AWS Greengrass
Developer Guide

Verify the Lambda Function Is Running on the Device

From the left pane of the AWS IoT console, choose Test.

                    Screenshot of AWS IoT console with Test highlighted.

In Subscription topic field, type hello/world (don't choose Subscribe to topic yet). For Quality of Service, select 0. For MQTT payload display, select Display payloads as strings (more accurate).

                    Screenshot of Subscriptions.

Next, choose Subscribe to topic.

Assuming the Lambda function is running on your device, it will publish messages to the hello/world topic similar to the following:

                    Screenshot of message sent to the hello/world topic with message


Although the Lambda function running on the AWS Greengrass core device continues to send MQTT messages to the hello/world topic in the AWS IoT cloud, don't stop the AWS Greengrass daemon because the remaining modules assume that it's running.