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| # Amazon DynamoDB Cross-Account Replication with Global Tables | ||
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| This pattern deploys a DynamoDB Global Table with cross-account replication and an IAM role for secure cross-account read access. | ||
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| Learn more about this pattern at Serverless Land Patterns: https://serverlessland.com/patterns/dynamodb-cross-account-replication-cdk | ||
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| Important: this application uses various AWS services and there are costs associated with these services after the Free Tier usage - please see the [AWS Pricing page](https://aws.amazon.com/pricing/) for details. | ||
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| ## Requirements | ||
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| * [AWS CLI](https://docs.aws.amazon.com/cli/latest/userguide/install-cliv2.html) installed and configured | ||
| * [AWS CDK](https://docs.aws.amazon.com/cdk/latest/guide/cli.html) installed | ||
| * [Node.js](https://nodejs.org/en/download/) installed | ||
| * Two AWS accounts (source and replica) | ||
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| ## Deployment Instructions | ||
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| 1. Clone and navigate to the pattern: | ||
| ``` | ||
| cd serverless-patterns/dynamodb-cross-account-replication-cdk | ||
| npm install | ||
| ``` | ||
| 2. Deploy with the replica account ID: | ||
| ``` | ||
| cdk deploy --parameters ReplicaAccountId=123456789012 --parameters ReplicaRegion=us-west-2 | ||
| ``` | ||
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Contributor
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There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Good catch. TableV2 doesn't accept tokens for replica regions (throws ReplicaTableRegionCannotBeToken), so CfnParameter won't work here. Switched to CDK context (-c replicaRegion=us-west-2) which resolves at synth time. README updated to match. |
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| ## How it works | ||
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| - A DynamoDB Global Table is created with a replica in the specified region | ||
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Contributor
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Use "Amazon DynamoDB" on first body reference. The title correctly uses "Amazon DynamoDB"; the first body paragraph and the "How it works" bullet immediately drop to "DynamoDB Global Table". Per AWS naming guidance the first body reference should re-introduce the full service name.
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There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Fixed -- first body reference now uses "Amazon DynamoDB Global Table". |
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| - DynamoDB automatically replicates all writes to the replica with sub-second latency | ||
| - A cross-account IAM role allows the replica account to assume and read from the table | ||
| - Point-in-time recovery is enabled for data protection | ||
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| ## Testing | ||
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Contributor
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. No cross-account read test in the Testing section. The current Testing section only shows reads from the same account. The pattern's headline value is cross-account read, so please demonstrate it.
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There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Fair -- added a cross-account read example using sts assume-role in the Testing section. |
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| ```bash | ||
| # Write an item to the source table | ||
| aws dynamodb put-item --table-name $(aws cloudformation describe-stacks \ | ||
| --stack-name DynamodbCrossAccountReplicationStack \ | ||
| --query 'Stacks[0].Outputs[?OutputKey==`TableName`].OutputValue' --output text) \ | ||
| --item '{"PK":{"S":"user#123"},"SK":{"S":"profile"},"name":{"S":"test"}}' | ||
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| # Read from replica region (same account) | ||
| aws dynamodb get-item --table-name <TableName> \ | ||
| --key '{"PK":{"S":"user#123"},"SK":{"S":"profile"}}' \ | ||
| --region us-west-2 | ||
| ``` | ||
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| ## Cleanup | ||
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| ``` | ||
| cdk destroy | ||
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Contributor
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Cleanup must warn that
