d2vm

README

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.

Supported VM Linux distributions:

Working and tested:

• Ubuntu (18.04+)
• Debian (stretch+)
• 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.

Getting started

Install from release

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

Extract the tarball:

tar -xvzf <RELEASE-TARBALL-NAME>.tar.gz

Move the extracted d2vm binary to somewhere in your $PATH (/usr/local/bin for most users).

Install 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
  -f, --force                      Override output qcow2 image
  -h, --help                       help for convert
      --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            The Root user password (default "root")
      --pull                       Always pull docker image
      --raw                        Just convert the container to virtual machine image without installing anything more
  -s, --size string                The output image size (default "10G")

Global Flags:
  -t, --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
      --build-arg stringArray      Set build-time variables
  -f, --file string                Name of the Dockerfile
      --force                      Override output image
  -h, --help                       help for build
      --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            Root user password (default "root")
      --raw                        Just convert the container to virtual machine image without installing anything more
  -s, --size string                The output image size (default "10G")

Global Flags:
  -t, --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 .

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.

Documentation

Index

• Variables
• func Convert(ctx context.Context, img string, opts ...ConvertOption) error
• func MoveFile(sourcePath, destPath string) error
• func NewImage(ctx context.Context, tag string, imageTmpPath string) (*image, error)
• func OutputFormats() []string
• type Builder
  • func NewBuilder(ctx context.Context, workdir, imgTag, disk string, size int64, ...) (Builder, error)
• type ConvertOption
  • func WithCmdLineExtra(cmdLineExtra string) ConvertOption
  • func WithNetworkManager(networkManager NetworkManager) ConvertOption
  • func WithOutput(output string) ConvertOption
  • func WithPassword(password string) ConvertOption
  • func WithRaw(raw bool) ConvertOption
  • func WithSize(size int64) ConvertOption
• type DockerImage
  • func (i DockerImage) AsRunScript(w io.Writer) error
• type DockerImageConfig
• type Dockerfile
  • func NewDockerfile(release OSRelease, img, password string, networkManager NetworkManager) (Dockerfile, error)
  • func (d Dockerfile) Render(w io.Writer) error
• type NetworkManager
  • func (n NetworkManager) Validate() error
• type OSRelease
  • func FetchDockerImageOSRelease(ctx context.Context, img string, tmpPath string) (OSRelease, error)
  • func ParseOSRelease(s string) (OSRelease, error)
• type Release
  • func (r Release) Supported() bool

Variables

var (
	Version   = ""
	BuildDate = ""
	Image     = ""
)

Functions

func Convert

func Convert(ctx context.Context, img string, opts ...ConvertOption) error

func MoveFile

func MoveFile(sourcePath, destPath string) error

func NewImage

func NewImage(ctx context.Context, tag string, imageTmpPath string) (*image, error)

func OutputFormats

func OutputFormats() []string

Types

type Builder

type Builder interface {
	Build(ctx context.Context) (err error)
	Close() error
}

func NewBuilder

func NewBuilder(ctx context.Context, workdir, imgTag, disk string, size int64, osRelease OSRelease, format string, cmdLineExtra string) (Builder, error)

type ConvertOption

type ConvertOption func(o *convertOptions)

func WithCmdLineExtra

func WithCmdLineExtra(cmdLineExtra string) ConvertOption

func WithNetworkManager

func WithNetworkManager(networkManager NetworkManager) ConvertOption

func WithOutput

func WithOutput(output string) ConvertOption

func WithPassword

func WithPassword(password string) ConvertOption

func WithRaw

func WithRaw(raw bool) ConvertOption

func WithSize

func WithSize(size int64) ConvertOption

type DockerImage

type DockerImage struct {
	DockerImageConfig `json:"Config"`
	Architecture      string `json:"Architecture"`
	Os                string `json:"Os"`
	Size              int    `json:"Size"`
}

func (DockerImage) AsRunScript

func (i DockerImage) AsRunScript(w io.Writer) error

type DockerImageConfig

type DockerImageConfig struct {
	Image      string   `json:"Image"`
	Hostname   string   `json:"Hostname"`
	Domainname string   `json:"Domainname"`
	User       string   `json:"User"`
	Env        []string `json:"Env"`
	Cmd        []string `json:"Cmd"`
	WorkingDir string   `json:"WorkingDir"`
	Entrypoint []string `json:"Entrypoint"`
}

type Dockerfile

type Dockerfile struct {
	Image          string
	Password       string
	Release        OSRelease
	NetworkManager NetworkManager
	// contains filtered or unexported fields
}

func NewDockerfile

func NewDockerfile(release OSRelease, img, password string, networkManager NetworkManager) (Dockerfile, error)

func (Dockerfile) Render

func (d Dockerfile) Render(w io.Writer) error

type NetworkManager

type NetworkManager string

const (
	NetworkManagerNone      NetworkManager = "none"
	NetworkManagerIfupdown2 NetworkManager = "ifupdown"
	NetworkManagerNetplan   NetworkManager = "netplan"
)

func (NetworkManager) Validate

func (n NetworkManager) Validate() error

type OSRelease

type OSRelease struct {
	ID              Release
	Name            string
	VersionID       string
	Version         string
	VersionCodeName string
}

func FetchDockerImageOSRelease

func FetchDockerImageOSRelease(ctx context.Context, img string, tmpPath string) (OSRelease, error)

func ParseOSRelease

func ParseOSRelease(s string) (OSRelease, error)

type Release

type Release string

const (
	ReleaseUbuntu Release = "ubuntu"
	ReleaseDebian Release = "debian"
	ReleaseAlpine Release = "alpine"
	ReleaseCentOS Release = "centos"
	ReleaseRHEL   Release = "rhel"
)

func (Release) Supported

func (r Release) Supported() bool