d2vm (Docker to Virtual Machine)

Build virtual machine image from Docker images

The project is heavily inspired by the article and the work done by iximiuz on docker-to-linux.

Many thanks to him.

Status: alpha

Supported Environments:

Only building Linux Virtual Machine images is supported.

Starting from v0.1.0, d2vm automatically run build and convert commands inside Docker when not running on linux or when running without root privileges.

Note: windows should be working, but is totally untested.

Supported VM Linux distributions:

Working and tested:

• Ubuntu (18.04+) Luks support is available only on Ubuntu 20.04+
• Debian (stretch+) Luks support is available only on Debian buster+
• Alpine
• CentOS (8+)

Unsupported:

• RHEL

The program uses the /etc/os-release file to discover the Linux distribution and install the Kernel, if the file is missing, the build cannot succeed.

Obviously, Distroless images are not supported.

Prerequisites

osx

• Docker
• QEMU (optional)
• VirtualBox (optional)

Linux

• Docker
• util-linux
• udev
• parted
• e2fsprogs
• mount
• tar
• extlinux
• qemu-utils
• cryptsetup (when using LUKS)
• QEMU (optional)
• VirtualBox (optional)

Getting started

Install

With Docker

Note: this will only work if both the source context (and Dockerfile) and the output directory are somewhere inside the directory where you run the command.

docker pull linkacloud/d2vm:latest
alias d2vm="docker run --rm -it -v /var/run/docker.sock:/var/run/docker.sock --privileged -v \$PWD:/d2vm -w /d2vm linkacloud/d2vm:latest"

wich d2vm

d2vm: aliased to docker run --rm -it -v /var/run/docker.sock:/var/run/docker.sock --privileged -v $PWD:/d2vm -w /d2vm linkacloud/d2vm:latest

With Homebrew

brew install linka-cloud/tap/d2vm

From release

Download the latest release for your platform from the release page.

Extract the tarball, then move the extracted d2vm binary to somewhere in your $PATH (/usr/local/bin for most users).

VERSION=$(git ls-remote --tags https://github.com/linka-cloud/d2vm |cut -d'/' -f 3|tail -n 1)
OS=$(uname -s | tr '[:upper:]' '[:lower:]')
ARCH=$([ "$(uname -m)" = "x86_64" ] && echo "amd64" || echo "arm64")
curl -sL "https://github.com/linka-cloud/d2vm/releases/download/${VERSION}/d2vm_${VERSION}_${OS}_${ARCH}.tar.gz" | tar -xvz d2vm
sudo mv d2vm /usr/local/bin/

From source

Clone the git repository:

git clone https://github.com/linka-cloud/d2vm && cd d2vm

Install using the make, docker and the Go tool chain:

make install

The d2vm binary is installed in the $GOBIN directory.

which d2vm

/go/bin/d2vm

Generate shell completion

The d2vm program supports shell completion for bash, zsh and fish.

It can be enabled by running the following command:

source <(d2vm completion $(basename $SHELL))

Or you can install the completion file in the shell completion directory by following the instructions:

d2vm completion $(basename $SHELL) --help

Converting an existing Docker Image to VM image:

d2vm convert --help

Convert Docker image to vm image

Usage:
  d2vm convert [docker image] [flags]

Flags:
      --append-to-cmdline string   Extra kernel cmdline arguments to append to the generated one
      --boot-size uint             Size of the boot partition in MB (default 100)
      --force                      Override output qcow2 image
  -h, --help                       help for convert
      --keep-cache                 Keep the images after the build
      --luks-password string       Password to use for the LUKS encrypted root partition. If not set, the root partition will not be encrypted
      --network-manager string     Network manager to use for the image: none, netplan, ifupdown
  -o, --output string              The output image, the extension determine the image format, raw will be used if none. Supported formats: qcow2 qed raw vdi vhd vmdk (default "disk0.qcow2")
  -p, --password string            Optional root user password
      --pull                       Always pull docker image
      --push                       Push the container disk image to the registry
      --raw                        Just convert the container to virtual machine image without installing anything more
  -s, --size string                The output image size (default "10G")
      --split-boot                 Split the boot partition from the root partition
  -t, --tag string                 Container disk Docker image tag

Global Flags:
      --time string   Enable formated timed output, valide formats: 'relative (rel | r)', 'full (f)' (default "none")
  -v, --verbose       Enable Verbose output

Create an image based on the ubuntu official image:

sudo d2vm convert ubuntu -o ubuntu.qcow2 -p MyP4Ssw0rd

Pulling image ubuntu
Inspecting image ubuntu
No network manager specified, using distribution defaults: netplan
Docker image based on Ubuntu 22.04.1 LTS (Jammy Jellyfish)
Building kernel enabled image
Creating vm image
Creating raw image
Mounting raw image
Creating raw image file system
Copying rootfs to raw image
Setting up rootfs
Installing linux kernel
Unmounting raw image
Writing MBR
Converting to qcow2

You can now run your ubuntu image using the created ubuntu.qcow2 image with qemu:

d2vm run qemu ubuntu.qcow2

SeaBIOS (version 1.13.0-1ubuntu1.1)


iPXE (http://ipxe.org) 00:03.0 CA00 PCI2.10 PnP PMM+BFF8C920+BFECC920 CA00



Booting from Hard Disk...

