CANopen gateway in Docker

The dockerfile creates a CANopen master with gateway functionality. Using the commands interface one can control a CANopen network. The gateway is exposed at port 6000.

Dependencies

This project is based upon CANopenSocket and CANopenNode.

Building the container image

This project should build with the default Docker build engine, but also buildx is supported for creating cross-platform container images. Considering you're targetting embedded devices I'd guess you're cross building, so let's demonstrate docker buildx here.

1. Make sure that Docker buildx is installed and that the Docker experimental features are enabled in your environment.
2. Either create a new or use a already created buildx engine:

$ docker buildx create --name crossbuilder
$ docker buildx use crossbuilder

3. When building, we also want to push the build output to Docker hub so make sure this is also setup correctly and that're logging in:

$ docker login

4. Now build (and push) the container image:

$ docker buildx build --platform linux/arm,linux/arm64,linux/amd64 -t geoffreyvl/canopensocket . --push

5. On Docker Hub your container image will appear
6. We can now use the container image, for example let's inspect it:

$ docker buildx imagetools inspect geoffreyvl/canopensocket
Name:      docker.io/geoffreyvl/canopensocket:latest
MediaType: application/vnd.docker.distribution.manifest.list.v2+json
Digest:    sha256:bd24fa61e43427f1113027e299b63c455510bb5d0fe9e2600d7db3fdde7ea58a
        
Manifests: 
Name:      docker.io/geoffreyvl/canopensocket:latest@sha256:8d953afb62cd220e44c45abb0247c6ce6726b43bfe2b825475672e14e1996684
MediaType: application/vnd.docker.distribution.manifest.v2+json
Platform:  linux/arm/v7
        
Name:      docker.io/geoffreyvl/canopensocket:latest@sha256:388e652c8e7796f6746fa45afedbb0c1fd8d2ad29d28d4c3c6228084b549b98c
MediaType: application/vnd.docker.distribution.manifest.v2+json
Platform:  linux/arm64
        
Name:      docker.io/geoffreyvl/canopensocket:latest@sha256:6bfeb074195e93e4f4774bc08f9539c6f4f34042e124805485af0930d51e4ceb
MediaType: application/vnd.docker.distribution.manifest.v2+json
Platform:  linux/amd64

Using the container image

Setup CAN

On your native host machine make sure that your CAN interface is up and running. We will use that interface within the Docker container.

$ ip link set can0 type can bitrate 250000
$ ip link set can0 up

If you don't own a can interface can create a virtual can device:

$ sudo modprobe vcan
$ sudo ip link add dev vcan0 type vcan
$ sudo ip link set up vcan0

Verify using ifconfig:

$ ifconfig
vcan0: flags=193<UP,RUNNING,NOARP>  mtu 72
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 1000  (UNSPEC)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Running a container

Either you build your own Docker image using the provided Dockerfile, or you use a 3rd party provided Docker image. Following guidelines assume the latter.

To run the container software you must pass the can interface into the container using the -e CAN=<if> option. To run the process in background/detached mode pass the -d option. Run the container as following:

$ docker run --rm --network host -d -e CAN=can0 "geoffreyvl/canopensocket:latest"

Verify that the container is running:

$ docker container ls

Interact with the CANopen gateway

On your host system make sure to have the canopencomm application. It's part of the CANopenSocket sources, but you need to compile it from source. To send commands through your gateway, use syntax according to the example below:

$ canopencomm -t localhost -p 6000

For more examples visit the CANopenSocket repo.

Monitoring

You can use a second terminal to dump the traffic at your can0 interface:

$ candump can0
...
 can0  701   [1]  7F
 can0  000   [2]  01 01
 can0  181   [2]  00 00
 can0  701   [1]  05