Quickly create a temporary LXC Debian VM for small experiments

create-test-vm.sh

#!/bin/bash
set -euo pipefail

NAME="${1:-test-vm}"
PASSWORD="${2:-password}"
export LXD_DIR="${LXD_DIR:-/var/lib/lxd}"

command -v lxc >/dev/null || { echo "Missing command: lxc" >&2; exit 1; }
[ -S "$LXD_DIR/unix.socket" ] || { echo "Missing LXD socket: $LXD_DIR/unix.socket" >&2; exit 1; }

USER_DATA=$(cat <<EOF
#cloud-config
hostname: $NAME
create_hostname_file: true
packages:
  - openssh-server
chpasswd:
  list: |
    root:$PASSWORD
    user:$PASSWORD
  expire: false
ssh_pwauth: true
users:
  - default
  - name: user
    groups: sudo
    shell: /bin/bash
    sudo: ALL=(ALL) NOPASSWD:ALL
    lock_passwd: false
runcmd:
  - systemctl enable ssh || true
  - systemctl restart ssh || true
EOF
)

echo "Creating $NAME"
sudo lxc info "$NAME" >/dev/null 2>&1 && sudo lxc delete -f "$NAME" || true
sudo lxc launch images:debian/13/cloud "$NAME" --ephemeral --config=user.user-data="$USER_DATA" >/dev/null
for _ in $(seq 1 60); do
  STATUS="$(sudo lxc exec "$NAME" -- cloud-init status 2>/dev/null || true)"
  [ "$STATUS" = "status: done" ] && break
  sleep 2
done
IP="$(sudo lxc list "$NAME" -c 4 --format csv | head -n1)"

echo "Status: ${STATUS:-unknown}"
echo "Instance: $NAME"
echo "IP: ${IP:-not available}"
echo "Login: user/$PASSWORD"
echo "Shell: sudo lxc exec $NAME -- bash"
echo "SSH: ssh user@${IP:-<ip>}"
echo "Remove: instance is ephemeral and will be deleted when stopped; force remove: sudo lxc delete -f $NAME"