DynamoDB Stream is closed if update to streamViewType

[fossamagna]

Environment information

System:
  OS: Linux 6.6 Debian GNU/Linux 11 (bullseye) 11 (bullseye)
  CPU: (8) arm64 unknown
  Memory: 18.98 GB / 23.43 GB
  Shell: /bin/bash
Binaries:
  Node: 22.16.0 - /usr/local/bin/node
  Yarn: 1.22.22 - /usr/local/bin/yarn
  npm: 10.9.2 - /usr/local/bin/npm
  pnpm: undefined - undefined
NPM Packages:
  @aws-amplify/auth-construct: 1.10.0
  @aws-amplify/backend: 1.19.0
  @aws-amplify/backend-ai: Not Found
  @aws-amplify/backend-auth: 1.9.0
  @aws-amplify/backend-cli: 1.8.0
  @aws-amplify/backend-data: 1.6.2
  @aws-amplify/backend-deployer: 2.1.3
  @aws-amplify/backend-function: 1.15.2
  @aws-amplify/backend-output-storage: 1.3.2
  @aws-amplify/backend-secret: 1.4.2
  @aws-amplify/backend-storage: 1.4.2
  @aws-amplify/cli-core: 2.2.1
  @aws-amplify/client-config: 1.9.1
  @aws-amplify/data-construct: 1.16.3
  @aws-amplify/data-schema: 1.21.0
  @aws-amplify/deployed-backend-client: 1.8.1
  @aws-amplify/form-generator: 1.2.1
  @aws-amplify/model-generator: 1.2.2
  @aws-amplify/platform-core: 1.10.3
  @aws-amplify/plugin-types: 1.11.1
  @aws-amplify/sandbox: 2.1.2
  @aws-amplify/schema-generator: 1.4.0
  @aws-cdk/toolkit-lib: 1.1.1
  aws-amplify: 6.15.3
  aws-cdk-lib: 2.189.1
  typescript: 5.8.3
No AWS environment variables
No CDK environment variables

Data packages

/workspaces/stream-is-closed
├─┬ @aws-amplify/backend-cli@1.8.0
│ └─┬ @aws-amplify/schema-generator@1.4.0
│   └── @aws-amplify/graphql-schema-generator@0.11.12
└─┬ @aws-amplify/backend@1.19.0
  └─┬ @aws-amplify/backend-data@1.6.2
    └── @aws-amplify/data-construct@1.16.3

Description

Steps to Reproduce

1. Set up DynamoDB Streams following the Amplify Docs DynamoDB Streams documentation.
2. Run npx ampx sandbox to deploy
3. Add to backend.ts following code and save.

   backend.data.resources.cfnResources.amplifyDynamoDbTables["Todo"].streamSpecification = {
     streamViewType: StreamViewType.NEW_IMAGE,
   };

4. Wait for deployed
5. The DynamoDB Stream trigger for Lambda is disabled
   
6. The ARN for the Latest Stream on the DynamoDB page does not match the ARN for the Event source mapping in the Lambda Trigger
   
7. The Stream ARN in CloudFormation Outputs remains the same as the Lambda Trigger and is still outdated.
   

[pahud]

Hi @fossamagna,

Thank you for reporting this issue with detailed reproduction steps and screenshots — and even more so for submitting PR #3387 to fix it! 🎉

Your analysis is spot-on: when streamSpecification is updated, DynamoDB creates a new stream with a new ARN, but the TableManager Lambda was returning the stale ARN from the initial describeTable call.

Your fix to re-fetch the table state after the stream update ensures the latest LatestStreamArn is returned to CloudFormation, which will then propagate to the Lambda event source mapping correctly.

The PR looks good to me. The team will get it reviewed when it's ready.