Add node-snap7 to the default Docker installation

[mauroalexandre]

I cannot provide the number of users utilizing Siemens PLCs via S7, but I would like to propose that the installation of node-snap7 be included in the Dockerfile by default.

[unocelli]

I propose to create a docker version (tagged s7) with node-snap7

[mauroalexandre]

Also, I believe it to be a good option.

Another option is to create an ARG in the Dockerfile like this:

ARG NODE_SNAP=false

RUN if [ "$NODE_SNAP" = "true" ]; then \
    npm install node-snap7; \
    fi

And build the Docker image with the input argument NODE_SNAP like this:

docker build --build-arg NODE_SNAP=true ...

[unocelli]

Thanks @mauroalexandre
I created the docker version with installed node-snap7 library in frangoteam/fuxa:snap7