How to clear topic with malformed JSON payload?

Question

I made a silly mistake and triggered a lambda on my core device with an malformed JSON payload.  
  
Now greengrass is stuck in a loop,  It tries to trigger the lambda, but the JSON payload cannot be loaded, so it fails and the lambda  is not called, and, therefore, the message is never ack'ed... so it wait for timeout an tries again.  
  
Now, reboot (restarting Greengrass probably too) will clear the situation, but is there a better way?   
  
Cheers,  
    François

Answer

Hi Rob,  
Thanks for answering.  
  
I no longer have those logs. I reflashed that device.  
  
From the logs I saw, this is what I understand was happening   
     - The lambda manager picks up a message with a triggering topic  
     - The lambda manager tries to decode the payload as JSON.  
     - An exception is raised because the JSON is not correct  
     - The lambda manager bails out without calling the lambda  
     - The lambda not being called, the message remains on the queue  
     - After some timeout, the same message is picked up and the process starts again.   
  
There was an error message about JSON being invalid in the greengrass.log file  
  
Cheers

Answer

Hello François,  
  
Is it failing to even call your lambda function handler?   
In V2, the lambda manager logs into `greengrass.log` as it is a plugin into the Nucleus.  
Can you provide an excerpt from the log showing the error?  
If there is an error in your lambda's log file that would also be helpful to investigate.  
  
Edited by: rob-aws on Sep 14, 2021 9:17 AM

Answer

Closing this thing  
  
Just make sure the JSON is correct ;)

How to clear topic with malformed JSON payload?

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