✨ feat: Add package docker-to-rootfs (#121)

This package will handle creating the rootfs needed by CrosVM

> More info incoming

packages/docker-to-rootfs/Dockerfile

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+# https://github.com/iximiuz/docker-to-linux/blob/master/Dockerfile
+
+FROM amd64/debian:bullseye
+LABEL com.iximiuz-project="docker-to-linux"
+RUN apt-get -y update
+RUN apt-get -y install extlinux fdisk

packages/docker-to-rootfs/README.md

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+# Docker to RootFS
+
+We are building the rootfs as a docker image, mainly for consistency and ease of use.
+So, to convert the Docker image to a rootfs good enough to run inside CrosVM we use this script
+
+Run it like so:
+```bash
+./make your-docker-image
+```
+
+TODO:
+1. Make sure the docker image name passed in exists
+2. Reduce the dependencies of this script to 1 (If possible)
+3. Extract not only the rootfs, but also kernel and initrd
+4. Add a way to pass in the size of the rootfs the user wants

packages/docker-to-rootfs/create_image.sh

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+#!/bin/bash
+
+set -e
+
+UID_HOST=$1
+GID_HOST=$2
+VM_DISK_SIZE_MB=$3
+
+echo_blue() {
+    local font_blue="\033[94m"
+    local font_bold="\033[1m"
+    local font_end="\033[0m"
+
+    echo -e "\n${font_blue}${font_bold}${1}${font_end}"
+}
+
+echo_blue "[Create disk image]"
+[ -z "${VM_DISK_SIZE_MB}" ] && VM_DISK_SIZE_MB=1024
+VM_DISK_SIZE_SECTOR=$(expr $VM_DISK_SIZE_MB \* 1024 \* 1024 / 512)
+dd if=/dev/zero of=/os/${DISTR}.img bs=${VM_DISK_SIZE_SECTOR} count=512
+
+echo_blue "[Make partition]"
+echo "type=83,bootable" | sfdisk /os/${DISTR}.img
+
+echo_blue "\n[Format partition with ext4]"
+losetup -D
+LOOPDEVICE=$(losetup -f)
+echo -e "\n[Using ${LOOPDEVICE} loop device]"
+losetup -o $(expr 512 \* 2048) ${LOOPDEVICE} /os/${DISTR}.img
+mkfs.ext4 ${LOOPDEVICE}
+
+echo_blue "[Copy ${DISTR} directory structure to partition]"
+mkdir -p /os/mnt
+mount -t auto ${LOOPDEVICE} /os/mnt/
+cp -a /os/${DISTR}.dir/. /os/mnt/
+
+echo_blue "[Setup extlinux]"
+extlinux --install /os/mnt/boot/
+cp /os/syslinux.cfg /os/mnt/boot/syslinux.cfg
+rm /os/mnt/.dockerenv
+
+echo_blue "[Unmount]"
+umount /os/mnt
+losetup -D
+
+echo_blue "[Write syslinux MBR]"
+dd if=/usr/lib/syslinux/mbr/mbr.bin of=/os/${DISTR}.img bs=440 count=1 conv=notrunc
+
+#echo_blue "[Convert to qcow2]"
+#qemu-img convert -c /os/${DISTR}.img -O qcow2 /os/${DISTR}.qcow2
+
+[ "${UID_HOST}" -a "${GID_HOST}" ] && chown ${UID_HOST}:${GID_HOST} /os/${DISTR}.img
+
+rm -r /os/${DISTR}.dir /os/${DISTR}.tar

packages/docker-to-rootfs/make.sh

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+#!/bin/bash
+
+# Define colors
+COL_RED="\033[0;31m"
+COL_GRN="\033[0;32m"
+COL_END="\033[0m"
+
+# Get current user and group IDs
+USER_ID=$(id -u)
+GROUP_ID=$(id -g)
+
+# Set default disk size
+VM_DISK_SIZE_MB=${VM_DISK_SIZE_MB:-4096}
+
+# Set repository name
+REPO="nestri"
+
+# Function to create a tar archive from a Docker image
+create_tar() {
+  local name=$1
+  echo -e "\n${COL_GRN}[Dump $name directory structure to tar archive]${COL_END}"
+  docker export -o $name.tar $(docker run -d $name /bin/true)
+}
+
+# Function to extract a tar archive
+extract_tar() {
+  local name=$1
+  echo -e "\n${COL_GRN}[Extract $name tar archive]${COL_END}"
+  docker run -it \
+    -v $(pwd):/os:rw \
+    $REPO/builder bash -c "mkdir -p /os/$name.dir && tar -C /os/$name.dir --numeric-owner -xf /os/$name.tar"
+}
+
+# Function to create a disk image
+create_image() {
+  local name=$1
+  echo -e "\n${COL_GRN}[Create $name disk image]${COL_END}"
+  docker run -it \
+    -v $(pwd):/os:rw \
+    -e DISTR=$name \
+    --privileged \
+    --cap-add SYS_ADMIN \
+    $REPO/builder bash /os/create_image.sh $USER_ID $GROUP_ID $VM_DISK_SIZE_MB
+}
+
+# Function to ensure builder is ready
+ensure_builder() {
+  echo -e "\n${COL_GRN}[Ensure builder is ready]${COL_END}"
+  if [ "$(docker images -q $REPO/builder)" = '' ]; then
+    docker build -f Dockerfile -t $REPO/builder .
+  fi
+}
+
+# Function to run builder interactively
+run_builder_interactive() {
+  docker run -it \
+    -v $(pwd):/os:rw \
+    --cap-add SYS_ADMIN \
+    $REPO/builder bash
+}
+
+# Function to clean up
+clean_up() {
+  echo -e "\n${COL_GRN}[Remove leftovers]${COL_END}"
+  rm -rf mnt debian.* alpine.* ubuntu.*
+  clean_docker_procs
+  clean_docker_images
+}
+
+# Function to clean Docker processes
+clean_docker_procs() {
+  echo -e "\n${COL_GRN}[Remove Docker Processes]${COL_END}"
+  if [ "$(docker ps -qa -f=label=com.iximiuz-project=$REPO)" != '' ]; then
+    docker rm $(docker ps -qa -f=label=com.iximiuz-project=$REPO)
+  else
+    echo "<noop>"
+  fi
+}
+
+# Function to clean Docker images
+clean_docker_images() {
+  echo -e "\n${COL_GRN}[Remove Docker Images]${COL_END}"
+  if [ "$(docker images -q $REPO/*)" != '' ]; then
+    docker rmi $(docker images -q $REPO/*)
+  else
+    echo "<noop>"
+  fi
+}
+
+# Main script
+if [ $# -lt 1 ]; then
+  echo "Usage: $0 <image_name> [clean|builder-interactive]"
+  exit 1
+fi
+
+IMAGE_NAME=$1
+
+case $2 in
+  builder-interactive)
+    run_builder_interactive
+    ;;
+  clean)
+    clean_up
+    ;;
+esac
+
+ensure_builder
+create_tar $IMAGE_NAME
+extract_tar $IMAGE_NAME
+create_image $IMAGE_NAME
+
+# Extract kernel `` virt-builder --get-kernel "${IMAGE_NAME}.img" -o . ``

packages/docker-to-rootfs/syslinux.cfg

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+DEFAULT linux
+  SAY Now booting the kernel from SYSLINUX...
+ LABEL linux
+  KERNEL /vmlinuz
+  APPEND rw root=/dev/sda1 initrd=/initrd.img