HowTo: NodeRed – Automatic saving of the NodeRed journal after starting NodeRed (for debugging purposes)

I recently had a problem with NodeRed that caused the NodeRed process to crash sometimes.

Not really that bad because it is restarted automatically. On the other hand, it annoyed me at some point because the data in the dashboard view was lost and status messages were sent every time.

So it was time to get to the bottom of it. First I checked the journal of the NodeRed service vai “sudo journal -f -u nodered”.

This command shows all status messages that are stored in the journal of the service. I was actually only interested in the last messages before NodeRed was restarted.

For this purpose, I created the flow shown below. Each time after the restart of NodeRed, this saves the contents of the journal in the folder “/home/pi/nodeRedLogFiles”.

If you are looking for an error that leads to a restart, you should find it quickly thanks to this. 🙂

Safety instructions

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Helpful Articles:
So that you can install new nodes, NodeRed should of course already be installed.
How to prepare a RaspberryPi and then install NodeRed on it is described in the following articles.

RaspberryPi – Setup for nerdiys!
RaspberryPi – The first configuration!

RaspberryPi – Control the RaspberryPi via SSH
NodeRed – Installation of NodeRed on the RaspberryPi

Required tools:

Required material:

In the following list you will find all the parts you need to implement this article.

Log in to the NodeRed configuration interface

Before you can edit your NodeRed configuration you must - if activated - first log in to the NodeRed configuration interface.

View of the login screen. Here you have to enter the login details that you entered during the configuration of the login. Information about this can be found in the article NodeRed - User Login Setup.

Import node code

To test this code, you can simply import the code below into your NodeRed installation. You can find tips on this in the article NodeRed – Importing and exporting node code.

View of the NodeRed flow in the NodeRed configuration view.
[{"id":"185f8c16.a86d64","type":"exec","z":"2dcf0cc0.aeb894","command":"journalctl -u nodered -all","addpay":false,"append":"","useSpawn":"true","timer":"","oldrc":false,"name":"last","x":410,"y":3480,"wires":[["30e6e36b.45d3fc"],[],[]]},{"id":"30e6e36b.45d3fc","type":"function","z":"2dcf0cc0.aeb894","name":"prepare filename","func":"\nvar d = new Date();\nvar t = d.getTime();\nvar year = d.getFullYear();\nvar month = d.getMonth()+1; \nvar day = d.getDate();\nvar hour  = d.getHours();\nvar minute  = d.getMinutes();\n\nif(month.toString().length == 1) \n{\n    month = '0'+month;\n}\n\nmsg.filename = \"/home/pi/nodeRedLogFiles/nodeRedLog_\"+day+\"-\"+month+\"-\"+year+\"-\"+hour+\":\"+minute+\".csv\";\n\nreturn msg;","outputs":1,"noerr":0,"x":610,"y":3480,"wires":[["9f916f6c.d00cb"]]},{"id":"519cb1ab.0032b","type":"inject","z":"2dcf0cc0.aeb894","name":"save last nodered-journal","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":true,"onceDelay":0.1,"x":210,"y":3480,"wires":[["185f8c16.a86d64"]]},{"id":"9f916f6c.d00cb","type":"file","z":"2dcf0cc0.aeb894","name":"","filename":"","appendNewline":true,"createDir":true,"overwriteFile":"false","encoding":"none","x":810,"y":3480,"wires":[[]]},{"id":"510d4143.de0cb","type":"comment","z":"2dcf0cc0.aeb894","name":"Save last journal nodered","info":"","x":170,"y":3420,"wires":[]}]

View in the dashboard

View of the collected NodeRed journals

In the folder “/home/pi/nodeRedLogFiles” on your RaspberryPi you will find the saved NodeRed logs that are saved after every restart of NodeRed.

View of the saved NodeRed log files.

I hope everything worked as described. If not or you have any other questions or suggestions, please let me know in the comments. Also, ideas for new projects are always welcome. 🙂


P.S. Many of these projects - especially the hardware projects - cost a lot of time and money. Of course I do this because I enjoy it, but if you appreciate it that I share these information with you, I would be happy about a small donation to the coffee box. 🙂

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