Docker build using a local repo on host?

What I want to to is build a simple me container running centos7 but the VM/container has no internet access so I have a local repo that I can mount on the VM via NFS. Now when I want to do a yum update or yum install in the Dockerfile how do I refer to the VM’s local filesystem? Looking here I’m not sure i can:

Sure I can do it during a docker run but I want to install packages during the build process. I can update the CentOS-Base.repo and copy that to the container but how do I NFS/mount the repo in the container for the building process?

Would love to know if there was a solution found during this, as I’m trying to do the exact same thing… We have a centos host with a local yum repo. I can bind mount it to the docker container no problem and create a repo in the container, but I’d like to be able to install packages from that repository during build, not after the container is already running.