jvillane / aws-sam-step-functions-lambda

A simple example of a lambda written using TypeScript + Node, coordinated by a Step Functions workflow, that can be initiated and check its status by two API Gateway endpoints using an AWS SAM template

The worst number logic (aka aws-sam-step-functions-lambda)

A simple example that shows the potential of AWS Step Functions using:

• TypeScript + Node for lambda implementation
• TypeScript + Jest for unit testing
• API Gateway + OpenAPI/Swagger integration for API validation
• AWS SAM for infrastructure templating

Requirements

• Node + NPM
• aws-cli (installed and configured)
• aws-sam-cli

Deployment

There's a sh file called deploy.sh meant to be used for infrastructure creating/updating:

sh deploy.sh <STACK_NAME> <S3_BUCKET>

Where:

• STACK_NAME is the name of the stack
• S3_BUCKET refers to an existing S3 bucket where the OpenAPI definition is going to be upload

The Workflow

It's a very simple and numeric logic that is represented by the workflow:

RandomNumber

It generates a random number between 1 and 15.

If the number is 13 (unlucky thirteen) the step retry 2 times, and if there's the bad luck of getting the '13' three times in a row, the workflow unsuccessfully ends.

The result number is passed to the Revision task.

Revision

If the number is 7 (lucky seven) the workflow successfully ends.

If the number is different from 7 or 13, the result number is passed to the task Init.

Init

It builds an array with length n equals to 'number': [0, 1, ... n] and generates a Map task with that array.

Execute

It generates a new number equals to the argument number or plus/minus 1.

It prints on the console the 2 values.

WaitPlz

It stops the process for 2 seconds.

End

It calculates the sum of all the Map executions.

API endpoints

Execution start

The exposed endpoint is POST to random-workflow/ path. The body of the request is passed as an input to the workflow execution.

The response includes the execution identificator for the status request:

{
  "executionId": "<EXECUTION_ID>"
}

Execution status

The exposed endpoint is GET to random-workflow/<EXECUTION_ID> path.

The response content is:

{
  "status": "<EXECUTION_STATUS>",
  "output": <EXECUTION_OUTPUT>
}

Where EXECUTION_OUTPUT is present when status is SUCCEED and it's an object with the result of the execution.