SYSLINUX 6.04 EDD 20191223 Copyright (C) 1994-2015 H. Peter Anvin et al
Now booting the kernel from SYSLINUX...
Loading /boot/vmlinuz... ok
Loading /boot/initrd.img...ok
[    0.000000] Linux version 5.4.0-109-generic (buildd@ubuntu) (gcc version 9)
[    0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz ro root=UUID=b117d206-b8
[    0.000000] KERNEL supported cpus:
[    0.000000]   Intel GenuineIntel
[    0.000000]   AMD AuthenticAMD
[    0.000000]   Hygon HygonGenuine
[    0.000000]   Centaur CentaurHauls
[    0.000000]   zhaoxin   Shanghai

...

Welcome to Ubuntu 20.04.4 LTS!

[    3.610631] systemd[1]: Set hostname to <localhost>.
[    3.838984] systemd[1]: Created slice system-getty.slice.
[  OK  ] Created slice system-getty.slice.
[    3.845038] systemd[1]: Created slice system-modprobe.slice.
[  OK  ] Created slice system-modprobe.slice.
[    3.852054] systemd[1]: Created slice system-serial\x2dgetty.slice.
[  OK  ] Created slice system-serial\x2dgetty.slice.

...

Ubuntu 20.04.4 LTS localhost ttyS0

localhost login: 

Log in using the root user and the password configured at build time.

localhost login: root
Password:


Welcome to Ubuntu 20.04.4 LTS (GNU/Linux 5.4.0-109-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

This system has been minimized by removing packages and content that are
not required on a system that users do not log into.

To restore this content, you can run the 'unminimize' command.

The programs included with the Ubuntu system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by
applicable law.

root@localhost:~#

Type poweroff to shut down the vm.

Building a VM Image from a Dockerfile

The example directory contains very minimalistic examples:

cd examples

ubuntu.Dockerfile :

FROM ubuntu

RUN apt update && apt install -y openssh-server && \
    echo "PermitRootLogin yes" >> /etc/ssh/sshd_config

Build the vm image:

The build command take most of its flags and arguments from the docker build command.

d2vm build --help

Build a vm image from Dockerfile

Usage:
  d2vm build [context directory] [flags]

Flags:
      --append-to-cmdline string   Extra kernel cmdline arguments to append to the generated one
      --boot-size uint             Size of the boot partition in MB (default 100)
      --build-arg stringArray      Set build-time variables
  -f, --file string                Name of the Dockerfile
      --force                      Override output qcow2 image
  -h, --help                       help for build
      --keep-cache                 Keep the images after the build
      --luks-password string       Password to use for the LUKS encrypted root partition. If not set, the root partition will not be encrypted
      --network-manager string     Network manager to use for the image: none, netplan, ifupdown
  -o, --output string              The output image, the extension determine the image format, raw will be used if none. Supported formats: qcow2 qed raw vdi vhd vmdk (default "disk0.qcow2")
  -p, --password string            Optional root user password
      --push                       Push the container disk image to the registry
      --raw                        Just convert the container to virtual machine image without installing anything more
  -s, --size string                The output image size (default "10G")
      --split-boot                 Split the boot partition from the root partition
  -t, --tag string                 Container disk Docker image tag

Global Flags:
      --time string   Enable formated timed output, valide formats: 'relative (rel | r)', 'full (f)' (default "none")
  -v, --verbose       Enable Verbose output

sudo d2vm build -p MyP4Ssw0rd -f ubuntu.Dockerfile -o ubuntu.qcow2 .

Or if you want to create a VirtualBox image:

sudo d2vm build -p MyP4Ssw0rd -f ubuntu.Dockerfile -o ubuntu.vdi .

KubeVirt Container Disk Images

Using the --tag flag with the build and convert commands, you can create a Container Disk Image for KubeVirt.

The --push flag will push the image to the registry.

Complete example

A complete example setting up a ZSH workstation is available in the examples/full directory.

Internal Dockerfile templates

You can find the Dockerfiles used to install the Kernel in the templates directory.

TODO / Questions:

• Create service from ENTRYPOINT CMD WORKDIR and ENV instructions ?
• Inject Image ENV variables into .bashrc or other service environment file ?
• Use image layers to create rootfs instead of container ?

Acknowledgments

The run commands are adapted from linuxkit.