AlpineLinux Firecracker

boot-alpine-in-firecracker.sh

# download
latest=$(basename $(curl -fsSLI -o /dev/null -w  %{url_effective} https://github.com/firecracker-microvm/firecracker/releases/latest))
curl -LOJ https://github.com/firecracker-microvm/firecracker/releases/download/${latest}/firecracker-${latest}-$(uname -m)
mv firecracker-${latest}-$(uname -m) firecracker
chmod +x firecracker

# rootfs
# =========
# qemu-img create -f raw alpine.rootfs.ext4 1G
fallocate -l 1G ubuntu.rootfs.ext4
mkfs.ext4 ./alpine.rootfs.ext4
mkdir /tmp/rootfs
sudo mount alpine.rootfs.ext4 /tmp/rootfs

curl -OJ https://mirrors.aliyun.com/alpine/v3.12/releases/x86_64/alpine-minirootfs-3.12.0-x86_64.tar.gz
sudo tar zxvf alpine-minirootfs-3.12.0-x86_64.tar.gz -C /tmp/rootfs/
# for mirror
sudo cp /etc/apk/repositories /tmp/rootfs/etc/apk/repositories
sudo cp /etc/resolv.conf /tmp/rootfs/etc
sudo chroot /tmp/rootfs/ /bin/sh

apk add alpine-base util-linux linux-virt haveged
rc-update add haveged
echo root:root | chpasswd
for svc in devfs procfs sysfs; do ln -fs /etc/init.d/$svc /etc/runlevels/boot; done
exit

ln -s agetty /etc/init.d/agetty.ttyS0
echo ttyS0 > /etc/securetty
rc-update add agetty.ttyS0 default

# this initramfs contain required ext4 module
sudo cp /tmp/rootfs/boot/initramfs-virt initramfs-virt
sudo cp /tmp/rootfs/boot/vmlinuz-virt vmlinuz-virt

sudo umount /tmp/rootfs

# kernel
# ==========
curl -LOC- https://raw.githubusercontent.com/torvalds/linux/master/scripts/extract-vmlinux
chmod +x extract-vmlinux
./extract-vmlinux $PWD/vmlinuz-virt > vmlinux-virt

# config & start
# ==========
cat <<CONF > alpine.json
{
  "boot-source": {
    "initrd_path": "initramfs-virt",
    "kernel_image_path": "vmlinux-virt",
    "boot_args": "console=ttyS0 reboot=k panic=1 pci=off modules=virtio_mmio,ext4 rootfstype=ext4"
  },
  "drives": [
    {
      "drive_id": "rootfs",
      "path_on_host": "alpine.rootfs.ext4",
      "is_root_device": true,
      "is_read_only": false
    }
  ],
  "machine-config": {
    "vcpu_count": 1,
    "mem_size_mib": 1024,
    "ht_enabled": false
  }
}
CONF

./firecracker --api-sock /tmp/firecracker.socket --config-file alpine.json

# exit
# ==========
# api request
curl --unix-socket /tmp/firecracker.socket -i \
    -X PUT "http://localhost/actions" \
    -H  "accept: application/json" \
    -H  "Content-Type: application/json" \
    -d '{"action_type": "SendCtrlAltDel"}'
# in vm
reboot