cfn-dynamodb-streamspecification

Purpose

AWS CloudFormation does not support AWS DynamoDB Streams (StreamSpecifications). This is a Lambda-backed custom resource to add AWS DynamoDB's Streams to CloudFormation.

This package on NPM
This package on GitHub

Implementation

This Lambda makes use of the Lambda-Backed CloudFormation Custom Resource flow module, cfn-lambda (GitHub / NPM).

Usage

See ./example.template.json for a sample CloudFormation template. The example uses Condition statements, Parameters, and dynamic ServiceToken generation fully.

"StreamSpecificationLogicalIdInResourcesObject": {
  "Type": "Type": "Custom::DynamoDBStreamSpecification",
  "Properties": {
    "ServiceToken": "arn:aws:lambda:<cfn-region-id>:<your-account-id>:function:<this-deployed-lambda-name>",
    "TableName": { "Ref": "MyDynamoDBTable" }, // REQUIRED
    "StreamViewType": "NEW_IMAGE"             // REQUIRED enum (line below)
      // Values: NEW_IMAGE | OLD_IMAGE | NEW_AND_OLD_IMAGES | KEYS_ONLY
    }
  }
}

`Ref` and `Fn::GetAtt`

Ref does not return the ARN, it returns the <table>::<viewType> and is used internally for state management on UPDATE actions.

Fn::GetAtt has one property, Arn. This returns the table's LatestStreamArn.

Installation of the Resource Service Lambda

Using the Provided Instant Install Script

The way that takes 10 seconds...

# Have aws CLI installed + permissions for IAM and Lamdba
$ npm run cfn-lambda-deploy

You will have this resource installed in every supported Region globally!

Using the AWS Console

... And the way more difficult way.

IMPORTANT: With this method, you must install this custom service Lambda in each AWS Region in which you want CloudFormation to be able to access the DynamoDBStreamSpecification custom resource!

Go to the AWS Lambda Console Create Function view:

Zip this repository into /tmp/DynamoDBStreamSpecification.zip

$ cd $REPO_ROOT && zip -r /tmp/DynamoDBStreamSpecification.zip;
Enter a name in the Name blank. I suggest: CfnLambdaResouce-DynamoDBStreamSpecification
Enter a Description (optional).
Toggle Code Entry Type to "Upload a .ZIP file"
Click "Upload", navigate to and select /tmp/DynamoDBStreamSpecification.zip
Set the Timeout under Advanced Settings to 10 sec
Click the Role dropdown then click "Basic Execution Role". This will pop out a new window.
Select IAM Role, then select option "Create a new IAM Role"
Name the role lambda_cfn_api_gateway_deployment (or something descriptive)
Click "View Policy Document", click "Edit" on the right, then hit "OK"
Copy and paste the ./execution-policy.json document.
Hit "Allow". The window will close. Go back to the first window if you are not already there.
Click "Create Function". Finally, done! Now go to Usage or see the example template. Next time, stick to the instant deploy script.

Miscellaneous

Collaboration & Requests

Submit pull requests or Tweet to one us (Andrew @ayetempleton / Alex @omgnvm) if you want to get involved with roadmap as well, or if you want to do this for a living :)

License

MIT

Want More CloudFormation Custom Resources?

Work is (extremely) active by our contributors, published here:
Andrew Templetons's NPM Account
Alex Jestin Taylor's NPM Account

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