Push/publish events on Step Functions state transition

Question

I'd like to notify an external observer (a client web app in my current case, but interested in other use cases too) of status updates when a Step Functions-orchestrated workflow progresses - in an event-driven way rather than by polling the execution history API.

Accepted Answer

I tested out approach using CloudWatch and it works. I enabled CloudWatch logging, it logs event TaskStateEntered on start and TaskStateExited on exit. You can create filter on log like { $.type="TaskStateExited"}

Sample CloudWatch log entry

```
{
    "id": "6",
    "type": "TaskStateExited",
    "details": {
        "name": "State1",
        "output": "{"who":"amit","taskresult":{"statusCode":200,"body":"\"hello from amit\""}}"
    },
    "previous_event_id": "5",
    "event_timestamp": "1593780767604",
    "execution_arn": "arn:aws:states:us-east-1:xxx:execution:MyStateMachine:fa8cfe8f-492d-7e27-7492-6aa20f12fe18"
}

Push/publish events on Step Functions state transition

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