docker and nc netcat

[riker65]

Hi
wondering how to invoke the changes using netcat in docker environment?

nc localhost 5051

does not do anything

in base.json

..
  "request": [
	    { "type": "cpu-temp", "processors": 1 },
	   {
      "type": "modbus",
      "io": "config/usb_id.json",
      "devices": {
        "17": 	{
          "type": "rover",
          "server": { "port": 5051 }
..

[retrodaredevil]

When using any piece of software with docker, you have to manually expose the ports you want accessible in your docker compose file with a ports section:

services:
  solarthing:
    # ...
    ports
      - "127.0.0.1:5051:5051"

Notice that I use the 127.0.0.1 to bind only to localhost, so that other devices on your network cannot access it. This is a security feature that is automatically set up for the native install, but requires that manual configuration for the docker install.

Now, once you do that, it's not going to work yet. This is because of that security feature the native install has, that doesn't work well with the docker install and that port mapping.

We need to tell the SolarThing docker container to listen on all interfaces for 5051. Instead of { "port": 5051 }, we need to change it to { "port": 5051, "bind": "0.0.0.0" }.

Once you do that and restart/recreate the container, it should work just like a native install.

[retrodaredevil]

Alternatively, you can ignore everything I said in the last comment and run this whenever you need to access the configuration server:

# Instead of this 
nc localhost 5051
# do this 
docker compose exec solarthing-service-name-here nc localhost 5051

The reason that will work without any of the configuration I mentioned before is that you're running the netcat command inside the container, so no port mapping is needed and you're accessing it through localhost, so the bind address doesn't need to change.

I'm not at my computer now and cannot confirm that the nc command is actually available through the docker compose exec command, but honestly the docker compose exec command is probably the easier way of accessing the configuration server. I'll try to make sure that's possible in a future version of SolarThing.

Thanks for bringing this to my attention. This clearly needs some updated documentation to accommodate docker installs.

[riker65]

Thanks for the fast response
Will check

[riker65]

looks like I need more deails.
unclear for me - docker newbee - which service is running.

sudo docker compose exec solarthing-request nc localhost 5051
 **service "solarthing-request" is not running**

docker ps-all shows:

35f6c7b5e2ef   ghcr.io/wildmountainfarms/solarthing:latest   "java -XX:ErrorFile=…"   27 hours ago   Up 3 minutes             solarthing-main

following the manual, I used the standard compose

services:
  main:
    image: 'ghcr.io/wildmountainfarms/solarthing:latest'
    container_name: solarthing-main
    restart: 'unless-stopped'
    command: run --base config/base.json
    group_add: # this is only necessary if you are using a user other than root
      - dialout
    cap_add:
      - SYS_RAWIO
   devices:
      - '/dev/serial/by-id/usb-1a86_USB2.0-Ser_-if00-port0:/dev/serial/by-id/usb-1a86_USB2.0-Ser_-if00-port0'
    volumes:

      - './main/config:/app/config:ro'
      - './main/logs:/app/logs'
    ports:
      - "127.0.0.1:5051:5051" 

do I need to start solarting-service here?
I thought in base.json

type request
defines the service and rover device

{
  "type": "request",
  "source": "rpi3solar",
  "fragment": 3,
  "unique": 30,
  "analytics_enabled": false,
  "databases": [ 
	"config/mqtt_lh_request.json"
	],
  "request": [
	    { "type": "cpu-temp", "processors": 1 },
	   {
      "type": "modbus",
      "io": "config/usb_id.json",
      "devices": {
        "17": 	{
          "type": "rover",
          "server": { "port": 5051 }
				}
			}
		}
	]
	}

thanks a lot Thomas

[riker65]

using
sudo docker compose exec main nc localhost 5051
error:
OCI runtime exec failed: exec failed: unable to start container process: exec: "nc": executable file not found in $PATH: unknown

[retrodaredevil]

Yeah it looks like the docker compose exec isn't working to run the command nc because that command is not installed inside the container. I will need to update the docker container myself so that nc is supported out of the box.

In the meantime, you can refer to my first comment if you want to be able to access the configuration server for a docker install.

[retrodaredevil]

ffdbfed addresses this. I will release SolarThing v2025.1.1 at some point, and that docker image will allow you to be able to access nc with docker compose exec service-name nc.

For a technical reasons (jitpack is down today), I cannot make a release yet.

[retrodaredevil]

Feel free to try out docker compose exec main nc localhost 5051 with the latest Docker image.

v2025.1.1 fixes this.