Modbus trouble with Docker

[Josov]

I have trouble to get Modbus working inside a Docker container.
I am using RPI OS 64-bit latest version. Image nodered/node-red:latest
Node.js v16.16.0
Linux 5.15.76-v8+ arm64 LE

Here is how I start the container:

docker run -it -p 1880:1880 -v /home/pi/docker/nodered/node_red_data:/data -v /dev:/dev --group-add dialout --name nodered --device=/dev/ttyACM0 nodered/node-red

The serial Modbus device is:

No flows
No extra nodes installed, just a clean system

I install node-red-contrib-modbus and configure a modbus configuration node, deploy and the result is exit Node-RED with this error:

I tried using serialport@0.15.0, no results

Any ideas welcome!

[Mikka20]

Hi Josov,

I have the same problem.
With the command
"docker run -it -p 1880:1880 -v node_red_data:/data --name node-red --device=/dev/ttyUSB1 nodered/node-red"
docker starts.

With the command
"docker run -it -p 1880:1880 -v node_red_data:/data --name node-red --group-add dialout --device=/dev/ttyUSB1 nodered/node-red" or "docker run -it -u node-red:dialout -p 1880:1880 -v node_red_data:/data --name node-red --device=/dev/ttyUSB1 nodered/node-red"
i get a segfault:
30 Jan 09:51:59 - [info] Started flows
./entrypoint.sh: line 14: 7 Segmentation fault (core dumped) /usr/local/bin/node $NODEOPTIONS node_modules/node-red/red.js --userDir /data $FLOWS

I have installed debian + node-red on the same docker host. in this constellation everything works.

Did you get any further with this problem?

Thx,
Mikka

[Josov]

Hi Mikka,

Nice to hear from you. In the mean time I solved the problem. However I am using docker-compose to install node-red but this is not essential.

Maybe start as follows:
$ docker exec -it node-red bash

Check your ports using:
# ls -l /dev/serial/by-id

Is your port there?
If yes, continue with:
# whoami

If your port is not there: it worked out well using ‘root’ as node-red user. The --group-add dialout did not make the difference. An other thing I had to do to make it work is the following. From the palette I installed node-red-node-serialport (although I did not need it), then go back in the docker container with:

$ docker exec -it node-red bash

And, as your data directory is /data do as follows at the bash prompt:

# cd /data/node_modules/node-red-node-serialport
# npm rebuild --build-from-source
# cd ../serialport
# npm rebuild --build-from-source
# cd ../node-red-contrib-modbus
# npm rebuild --build-from-source

This with user=root did the job.

I am using docker-compose to install node-red and I set the user to root. I am passing the parameters I need in node-red through environment variables, all collected in one file. Here you find a few of them under environment.

node-red:
container_name: nodered
image: nodered/node-red:latest
restart: unless-stopped
user: root
environment:
- MODBUSPORT=$MODBUS_SERIAL_PORT
- P1SERIALPORT=$P1_SERIAL_PORT
network_mode: host
expose:
- "80"
privileged: true
depends_on:
- "mariadb"
- "mqtt"
- "zigbee2mqtt"
volumes:
- /home/pi/docker/nodered/node_red_data:/data
- /home/pi/docker/backup:/backup
- /home/pi/docker/zigbee2mqtt/data:/z2mdata
- /dev:/dev
- /home/pi/.acme.sh/$MYDOMAIN:/certs

Success!

Jos

[dceejay]

Nice - thanks for that.

[Mikka20]

Hi Jos,

thanks for your quick reply.
I will try the days and hopefully report with success.
In the meantime i have created a Bug report. Let's see if one of the developers can help.

Greetings
Mikka