Libvirt container

This container runs a libvirtd instance in an openSUSE Tumbleweed environment.

It will autostart virtual machines that are set to autostart inside libvirt. It will also suspend virtual machines still running when the container is stopped and re-activate those virtual machines again when the container is started again.

It is intended to be run with host networking and has an SSH daemon active to remotely connect for example virt-manager to it. For a correct functioning of the virtualization, this container needs to be run in privileged mode

It will retain virtual machines and VM configuration files using a seperate volume for /var/lib/libvirt and /etc/libvirt/qemu.

Starting container

Start the container as follows:

podman run --privileged --net=host -v /sys/fs/cgroup:/sys/fs/cgroup:rw \
-v /var/lib/libvirt/:/var/lib/libvirt/ -v libvirtd_vm_configs:/etc/libvirt/qemu \
-e ROOT_PASSWORD="some-password" -e SSHD_PORT="some-port" --name some-libvirtd sicho/libvirtd

Where some-libvirtd is the name you want to assign to your container. some-password is the password to set for the root-user, and some-port is the port the SSH daemon will listen on. The SSH port will default to 22 but will then probably fail to start if the host system already has SSH running on port 22. Tip: add -v /root/.ssh:/root/.ssh to share the root SSH keys from the host system with this system.

Auto starting container

Using podman, you can generate a systemd service-file to autostart the container on boot:

podman generate systemd -t 300 --name some-libvirtd > /etc/systemd/system/container-some-libvirtd.service
systemctl daemon-reload
systemctl enable container-some-libvirtd.service

To allow the running virtual machines to suspend correctly when stopping the container, we need to set the podman stop timeout to 5min using the -t 300 option but as systemd itself also has a default timeout of 1m30s we have to override this manually:

systemctl edit container-some-libvirtd

[Service]
TimeoutStopSec=360

Container shell access

Since the container is running an SSH Daemon you can connect to it using SSH to the SSHD_PORT on the host system. Otherwise you can also gain shell access using:

docker exec -ti some-libvirtd /bin/bash

Environment variables

When you start the libvirtd image, you can adjust the configuration of the container by passing one or more environment variables on the podman run command line.

ROOT_PASSWORD

This variable sets the password for the root user inside the container. This password is required to SSH into the host when not using an authorized ssh key.

SSHD_PORT

This variable sets the port the SSH daemon needs to listen on. This defaults to port 22 but will then probably conflict with an SSH daemon already running on the host system as this container is intended to run with host network.

Volumes

/var/lib/libvirt

The volume is used to store the images of the virtual machines

/etc/libvirt/qemu

The volume is used to store the virtual machine configuration files

/sys/fs/cgroup

As this container is running systemd, it requires rw access to the host systems /sys/fs/cgroup. So make sure to mount this volume using -v /sys/fs/cgroup:/sys/fs/cgroup:rw