatically
+* `npm run test`    - Run Jest unit tests
+* `npx cdk deploy`  - Deploy this stack to your AWS account/region
+* `npx cdk diff`    - Compare deployed stack with current state
+* `npx cdk synth`   - Generate CloudFormation template
+* `npx cdk destroy` - Remove all resources from AWS
+
+## Testing the Saga Pattern
+
+After deployment, invoke the saga orchestrator function with a test payload to see the distributed transaction in action. If any service fails, watch the automatic rollback compensate for completed steps.
+
+## Configuration
+
+The `cdk.json` file tells the CDK Toolkit how to execute your app and includes context values for feature flags and environment settings.

saga-pattern-lambda-durable-functions/saga-pattern-cdk/bin/saga-pattern-cdk.ts

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+#!/usr/bin/env node
+import * as cdk from 'aws-cdk-lib/core';
+import { SagaPatternCdkStack } from '../lib/saga-pattern-cdk-stack';
+
+const app = new cdk.App();
+new SagaPatternCdkStack(app, 'SagaPatternCdkStack', {
+  description: "This templates deploys AWS Lambda Durable Function workflow that implements the SAGA pattern for travel booking use case."
+  /* If you don't specify 'env', this stack will be environment-agnostic.
+   * Account/Region-dependent features and context lookups will not work,
+   * but a single synthesized template can be deployed anywhere. */
+
+  /* Uncomment the next line to specialize this stack for the AWS Account
+   * and Region that are implied by the current CLI configuration. */
+  // env: { account: process.env.CDK_DEFAULT_ACCOUNT, region: process.env.CDK_DEFAULT_REGION },
+
+  /* Uncomment the next line if you know exactly what Account and Region you
+   * want to deploy the stack to. */
+  // env: { account: '123456789012', region: 'us-east-1' },
+
+  /* For more information, see https://docs.aws.amazon.com/cdk/latest/guide/environments.html */
+});

