labstrap

Bootstrap VM images for Vlab

Pre-built images

The Auto builds release holds VM images built on GitHub Actions.

Building the image locally

Build Docker image:

docker build -t labstrap .

Grab a base image from http://download.proxmox.com/images/system/ or a mirror site at your option.

Run the build script in Docker, supplying the image and a rootfs directory:

docker run --rm -it --name=labstrap --privileged \
  -v "$PWD":/srv:ro \
  -v /path/to/rootfs:/target \
  -v /path/to/image.tar.zst:/input.tar.zst:ro \
  labstrap

Pack the generated image:

sudo tar cf output.tar.zst --zstd -C /path/to/rootfs .

Debugging locally

Systemd-nspawn

Notes:

• It's recommended to test container image in a VM, as the configuration of systemd-nspawn may need to change system network configuration.
• Host and guest both need systemd-network to manage their network.
• You MUST NOT use "host networking", otherwise bind() to /tmp/.X11-unix/X0 will throw an error (if you are using X in host).

Following insts are tested in Debian 11.

1. Set iptables to legacy

   Systemd-nspawn in Debian 11 still requires iptables-legacy.

   # update-alternatives --set iptables /usr/sbin/iptables-legacy

2. Set NAT with iptables. Assuming that your network interface is ens33.

   # iptables -t nat -A POSTROUTING -o ens33 -j MASQUERADE
   # iptables -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
   # iptables -A FORWARD -i ve-+ -o ens33 -j ACCEPT

3. Prepare Vlab software

   At least the following files and folders should be copied to local:

   /opt/vlab/applications/
   /opt/vlab/bin/
   /opt/vlab/path.sh
   /opt/vlab/share/
   

   scp does not perserve POSIX attrs by default, so rsync is more recommended:

   $ rsync -avH vlab-container:/opt/vlab/applications .
   $ rsync -avH vlab-container:/opt/vlab/bin .
   $ rsync -avH vlab-container:/opt/vlab/path.sh .
   $ rsync -avH vlab-container:/opt/vlab/share .
   

4. Boot container

   # systemd-nspawn -D /path/to/rootfs -M ubuntu -n --boot --resolv-conf=copy-host -p 5900:5900 --bind=/path/to/opt/vlab:/opt/vlab

Configuring container network without systemd-networkd on host

(If you just wanna run labstrap on your Linux host without a VM)

Following insts are tested in Arch Linux (2022/07).

1. Start container with systemd-nspawn -D /path/to/rootfs -M vlab-ubuntu -n -U --boot --bind=/path/to/opt/vlab:/opt/vlab

2. Set a static IP for ve-vlab-ubuntu in host: ip address add 192.168.233.1/24 dev ve-vlab-ubuntu

3. Activate ve-vlab-ubuntu in host: ip link set ve-vlab-ubuntu up

4. Configure network in container. Add file /etc/systemd/network/20-wired.network with:

   [Match]
   Name=host0
   
   [Network]
   Address=192.168.233.2/24
   Gateway=192.168.233.1
   DNS=8.8.8.8
   

   And restart systemd-networkd.service.

5. Configure NAT in host.

   iptables -t nat -A POSTROUTING -s 192.168.233.0/24 -j MASQUERADE
   iptables -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
   iptables -A FORWARD -i ve-vlab-ubuntu -j ACCEPT
   

6. Connect to container with VNC: vncviewer 192.168.233.2