On internet I found this: RancherVM Images.I have created the qcow2 image containing my edited Linux VM how to add to docker and see it from RancherVM web menu?
Rancher: how to add a qcow2 image?
docker
I understand how to do.First create or convert a qcow2 compressed image(is the qemu format)Then create a dockerfile like this and rename it  Dockerfile FROM rancher/vm-base:0.0.1COPY centos.img  /base_image/centos7.imgCMD [-m 2002m]then import in docker,of course do this where you copied the image(in my case is /root/centos.img and pwd is root)docker build -t centos7:kvmThen open ranchervm webgui,do create instance andput centos7:kvm in image,setup other things how you likeit and click okYou can run the docker image created via kvm via vnc on browser.