Docker Samples

Running BACnet applications in docker is a challenge because the environment that is normally presented to applications is not the one that the host has because the intent is to protect containers (running images) from interfering with or being interfered with by other devices than the host.

Docker has a --network host option so the container does not get its own IP address allocated, which is helpful, but only for unicast traffic. Attempts to “bind” to broadcast addresses of the host fail.

The solution is to have BACpypes3 applications be configured as a foreign device and register with a BBMD on the network. To allow more than one application running on the same host, the application uses an ephemeral port and the operating system will proved provide an unused socket.

A side effect is that subsequent runs of the same image will present most likely not have the same port number, so they will have different BACnet/IPv4 addresses each time they are run. During debugging it might be beneficial to assign a fixed socket number.

This also means that the container can register as a foreign device with some BBMD in the BACnet intranet.

Setting Up

The docker samples are often used with unpublished versions of BACpypes3, so the build scripts include a local build of the package as a wheel.

The root folder of the BACpypes3 project has a bdist.sh script which builds Python eggs and a wheel.