**Overview**

In AWS it is possible to trigger step functions through an API Gateway integration, see https://docs.aws.amazon.com/step-functions/latest/dg/tutorial-api-gateway.html

Similar integrations already occur within localstack, however the step function URIs are notably missing. See lines 66-88 of https://github.com/localstack/localstack/blob/master/localstack/services/apigateway/apigateway_listener.py



┆Issue is synchronized with this [Jira Bug](https://localstack.atlassian.net/browse/LOC-107) by [Unito](https://www.unito.io/learn-more)

api_id = self.create_api_gateway_and_deploy({})
        url = gateway_request_url(api_id=api_id, stage_name='staging', path='/')
        response = requests.put(
            url,
            json.dumps({'id': 'id1', 'data': 'foobar123'}),
        )
        self.assertEqual(response.status_code, 404)
    def test_put_integration_dynamodb_proxy_validation_with_response_template(self):
        response_templates = {'application/json': json.dumps({'TableName': 'MusicCollection',
                                         'Item': {'id': '$.Id', 'data': '$.data'}})}
        api_id = self.create_api_gateway_and_deploy(response_templates)
        url = gateway_request_url(api_id=api_id, stage_name='staging', path='/')
        response = requests.put(
            url,
            json.dumps({'id': 'id1', 'data': 'foobar123'}),
        )
        self.assertEqual(response.status_code, 200)
        dynamo_client = aws_stack.connect_to_resource('dynamodb')
        table = dynamo_client.Table('MusicCollection')
        result = table.get_item(Key={'id': 'id1'})
        self.assertEqual(result['Item']['data'], 'foobar123')
    def test_api_key_required_for_methods(self):