# A Step Functions Standard Workflow doing PUT and GET ITEM operations directly on DynamoDb 

The SAM template deploys a Step Functions workflow, that takes in a payload and puts the item in DynamoBb. Additionally, this workflow also shows how to read an item directly from the DynamoDB table. The SAM template contains the minimum IAM resources required to run the application.

Learn more about this pattern at Serverless Land Patterns: https://serverlessland.com/patterns/sfn-dynamodb

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
    ```
2. Change directory to the pattern directory:
    ```
    cd sfn-dynamodb
    ```
3. 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
    ```
4. 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.

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

## How it works

* Start the Step Function execution with the sample event payload 
* As part of the execution, part of the payload (the `message` attribute of the payload) gets pushed to the queue
* Run the cli command to pull messages from the queue to verify if the message got delivered.

## Testing

Run the following AWS CLI command to send a 'start-execution` command to start the Step Functions workflow. Note, you must edit the {StateMachineExpressSynctoLambda} placeholder with the ARN of the deployed Step Functions workflow. This is provided in the stack outputs.

```bash
aws stepfunctions start-execution  --name "test" --state-machine-arn "{StateMachinetoDDBArn}" --input "{\"id\":  \"12345\" }"
```

### output:

```bash
{
    "executionArn": "arn:aws:states:us-east-1:123456789012:execution:MyStateMachine-LIXV3ls6HtnY:test",
    "startDate": 1620244153.977
}
```

Note the `executionArn` from the above output and run the below cli command to get the status of the execution

```bash
aws stepfunctions describe-execution --execution-arn  "{executionArn}"
```

### Get execution status output:

```bash
{
    "executionArn": "arn:aws:states:us-east-1:826849495443:execution:StateMachinetoDDB-AiwwYeLJk2AL:test",
    "stateMachineArn": "arn:aws:states:us-east-1:826849495443:stateMachine:StateMachinetoDDB-AiwwYeLJk2AL",
    "name": "test",
    "status": "SUCCEEDED",
    "startDate": 1620674586.347,
    "stopDate": 1620674586.553,
    "input": "{\"id\":  \"123456\" }",
    "inputDetails": {
        "included": true
    },
    "output": "{\"description\":{\"S\":\"Hello, my id is 123456.\"},\"id\":{\"S\":\"123456\"}}",
    "outputDetails": {
        "included": true
    }
}
```
Once the `status` is `SUCCEEDED`, you can verify what was stored in DynamoDB table by looking at the "output" attribute.
Additionally, you can also verify if the item is stored in DynamoDB by running the below get item cli command on the table.

```bash
 aws dynamodb get-item --table-name my-table --key "{\"id\": {\"S\": \"12345\"} }"
```

### DynamoDB Get Item Output:

```bash
{
    "Item": {
        "id": {
            "S": "1234"
        },
        "description": {
            "S": "Hello, my id is 1234"
        }
    }
}
```

## 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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