jairov4 / firevm

Get functional and slim VM images from docker containers

FireVM

Utility to create slim VM images from docker container images. The idea behind this is you can leverage the existing great tooling for docker images and get an incredible easy workflow to compose your VM images too.

Example:

# We create our new VM definition via regular container tooling 
docker build -t my-vm-template:latest .
# We create our 200MB QCOW2 VM image from container image
firevm my-vm-template:latest -s 200 -f qcow2 -o my-vm-template.qcow2
# Launch our new VM
sudo virt-install --name my-vm --ram 1024 --disk /my-vm-template.qcow2,bus=virtio \
    --boot hd --network user,model=virtio --nographics --os-type linux --import

Requisites

• Docker CE installed
• QEMU utilities installed
• Python 3.6+

How works?

FireVM tool is inspired in Firecraker's Ignite project which provided a similar idea focused on VMs targeted to run in Firecracker only. Our goal in firevm is to ignite slim and generic cloud VM images suitable for a wider range of hypervisors like KVM and Hyper-V.

The PoC was tested on CentOS 8.

Filesystem interface

Docker images can include the Linux kernel and optionally a linux kernel can be injected by using the --kernel option and specifying a separated docker image for it. Any case, FireVM expects by default the following files:

• Kernel image: /boot/vmlinuz
• initramfs image (optional): /boot/initramfs

Available Kernel Images

They are Docker images holding kernel compiled and ready to use

• jairov4/firevm-kernel:5.10.25-amd64
• jairov4/firevm-kernel:5.4.108-amd64
• jairov4/firevm-kernel:4.19.183-amd64
• jairov4/firevm-kernel:4.14.227-amd64

Compiling own kernel image

cd kernel
make

Troubleshooting

Remember setup your file ACL in home directory for KVM usage to allow qemu user walk in.

sudo setfacl -m u:qemu:rx /home/$USER/