saga-pattern-lambda-durable-functions/saga-pattern-cdk/cdk.json

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+{
+  "app": "npx ts-node --prefer-ts-exts bin/saga-pattern-cdk.ts",
+  "watch": {
+    "include": [
+      "**"
+    ],
+    "exclude": [
+      "README.md",
+      "cdk*.json",
+      "**/*.d.ts",
+      "**/*.js",
+      "tsconfig.json",
+      "package*.json",
+      "yarn.lock",
+      "node_modules",
+      "test"
+    ]
+  },
+  "context": {
+    "@aws-cdk/aws-signer:signingProfileNamePassedToCfn": true,
+    "@aws-cdk/aws-ecs-patterns:secGroupsDisablesImplicitOpenListener": true,
+    "@aws-cdk/aws-lambda:recognizeLayerVersion": true,
+    "@aws-cdk/core:checkSecretUsage": true,
+    "@aws-cdk/core:target-partitions": [
+      "aws",
+      "aws-cn"
+    ],
+    "@aws-cdk-containers/ecs-service-extensions:enableDefaultLogDriver": true,
+    "@aws-cdk/aws-ec2:uniqueImdsv2TemplateName": true,
+    "@aws-cdk/aws-ecs:arnFormatIncludesClusterName": true,
+    "@aws-cdk/aws-iam:minimizePolicies": true,
+    "@aws-cdk/core:validateSnapshotRemovalPolicy": true,
+    "@aws-cdk/aws-codepipeline:crossAccountKeyAliasStackSafeResourceName": true,
+    "@aws-cdk/aws-s3:createDefaultLoggingPolicy": true,
+    "@aws-cdk/aws-sns-subscriptions:restrictSqsDescryption": true,
+    "@aws-cdk/aws-apigateway:disableCloudWatchRole": true,
+    "@aws-cdk/core:enablePartitionLiterals": true,
+    "@aws-cdk/aws-events:eventsTargetQueueSameAccount": true,
+    "@aws-cdk/aws-ecs:disableExplicitDeploymentControllerForCircuitBreaker": true,
+    "@aws-cdk/aws-iam:importedRoleStackSafeDefaultPolicyName": true,
+    "@aws-cdk/aws-s3:serverAccessLogsUseBucketPolicy": true,
+    "@aws-cdk/aws-route53-patters:useCertificate": true,
+    "@aws-cdk/customresources:installLatestAwsSdkDefault": false,
+    "@aws-cdk/aws-rds:databaseProxyUniqueResourceName": true,
+    "@aws-cdk/aws-codedeploy:removeAlarmsFromDeploymentGroup": true,
+    "@aws-cdk/aws-apigateway:authorizerChangeDeploymentLogicalId": true,
+    "@aws-cdk/aws-ec2:launchTemplateDefaultUserData": true,
+    "@aws-cdk/aws-secretsmanager:useAttachedSecretResourcePolicyForSecretTargetAttachments": true,
+    "@aws-cdk/aws-redshift:columnId": true,
+    "@aws-cdk/aws-stepfunctions-tasks:enableEmrServicePolicyV2": true,
+    "@aws-cdk/aws-ec2:restrictDefaultSecurityGroup": true,
+    "@aws-cdk/aws-apigateway:requestValidatorUniqueId": true,
+    "@aws-cdk/aws-kms:aliasNameRef": true,
+    "@aws-cdk/aws-kms:applyImportedAliasPermissionsToPrincipal": true,
+    "@aws-cdk/aws-autoscaling:generateLaunchTemplateInsteadOfLaunchConfig": true,
+    "@aws-cdk/core:includePrefixInUniqueNameGeneration": true,
+    "@aws-cdk/aws-efs:denyAnonymousAccess": true,
+    "@aws-cdk/aws-opensearchservice:enableOpensearchMultiAzWithStandby": true,
+    "@aws-cdk/aws-lambda-nodejs:useLatestRuntimeVersion": true,
+    "@aws-cdk/aws-efs:mountTargetOrderInsensitiveLogicalId": true,
+    "@aws-cdk/aws-rds:auroraClusterChangeScopeOfInstanceParameterGroupWithEachParameters": true,
+    "@aws-cdk/aws-appsync:useArnForSourceApiAssociationIdentifier": true,
+    "@aws-cdk/aws-rds:preventRenderingDeprecatedCredentials": true,
+    "@aws-cdk/aws-codepipeline-actions:useNewDefaultBranchForCodeCommitSource": true,
+    "@aws-cdk/aws-cloudwatch-actions:changeLambdaPermissionLogicalIdForLambdaAction": true,
+    "@aws-cdk/aws-codepipeline:crossAccountKeysDefaultValueToFalse": true,
+    "@aws-cdk/aws-codepipeline:defaultPipelineTypeToV2": true,
+    "@aws-cdk/aws-kms:reduceCrossAccountRegionPolicyScope": true,
+    "@aws-cdk/aws-eks:nodegroupNameAttribute": true,
+    "@aws-cdk/aws-ec2:ebsDefaultGp3Volume": true,
+    "@aws-cdk/aws-ecs:removeDefaultDeploymentAlarm": true,
+    "@aws-cdk/custom-resources:logApiResponseDataPropertyTrueDefault": false,
+    "@aws-cdk/aws-s3:keepNotificationInImportedBucket": false,
+    "@aws-cdk/core:explicitStackTags": true,
+    "@aws-cdk/aws-ecs:enableImdsBlockingDeprecatedFeature": false,
+    "@aws-cdk/aws-ecs:disableEcsImdsBlocking": true,
+    "@aws-cdk/aws-ecs:reduceEc2FargateCloudWatchPermissions": true,
+    "@aws-cdk/aws-dynamodb:resourcePolicyPerReplica": true,
+    "@aws-cdk/aws-ec2:ec2SumTImeoutEnabled": true,
+    "@aws-cdk/aws-appsync:appSyncGraphQLAPIScopeLambdaPermission": true,
+    "@aws-cdk/aws-rds:setCorrectValueForDatabaseInstanceReadReplicaInstanceResourceId": true,
+    "@aws-cdk/core:cfnIncludeRejectComplexResourceUpdateCreatePolicyIntrinsics": true,
+    "@aws-cdk/aws-lambda-nodejs:sdkV3ExcludeSmithyPackages": true,
+    "@aws-cdk/aws-stepfunctions-tasks:fixRunEcsTaskPolicy": true,
+    "@aws-cdk/aws-ec2:bastionHostUseAmazonLinux2023ByDefault": true,
+    "@aws-cdk/aws-route53-targets:userPoolDomainNameMethodWithoutCustomResource": true,
+    "@aws-cdk/aws-elasticloadbalancingV2:albDualstackWithoutPublicIpv4SecurityGroupRulesDefault": true,
+    "@aws-cdk/aws-iam:oidcRejectUnauthorizedConnections": true,
+    "@aws-cdk/core:enableAdditionalMetadataCollection": true,
+    "@aws-cdk/aws-lambda:createNewPoliciesWithAddToRolePolicy": false,
+    "@aws-cdk/aws-s3:setUniqueReplicationRoleName": true,
+    "@aws-cdk/aws-events:requireEventBusPolicySid": true,
+    "@aws-cdk/core:aspectPrioritiesMutating": true,
+    "@aws-cdk/aws-dynamodb:retainTableReplica": true,
+    "@aws-cdk/aws-stepfunctions:useDistributedMapResultWriterV2": true,
+    "@aws-cdk/s3-notifications:addS3TrustKeyPolicyForSnsSubscriptions": true,
+    "@aws-cdk/aws-ec2:requirePrivateSubnetsForEgressOnlyInternetGateway": true,
+    "@aws-cdk/aws-s3:publicAccessBlockedByDefault": true,
+    "@aws-cdk/aws-lambda:useCdkManagedLogGroup": true,
+    "@aws-cdk/aws-elasticloadbalancingv2:networkLoadBalancerWithSecurityGroupByDefault": true,
+    "@aws-cdk/aws-ecs-patterns:uniqueTargetGroupId": true
+  }
+}