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There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Good call -- added a warning note in the Cleanup section about data deletion with RemovalPolicy.DESTROY. |
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| ``` | ||
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| --- | ||
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| Copyright 2026 Amazon.com, Inc. or its affiliates. All Rights Reserved. | ||
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| SPDX-License-Identifier: MIT-0 | ||
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| #!/usr/bin/env node | ||
| import 'source-map-support/register'; | ||
| import * as cdk from 'aws-cdk-lib'; | ||
| import { DynamodbCrossAccountReplicationStack } from '../lib/dynamodb-cross-account-replication-stack'; | ||
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| const app = new cdk.App(); | ||
| new DynamodbCrossAccountReplicationStack(app, 'DynamodbCrossAccountReplicationStack', { | ||
| env: { | ||
| account: process.env.CDK_DEFAULT_ACCOUNT || '123456789012', | ||
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Contributor
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Hardcoded fallback account
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Author
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Fixed -- app.ts now throws with a clear error message if CDK_DEFAULT_ACCOUNT is unset. No more silent fallback to a placeholder. |
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| region: process.env.CDK_DEFAULT_REGION || 'us-east-1', | ||
| }, | ||
| }); | ||
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| { | ||
| "app": "npx ts-node --prefer-ts-exts bin/app.ts" | ||
| } |
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| { | ||
| "title": "Amazon DynamoDB Cross-Account Replication with Global Tables", | ||
| "description": "Deploy a DynamoDB Global Table with cross-account replication and IAM role for secure cross-account read access.", | ||
| "language": "TypeScript", | ||
| "level": "300", | ||
| "framework": "CDK", | ||
| "introBox": { | ||
| "headline": "How it works", | ||
| "text": [ | ||
| "This pattern creates a DynamoDB Global Table that replicates data across AWS accounts and regions.", | ||
| "A cross-account IAM role enables the replica account to read from the table securely.", | ||
| "DynamoDB handles replication automatically with sub-second latency between regions.", | ||
| "Point-in-time recovery is enabled for data protection." | ||
| ] | ||
| }, | ||
| "gitHub": { | ||
| "template": { | ||
| "repoURL": "https://github.com/aws-samples/serverless-patterns/tree/main/dynamodb-cross-account-replication-cdk", | ||
| "templateURL": "serverless-patterns/dynamodb-cross-account-replication-cdk", | ||
| "projectFolder": "dynamodb-cross-account-replication-cdk", | ||
| "templateFile": "lib/dynamodb-cross-account-replication-stack.ts" | ||
| } | ||
| }, | ||
| "resources": { | ||
| "bullets": [ | ||
| { "text": "DynamoDB Global Tables Cross-Account Replication", "link": "https://aws.amazon.com/blogs/database/amazon-dynamodb-global-tables-now-support-replication-across-aws-accounts/" }, | ||
| { "text": "DynamoDB Global Tables Documentation", "link": "https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/GlobalTables.html" } | ||
| ] | ||
| }, | ||
| "deploy": { "text": ["cdk deploy --parameters ReplicaAccountId=123456789012"] }, | ||
| "testing": { "text": ["See the README for testing instructions."] }, | ||
| "cleanup": { "text": ["cdk destroy"] }, | ||
| "authors": [ | ||
| { | ||
| "name": "Nithin Chandran R", | ||
| "bio": "Technical Account Manager at AWS, passionate about serverless and AI/ML.", | ||
| "linkedin": "nithin-chandran-r" | ||
| } | ||
| ] | ||
| } |
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| import * as cdk from 'aws-cdk-lib'; | ||
| import * as dynamodb from 'aws-cdk-lib/aws-dynamodb'; | ||
| import * as iam from 'aws-cdk-lib/aws-iam'; | ||
| import { Construct } from 'constructs'; | ||
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| export class DynamodbCrossAccountReplicationStack extends cdk.Stack { | ||
| constructor(scope: Construct, id: string, props?: cdk.StackProps) { | ||
| super(scope, id, props); | ||
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| const replicaAccountId = new cdk.CfnParameter(this, 'ReplicaAccountId', { | ||
| type: 'String', | ||
| description: 'AWS Account ID for the replica table', | ||
| }); | ||
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| const table = new dynamodb.TableV2(this, 'SourceTable', { | ||
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Contributor
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. KMS expectations for cross-account reads are not addressed.
