Documentation: detail docker-in-docker requirements

[alexmaras]

I'd recommend documenting the requirements for running this wrapper if you're already running meltano in docker. This is possible, but requires the /tmp directory to be mounted from the host to the meltano container.

This ensures that /tmp/config.json can be accessed, as the python script uses mktemp to create a directory in /tmp such as /tmp/tmp.BNlf296WXX, which can then be mapped down to the airbyte container. Due to the way docker-in-docker works, the volume mounts are mounts that exist on the host, not the meltano container, so it needs to be bind-mounted for it to show up in the airbyte image.