# AWS DynamoDB Streams to Event Bridge

The SAM template deploys a DynamoDB Streams to capture changed data and push to EventBridge routing rules.

This version is a Java port of the [original pattern](https://serverlessland.com/patterns/dynamodb-lambda-eventbridge).

When new items are added, updated or deleted on the DynamoDB table, the item-level changes in the table will be streamed to EventBridge bus where given routing rules for different types of changes are applied. 

For example, insert events and deleted events are routed to different targets by EventBridge rules.

Learn more about this pattern at Serverless Land Patterns: << Add the live URL here >>

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. You are responsible for any AWS costs incurred. No warranty is implied in this example.

## Requirements

* [Create an AWS account](https://portal.aws.amazon.com/gp/aws/developer/registration/index.html) if you do not already have one and log in. The IAM user that you use must have sufficient permissions to make necessary AWS service calls and manage AWS resources.
* [AWS CLI](https://docs.aws.amazon.com/cli/latest/userguide/install-cliv2.html) installed and configured
* [Git Installed](https://git-scm.com/book/en/v2/Getting-Started-Installing-Git)
* [AWS Serverless Application Model](https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/serverless-sam-cli-install.html) (AWS SAM) installed

## Deployment Instructions

1. Create a new directory, navigate to that directory in a terminal and clone the GitHub repository:
    ``` 
    git clone https://github.com/aws-samples/serverless-patterns
    ```
1. Change directory to the pattern directory:
    ```
    cd dynamodb-eventbridge-java
    ```
1. From the command line, use AWS SAM to deploy the AWS resources for the pattern as specified in the template.yml file:
    ```
    sam deploy --guided
    ```
1. During the prompts:
    * Enter a stack name
    * Enter the desired AWS Region
    * Allow SAM CLI to create IAM roles with the required permissions.

    Once you have run `sam deploy --guided` mode once and saved arguments to a configuration file (samconfig.toml), you can use `sam deploy` in future to use these defaults.

1. Note the outputs from the SAM deployment process. These contain the resource names and/or ARNs which are used for testing.

## How it works

When new items are added to the DynamoDB table, a payload with item-level changes will sent to the Event Bridge bus. The two rules on the bus, then trigger a lambda depending on whether it was an insert or remove event. 

## Testing

* After deployment is complete, add an item to the DynamoDB table and check status of lambda processing function through Exports and streams tab on table details console.

* For logs of Lambda processing function, check on CloudWatch Logs with pattern "EventProcessingFunction". When an event is inserted into the table, the function will process an event like:
```
{
    "eventSourceARN": "<DynamoDB Event Stream ARN>",
    "eventID": "3f402e752ba49c68255905249c8c9201",
    "eventName": "INSERT",
    "eventVersion": "1.1",
    "eventSource": "aws:dynamodb",
    "awsRegion": "ap-southeast-2",
    "dynamodb": {
        "approximateCreationDateTime": "Apr 9, 2022, 6:58:28 AM",
        "keys": {
            "name": {
                "s": "Victoria"
            }
        },
        "newImage": {
            "name": {
                "s": "Victoria"
            }
        },
        "sequenceNumber": "100000000008371389299",
        "sizeBytes": 24,
        "streamViewType": "NEW_AND_OLD_IMAGES"
    }
}
```

* For logs of Insert events on DynamoDB Stream, check on CloudWatch Logs with pattern "SubscribeInsertFunction".

* For logs of Insert events on DynamoDB Stream, check on CloudWatch Logs with pattern "SubscribeRemoveFunction".

## Cleanup
 
1. Delete the stack
    ```bash
    aws cloudformation delete-stack --stack-name STACK_NAME
    ```
1. Confirm the stack has been deleted
    ```bash
    aws cloudformation list-stacks --query "StackSummaries[?contains(StackName,'STACK_NAME')].StackStatus"
    ```
----
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