pve-scripts/create_k3s_ready_lxc.sh

#!/usr/bin/env bash
set -euo pipefail

### ---------- helpers ----------
die() { echo "❌ $*" >&2; exit 1; }
info() { echo "▶ $*"; }
ok() { echo "✅ $*"; }

choose_from_list() {
  local prompt="$1"
  shift
  local items=("$@")

  echo
  echo "$prompt"
  echo

  local i=1
  for item in "${items[@]}"; do
    printf "  %2d) %s\n" "$i" "$item"
    ((i++))
  done

  while true; do
    echo
    read -rp "Enter number or exact value: " choice

    # numeric
    if [[ "$choice" =~ ^[0-9]+$ ]] && (( choice >= 1 && choice <= ${#items[@]} )); then
      echo "${items[choice-1]}"
      return
    fi

    # exact match
    for item in "${items[@]}"; do
      if [[ "$choice" == "$item" ]]; then
        echo "$item"
        return
      fi
    done

    echo "❌ Invalid selection. Try again."
  done
}

### ---------- banner ----------
cat <<EOF
=================================================
   Proxmox LXC Creator — K3s READY (No K3s)
=================================================
EOF

### ---------- basic input ----------
read -rp "Container ID: " CT_ID
[[ "$CT_ID" =~ ^[0-9]+$ ]] || die "Container ID must be numeric"

pct status "$CT_ID" &>/dev/null && die "Container ID $CT_ID already exists"

read -rp "Hostname: " HOSTNAME
read -rp "Rootfs size (GB) [16]: " ROOTFS_SIZE
read -rp "Memory (MB) [4096]: " MEMORY
read -rp "CPU cores [2]: " CORES
read -rsp "Root password: " PASSWORD
echo

ROOTFS_SIZE=${ROOTFS_SIZE:-16}
MEMORY=${MEMORY:-4096}
CORES=${CORES:-2}

### ---------- templates ----------
info "Detecting LXC templates..."
mapfile -t TEMPLATES < <(pveam list local | awk '/vztmpl/ {print $1}')
[[ ${#TEMPLATES[@]} -gt 0 ]] || die "No templates found in local storage"

# Prefer Ubuntu if present
DEFAULT_TEMPLATE=""
for t in "${TEMPLATES[@]}"; do
  [[ "$t" =~ ubuntu ]] && DEFAULT_TEMPLATE="$t" && break
done

if [[ -n "$DEFAULT_TEMPLATE" ]]; then
  echo
  read -rp "Ubuntu template found. Use it? [Y/n]: " yn
  if [[ ! "$yn" =~ ^[Nn]$ ]]; then
    TEMPLATE="$DEFAULT_TEMPLATE"
  fi
fi

[[ -z "${TEMPLATE:-}" ]] && TEMPLATE=$(choose_from_list "Select LXC template:" "${TEMPLATES[@]}")

### ---------- bridges ----------
info "Detecting network bridges..."
mapfile -t BRIDGES < <(awk '/iface vmbr/ {print $2}' /etc/network/interfaces)
[[ ${#BRIDGES[@]} -gt 0 ]] || die "No vmbr bridges found"

DEFAULT_BRIDGE="${BRIDGES[0]}"
read -rp "Use default bridge (${DEFAULT_BRIDGE})? [Y/n]: " yn
if [[ "$yn" =~ ^[Nn]$ ]]; then
  BRIDGE=$(choose_from_list "Select network bridge:" "${BRIDGES[@]}")
else
  BRIDGE="$DEFAULT_BRIDGE"
fi

### ---------- summary ----------
cat <<EOF

================== SUMMARY ==================
Container ID : $CT_ID
Hostname     : $HOSTNAME
Template     : $TEMPLATE
Bridge       : $BRIDGE (DHCP)
Disk         : ${ROOTFS_SIZE}G
Memory       : ${MEMORY} MB
Cores        : ${CORES}
============================================

EOF

read -rp "Proceed? [y/N]: " confirm
[[ "$confirm" =~ ^[Yy]$ ]] || die "Aborted by user"

### ---------- create ----------
info "Creating container..."
pct create "$CT_ID" "$TEMPLATE" \
  --hostname "$HOSTNAME" \
  --net0 "name=eth0,bridge=$BRIDGE,ip=dhcp" \
  --memory "$MEMORY" \
  --cores "$CORES" \
  --rootfs "local-lvm:${ROOTFS_SIZE}" \
  --swap 0 \
  --unprivileged 0 \
  --features nesting=1

pct stop "$CT_ID"

info "Applying K3s-compatible LXC configuration..."
cat <<EOF >> /etc/pve/lxc/${CT_ID}.conf
lxc.apparmor.profile: unconfined
lxc.cgroup.devices.allow: a
lxc.cap.drop:
lxc.mount.auto: "proc:rw sys:rw"
EOF

pct start "$CT_ID"
sleep 5

info "Configuring container..."
pct exec "$CT_ID" -- bash -c "echo 'root:$PASSWORD' | chpasswd"

pct exec "$CT_ID" -- bash -c "
apt update &&
apt install -y curl ca-certificates
"

pct exec "$CT_ID" -- bash -c "
cat <<'EOF' > /etc/rc.local
#!/bin/sh -e
if [ ! -e /dev/kmsg ]; then
    ln -s /dev/console /dev/kmsg
fi
mount --make-rshared /
EOF
chmod +x /etc/rc.local
/etc/rc.local
"

ok "Container $CT_ID is ready for K3s installation."
echo "Next step inside container:"
echo "  curl -sfL https://get.k3s.io | sh"