Greengrass_HelloWorld lambda doesn't publish to Amazon IoT console - amazon-web-services

Question

I have been following the documentation in every step, and I didn't face any errors. Configured, deployed and made a subscription to hello/world topic just as the documentation detailed. However, when I arrived at the testing step here: https://docs.aws.amazon.com/greengrass/latest/developerguide/lambda-check.html
No messages were showing up on the IoT console (subscription view hello/world)! I am using Greengrass core daemon which runs on my Ubuntu machine, it is active and listens to port 8000. I don't think there is anything wrong with my local device because the group was deployed successfully and because I see the communications going both ways on Wireshark.
I have these logs on my machine: /home/##/Desktop/greengrass/ggc/var/log/system/runtime.log:
[2019-09-28T06:57:42.492-07:00][INFO]-===========================================
[2019-09-28T06:57:42.492-07:00][INFO]-Greengrass Version: 1.9.3-RC3
[2019-09-28T06:57:42.492-07:00][INFO]-Greengrass Root: /home/##/Desktop/greengrass
[2019-09-28T06:57:42.492-07:00][INFO]-Greengrass Write Directory: /home/##/Desktop/greengrass/ggc
[2019-09-28T06:57:42.492-07:00][INFO]-Group File Directory: /home/##/Desktop/greengrass/ggc/deployment/group
[2019-09-28T06:57:42.492-07:00][INFO]-Default Lambda UID: 122
[2019-09-28T06:57:42.492-07:00][INFO]-Default Lambda GID: 127
[2019-09-28T06:57:42.492-07:00][INFO]-===========================================
[2019-09-28T06:57:42.492-07:00][INFO]-The current core is using the AWS IoT certificates with fingerprint. {"fingerprint": "90##4d"}
[2019-09-28T06:57:42.492-07:00][INFO]-Will persist worker process info. {"dir": "/home/##/Desktop/greengrass/ggc/ggc/core/var/worker/processes"}
[2019-09-28T06:57:42.493-07:00][INFO]-Will persist worker process info. {"dir": "/home/##/Desktop/greengrass/ggc/ggc/core/var/worker/processes"}
[2019-09-28T06:57:42.494-07:00][INFO]-No proxy URL found.
[2019-09-28T06:57:42.495-07:00][INFO]-Started Deployment Agent to listen for updates. [2019-09-28T06:57:42.495-07:00][INFO]-Connecting with MQTT. {"endpoint": "a6##ws-ats.iot.us-east-2.amazonaws.com:8883", "clientId": "simulators_gg_Core"}
[2019-09-28T06:57:42.497-07:00][INFO]-The current core is using the AWS IoT certificates with fingerprint. {"fingerprint": "90##4d"}
[2019-09-28T06:57:42.685-07:00][INFO]-MQTT connection successful. {"attemptId": "GVko", "clientId": "simulators_gg_Core"}
[2019-09-28T06:57:42.685-07:00][INFO]-MQTT connection established. {"endpoint": "a6##ws-ats.iot.us-east-2.amazonaws.com:8883", "clientId": "simulators_gg_Core"}
[2019-09-28T06:57:42.685-07:00][INFO]-MQTT connection connected. Start subscribing. {"clientId": "simulators_gg_Core"}
[2019-09-28T06:57:42.685-07:00][INFO]-Deployment agent connected to cloud.
[2019-09-28T06:57:42.685-07:00][INFO]-Start subscribing. {"numOfTopics": 2, "clientId": "simulators_gg_Core"}
[2019-09-28T06:57:42.685-07:00][INFO]-Trying to subscribe to topic $aws/things/simulators_gg_Core-gda/shadow/update/delta
[2019-09-28T06:57:42.727-07:00][INFO]-Trying to subscribe to topic $aws/things/simulators_gg_Core-gda/shadow/get/accepted
[2019-09-28T06:57:42.814-07:00][INFO]-All topics subscribed. {"clientId": "simulators_gg_Core"}
[2019-09-28T06:58:57.888-07:00][INFO]-Daemon received signal: terminated. [2019-09-28T06:58:57.888-07:00][INFO]-Shutting down daemon.
[2019-09-28T06:58:57.888-07:00][INFO]-Stopping all workers.
[2019-09-28T06:58:57.888-07:00][INFO]-Lifecycle manager is stopped.
[2019-09-28T06:58:57.888-07:00][INFO]-IPC server stopped.
/home/##/Desktop/greengrass/ggc/var/log/system/localwatch/localwatch.log:
[2019-09-28T06:57:42.491-07:00][DEBUG]-will keep the log files for the following lambdas {"readingPath": "/home/##/Desktop/greengrass/ggc/var/log/user", "lambdas": "map[]"}
[2019-09-28T06:57:42.492-07:00][WARN]-failed to list the user log directory {"path": "/home/##/Desktop/greengrass/ggc/var/log/user"}
Thanks in advance.

Answer 1

I had a similar issue on another platform (Jetson Nano). I could not get a response after going through the AWS instructions for setting up a simple Lambda using IOT Greengrass. In my search for answers I discovered that AWS has a qualification test script for any device you connect.
It goes through an automated process of deploying and testing a lambda function(as well as other functionality) and reports results for each step and docs provide troubleshooting info for failures.
By going through those tests I was able to narrow down the issues with my setup, installation, and configuration. The testing docs give pointers to troubleshoot test results. Here is a link to the test: https://docs.aws.amazon.com/greengrass/latest/developerguide/device-tester-for-greengrass-ug.html
If you follow the 'Next Topic' links, it will take you through the complete test. Let me warn you that its extensive, and will take some time, but for me it gave a lot of detailed insight that a hello world does not.