saga-pattern-lambda-durable-functions/saga-pattern-cdk/jest.config.js

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+module.exports = {
+  testEnvironment: 'node',
+  roots: ['<rootDir>/test'],
+  testMatch: ['**/*.test.ts'],
+  transform: {
+    '^.+\\.tsx?$': 'ts-jest'
+  },
+  setupFilesAfterEnv: ['aws-cdk-lib/testhelpers/jest-autoclean'],
+};

saga-pattern-lambda-durable-functions/saga-pattern-cdk/lambda/car/cancel_car.py

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+import json
+import os
+from datetime import datetime
+import boto3
+from botocore.exceptions import ClientError
+
+dynamodb = boto3.resource('dynamodb')
+table_name = os.environ.get('TABLE_NAME', 'saga-car-rentals')
+table = dynamodb.Table(table_name)
+
+def lambda_handler(event, context):
+    """
+    Cancel a car rental by updating the status
+    Handles both direct invocation and API Gateway events
+    """
+    try:
+        # Handle different event formats
+        if isinstance(event, str):
+            event = json.loads(event)
+
+        # If event has a 'body' field (API Gateway format), parse it
+        if 'body' in event:
+            body = json.loads(event['body']) if isinstance(event['body'], str) else event['body']
+        else:
+            body = event
+
+        # Extract rental ID from event
+        rental_id = body.get('rentalId')
+
+        if not rental_id:
+            return {
+                'statusCode': 400,
+                'body': json.dumps({
+                    'message': 'rentalId is required'
+                })
+            }
+
+        # Check if rental exists
+        response = table.get_item(Key={'rentalId': rental_id})
+
+        if 'Item' not in response:
+            return {
+                'statusCode': 404,
+                'body': json.dumps({
+                    'message': f'Rental {rental_id} not found'
+                })
+            }
+
+        # Update rental status to CANCELLED
+        table.update_item(
+            Key={'rentalId': rental_id},
+            UpdateExpression='SET #status = :status, updatedAt = :updatedAt',
+            ExpressionAttributeNames={'#status': 'status'},
+            ExpressionAttributeValues={
+                ':status': 'CANCELLED',
+                ':updatedAt': datetime.utcnow().isoformat()
+            }
+        )
+
+        return {
+            'statusCode': 200,
+            'body': json.dumps({
+                'message': 'Car rental cancelled successfully',
+                'rentalId': rental_id,
+                'status': 'CANCELLED'
+            })
+        }
+
+    except ClientError as e:
+        error_msg = f"DynamoDB error: {e.response['Error']['Message']}"
+        print(error_msg)
+        return {
+            'statusCode': 500,
+            'body': json.dumps({
+                'message': 'Failed to cancel car rental',
+                'error': e.response['Error']['Message'],
+                'errorType': 'DynamoDBError'
+            })
+        }
+    except json.JSONDecodeError as e:
+        error_msg = f"JSON parsing error: {str(e)}"
+        print(error_msg)
+        return {
+            'statusCode': 400,
+            'body': json.dumps({
+                'message': 'Invalid JSON in request',
+                'error': str(e),
+                'errorType': 'JSONDecodeError'
+            })
+        }
+    except Exception as e:
+        error_msg = f"Unexpected error: {str(e)}"
+        print(error_msg)
+        return {
+            'statusCode': 500,
+            'body': json.dumps({
+                'message': 'Failed to cancel car rental',
+                'error': str(e),
+                'errorType': type(e).__name__
+            })
+        }