create-vm

#!/bin/bash
# SPDX-FileCopyrightText: The vmnet-broker authors
# SPDX-License-Identifier: Apache-2.0

set -e

CACHE_DIR=".cache"
VMS_DIR=".vms"

ARCH=$(uname -m | sed s/x86_64/amd64/)

IMAGE_URL="https://cloud-images.ubuntu.com/plucky/current/plucky-server-cloudimg-${ARCH}.img"
KERNEL_URL="https://cloud-images.ubuntu.com/plucky/current/unpacked/plucky-server-cloudimg-${ARCH}-vmlinuz-generic"
INITRD_URL="https://cloud-images.ubuntu.com/plucky/current/unpacked/plucky-server-cloudimg-${ARCH}-initrd-generic"

# Generate Random Unicast Locally Administered MAC
generate_mac_address() {
    # -tu1: Type unsigned decimal, 1-byte units
    local bytes=($(od -An -N6 -tu1 /dev/urandom))

    # Make it Unicast Locally Administered
    # (Value AND 254) clears bit 0 (Unicast)
    # (Value OR 2) sets bit 1 (Locally Administered)
    bytes[0]=$(( (bytes[0] & 254) | 2 ))

    printf "%02x:%02x:%02x:%02x:%02x:%02x" "${bytes[@]}"
}

download_image() {
    local url="$1"
    local filename="$2"
    if [ ! -f "$CACHE_DIR/$filename" ]; then
        echo "Downloading $url"
        curl --fail --show-error --location "$url" -o "$CACHE_DIR/$filename.qcow2"
        echo "Converting image to raw format"
        qemu-img convert -f qcow2 -O raw "$CACHE_DIR/$filename.qcow2" "$CACHE_DIR/$filename.tmp"
        rm "$CACHE_DIR/$filename.qcow2"
        echo "Resize image to 20g"
        qemu-img resize "$CACHE_DIR/$filename.tmp" 20g
        mv "$CACHE_DIR/$filename.tmp" "$CACHE_DIR/$filename"
    fi
}

download_kernel() {
    local url="$1"
    local filename="$2"
    if [ ! -f "$CACHE_DIR/kernel" ]; then
        echo "Downloading $url"
        curl --fail --show-error --location "$url" -o "$CACHE_DIR/$filename.tmp.gz"
        echo "Decompressing kernel"
        gzip -d "$CACHE_DIR/$filename.tmp.gz"
        mv "$CACHE_DIR/$filename.tmp" "$CACHE_DIR/$filename"
    fi
}

download_initrd() {
    local url="$1"
    local filename="$2"
    if [ ! -f "$CACHE_DIR/$filename" ]; then
        echo "Downloading $url"
        curl --fail --show-error --location "$url" -o "$CACHE_DIR/$filename.tmp"
        mv "$CACHE_DIR/$filename.tmp" "$CACHE_DIR/$filename"
    fi
}

create_cloud_init_iso() {
    cidata_dir="$VM_DIR/cidata"
    mkdir "$cidata_dir"

    cat <<EOF > "$cidata_dir/user-data"
#cloud-config
password: pass
chpasswd:
  expire: false
EOF

    cat <<EOF > "$cidata_dir/network-config"
version: 2
ethernets:
  eth0:
    match:
      macaddress: ${MAC_ADDRESS}
    set-name: eth0
    dhcp4: true
    dhcp-identifier: mac
EOF

    cat <<EOF > "$cidata_dir/meta-data"
instance-id: ${VM_UUID}
local-hostname: ${VM_NAME}
EOF

    echo "Generating cloud-init ISO..."
    hdiutil makehybrid \
        -o "$VM_DIR/cidata.iso" \
        -joliet \
        -iso \
        -joliet-volume-name cidata \
        -quiet \
        "$cidata_dir/"
}

create_config_json() {
    cat <<EOF > "${VM_DIR}/config.json"
{
  "cpus": 2,
  "memory": 1024,
  "mac": "${MAC_ADDRESS}",
  "bootloader": {
EOF
    if [ "$BOOTLOADER" = "linux" ]; then
        cat <<EOF >> "${VM_DIR}/config.json"
    "type": "linux",
    "kernel": "${VM_DIR}/kernel",
    "initrd": "${VM_DIR}/initrd"
EOF
    elif [ "$BOOTLOADER" = "efi" ]; then
        cat <<EOF >> "${VM_DIR}/config.json"
    "type": "efi",
    "variable-store": "${VM_DIR}/efi_vars.fd"
EOF
    fi
    cat <<EOF >> "${VM_DIR}/config.json"
  },
  "disks": [
    {
      "path": "${VM_DIR}/disk.img",
      "readonly": false
    },
    {
      "path": "${VM_DIR}/cidata.iso",
      "readonly": true
    }
  ]
}
EOF
}

usage() {
  echo "Usage: create-vm [--bootloader=linux|efi] vm-name"
  exit 1
}

BOOTLOADER="linux"
VM_NAME=""

while [[ $# -gt 0 ]]; do
    case $1 in
        --bootloader)
            BOOTLOADER="$2"
            shift 2
            ;;
        --bootloader=*)
            BOOTLOADER="${1#*=}"
            shift
            ;;
        -*)
            echo "Unknown option: $1"
            usage
            ;;
        *)
            if [ -z "$VM_NAME" ]; then
                VM_NAME="$1"
            else
                echo "Error: Multiple VM names specified"
                usage
            fi
            shift
            ;;
    esac
done

if [ "$BOOTLOADER" != "efi" ] && [ "$BOOTLOADER" != "linux" ]; then
    usage
fi

if [ -z "$VM_NAME" ]; then
    usage
fi

VM_DIR="$VMS_DIR/${VM_NAME}"

if [ -d "$VM_DIR" ]; then
    echo "Error: VM directory '${VM_DIR}' already exists"
    exit 1
fi

MAC_ADDRESS=$(generate_mac_address)
VM_UUID=$(uuidgen | tr "A-F" "a-f")

mkdir -p "$CACHE_DIR"
mkdir -p "$VM_DIR"

download_image "$IMAGE_URL" disk.img

if [ "$BOOTLOADER" = "linux" ]; then
    download_kernel "$KERNEL_URL" kernel
    download_initrd "$INITRD_URL" initrd
fi

echo "Creating VM directory..."

cp -c "$CACHE_DIR/disk.img" "$VM_DIR/disk.img"
if [ "$BOOTLOADER" = "linux" ]; then
    cp -c "$CACHE_DIR/kernel" "$VM_DIR/kernel"
    cp -c "$CACHE_DIR/initrd" "$VM_DIR/initrd"
fi

create_cloud_init_iso
create_config_json

echo "Created ${VM_DIR}"