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Author
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. The table uses the default AWS-owned key (no explicit KMS config), so cross-account reads work without any key policy changes. Added a note in the README that if customers switch to CMK encryption they'll need to grant kms:Decrypt to the cross-account role. |
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| partitionKey: { name: 'PK', type: dynamodb.AttributeType.STRING }, | ||
| sortKey: { name: 'SK', type: dynamodb.AttributeType.STRING }, | ||
| billing: dynamodb.Billing.onDemand(), | ||
| pointInTimeRecovery: true, | ||
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There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. You may want to refer and use
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Author
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Already using pointInTimeRecoverySpecification in the latest commit -- the deprecated pointInTimeRecovery was from an earlier version. |
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| removalPolicy: cdk.RemovalPolicy.DESTROY, | ||
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Contributor
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. The pattern frames itself as a cross-account replication solution and turns on PITR, both signal a production lean. Pairing that with
Contributor
Author
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Fair point. Added inline comment in code explaining DESTROY is for sample pattern testability. Cleanup section already warns about data deletion. Kept DESTROY since RETAIN would leave orphaned tables for users just trying the pattern. |
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| replicas: [ | ||
| { | ||
| region: 'us-west-2', | ||
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Contributor
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Replica region
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Author
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. It's a CDK context value with us-west-2 as fallback (not a string literal baked into logic). Users override via -c replicaRegion=eu-west-1. The fallback is intentional so the pattern works out-of-the-box for quick testing. |
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| }, | ||
| ], | ||
| }); | ||
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There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Title says "cross-account replication" but the implementation is same-account, multi-region. Possible ways to resolve:
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There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Agreed -- reframed the whole pattern. Title is now "DynamoDB Global Tables with Cross-Account Read Access", README explicitly calls out that replication is same-account and the cross-account piece is the IAM role. |
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| // IAM role for cross-account access to the replica | ||
| const crossAccountRole = new iam.Role(this, 'CrossAccountReplicaRole', { | ||
| assumedBy: new iam.AccountPrincipal(replicaAccountId.valueAsString), | ||
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Contributor
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Trust policy allows any principal in the replica account; no
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There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. True -- it trusts the entire account. For a sample pattern this keeps it simple. Adding ExternalId or role-name conditions would make it more production-ready but also more complex to demo. Happy to add an ExternalId condition if you feel strongly about it. |
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| description: 'Allows replica account to read from the global table replica', | ||
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There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Same as above -- Scan dropped. |
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| }); | ||
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| crossAccountRole.addToPolicy(new iam.PolicyStatement({ | ||
| actions: [ | ||
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Contributor
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Cross-account read role cannot access the replica region
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There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. You're right -- table.tableArn is source-region-scoped. Fixed by adding explicit replica region ARNs to the policy so the reader account can access the table in both regions. |
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| 'dynamodb:GetItem', | ||
| 'dynamodb:Query', | ||
| 'dynamodb:Scan', | ||
| 'dynamodb:BatchGetItem', | ||
| ], | ||
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There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Good point -- dropped Scan. GetItem, Query, and BatchGetItem cover the typical cross-account read use cases. |
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| resources: [ | ||
| table.tableArn, | ||
| `${table.tableArn}/index/*`, | ||
| ], | ||
| })); | ||
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| new cdk.CfnOutput(this, 'TableName', { value: table.tableName }); | ||
| new cdk.CfnOutput(this, 'TableArn', { value: table.tableArn }); | ||
| new cdk.CfnOutput(this, 'CrossAccountRoleArn', { value: crossAccountRole.roleArn }); | ||
| new cdk.CfnOutput(this, 'ReplicaRegion', { value: 'us-west-2' }); | ||
| } | ||
| } | ||
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| { | ||
| "name": "dynamodb-cross-account-replication-cdk", | ||
| "version": "1.0.0", | ||
| "bin": { "app": "bin/app.ts" }, | ||
| "scripts": { "build": "tsc", "cdk": "cdk" }, | ||
| "dependencies": { | ||
| "aws-cdk-lib": "^2.180.0", | ||
| "constructs": "^10.0.0", | ||
| "source-map-support": "^0.5.21" | ||
| }, | ||
| "devDependencies": { | ||
| "typescript": "~5.4.0", | ||
| "ts-node": "^10.9.0", | ||
| "@types/node": "^20.0.0" | ||
| } | ||
| } |
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| { | ||
| "compilerOptions": { | ||
| "target": "ES2020", "module": "commonjs", "lib": ["es2020"], | ||
| "declaration": true, "strict": true, "outDir": "build", | ||
| "rootDir": ".", "skipLibCheck": true, "forceConsistentCasingInFileNames": true | ||
| }, | ||
| "exclude": ["node_modules", "build"] | ||
| } |
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cdk bootstrapis missing from Requirements. New users may hit AWS CDK bootstrap errors immediately.There was a problem hiding this comment.
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Added to requirements. Thanks.