The MAC address spoofing setting is because the container is. Below is the Ubuntu docker config file (located at /etc/default/docker) content.
10 Examples of how to get Docker Container IP Address One thing that is so much fun about the need virtualization paradigm we are heading towards is that in the age of “software defined”, the flexibility of how to do things with infra are much more like programming then working with highly opinionated traditional infrastructure. Along that thread, here are 10 different ways to get a container or docker-machine address using the Docker/Docker-Machine CLI. This doesn’t even go into the remote http API which is slick because the client commands below are actually making calls to the verioned API described.
Much of the motivation to show so many different ways is to help folks see the flexibility that I still run into nearly daily which is hard not to excite a hacker. They can also be viewed in this.