Medium: AWS Step Function handler (https://dev.to/wparad/aws-step-functions-advanced-30k2)

stepFunctionHandler.js

async onEvent(trigger) {
    logger.log({ title: 'Starting new Triggered work', level: 'INFO', trigger });

    if (trigger.context && trigger.context.StateMachine) {
      const processorId =
            `${trigger.context.StateMachine.Name}|${trigger.context.State.Name}`;
      const payload = trigger.context.Execution.Input;
      const parameters = trigger.parameters;
      const context = trigger.context.State;
      const processors = {
        'StepFunctionName|Start': () => handler.start(payload, parameters, context),
        'StepFunctionName|Verify': () => handler.verify(payload, parameters, context),
        'StepFunctionName|Cleanup': () => handler.cleanup(payload, parameters, context)
      };

      if (!processors[processorId]) {
        logger.log({ title: 'Step Function processor does not exist for type',
          level: 'ERROR', trigger, payload, stepFunctionContext });
        return {};
      }

      try {
        const result = await processors[processorId]();
        return result;
      } catch (error) {
        if (error.code !== 'ForceRetryExecution'
            && error.message !== 'ForceRetryExecution') {
          logger.log({ title: 'Error handling StepFunction trigger',
            level: 'CRITICAL', error, trigger, payload, stepFunctionContext });
        }

        if (stepFunctionContext && stepFunctionContext.RetryCount > 10) {
          logger.log({ title: 'Too many retries, log as ERROR.',
            level: 'ERROR', error, trigger, payload, stepFunctionContext });
        }
        throw error;
      }
    }
  // Handle other types ...
}