QEMU in a docker container for running x64 virtual machines (even on ARM platforms).

It uses high-performance QEMU options (like KVM acceleration, kernel-mode networking, IO threading, etc.) to achieve near-native speed.

• Multi-platform
• KVM acceleration
• Web-based viewer

Via docker-compose.yml

version: "3"
services:
  qemu:
    container_name: qemu
    image: qemux/qemu-docker
    environment:
      BOOT: "https://dl-cdn.alpinelinux.org/alpine/v3.19/releases/x86_64/alpine-virt-3.19.0-x86_64.iso"
    devices:
      - /dev/kvm
    cap_add:
      - NET_ADMIN
    ports:
      - 8006:8006
    stop_grace_period: 2m
    restart: unless-stopped

Via docker run

docker run -it --rm -e "BOOT=https://example.com/image.iso" -p 8006:8006 --device=/dev/kvm --cap-add NET_ADMIN qemux/qemu-docker

• How do I use it?

  You begin by setting the BOOT environment variable to the URL of an ISO image of the OS you want to install:

  environment:
    BOOT: "https://dl-cdn.alpinelinux.org/alpine/v3.19/releases/x86_64/alpine-virt-3.19.0-x86_64.iso"

  Start the container and connect to port 8006 of the container in your web browser.

  After the download is finished, you will see the screen and can interact with it via the keyboard and mouse. Enjoy your new machine, and don't forget to star this repo!

• How do I increase the amount of CPU or RAM?

  By default, a single CPU core and 1 GB of RAM are allocated to the container.

  To increase this, add the following environment variables:

  environment:
    RAM_SIZE: "4G"
    CPU_CORES: "4"

• How do I change the size of the disk?

  To expand the default size of 16 GB, add the DISK_SIZE setting to your compose file and set it to your preferred capacity:

  environment:
    DISK_SIZE: "128G"

  This can also be used to resize the existing disk to a larger capacity without any data loss.

• How do I change the storage location?

  To change the storage location, include the following bind mount in your compose file:

  volumes:
    - /var/qemu:/storage

  Replace the example path /var/qemu with the desired storage folder.

• How do I boot Windows?

  For emulating Windows, there is dockur/windows, which is more dedicated to that purpose. It has all the same features as this container, but additionally includes all the necessary drivers, and it will even automatically download the correct ISO image from the Microsoft servers.

• How do I verify if my system supports KVM?

  To verify if your system supports KVM, run the following commands:

  sudo apt install cpu-checker
  sudo kvm-ok

  If you receive an error from kvm-ok indicating that KVM acceleration can't be used, check the virtualization settings in the BIOS.

• How do I assign an individual IP address to the container?

  By default, the container uses bridge networking, which shares the IP address with the host.

  If you want to assign an individual IP address to the container, you can create a macvlan network as follows:

  docker network create -d macvlan \
      --subnet=192.168.0.0/24 \
      --gateway=192.168.0.1 \
      --ip-range=192.168.0.100/28 \
      -o parent=eth0 vlan

  Be sure to modify these values to match your local subnet.

  Once you have created the network, change your compose file to look as follows:

  services:
    qemu:
      container_name: qemu
      ..<snip>..
      networks:
        vlan:
          ipv4_address: 192.168.0.100
  
  networks:
    vlan:
      external: true

  An added benefit of this approach is that you won't have to perform any port mapping anymore, since all ports will be exposed by default.

  Please note that this IP address won't be accessible from the Docker host due to the design of macvlan, which doesn't permit communication between the two. If this is a concern, you need to create a second macvlan as a workaround.

• How can the VM acquire an IP address from my router?

  After configuring the container for macvlan (see above), it is possible for the VM to become part of your home network by requesting an IP from your router, just like your other devices.

  To enable this feature, add the following lines to your compose file:

  environment:
    DHCP: "Y"
  device_cgroup_rules:
    - 'c *:* rwm'

  Please note that in this mode, the container and the VM will each have their own separate IPs. The container will keep the macvlan IP, and the VM will be reachable via the DHCP IP.

• How do I pass-through a disk?

  It is possible to pass-through disk devices directly by adding them to your compose file in this way:

  environment:
    DEVICE: "/dev/sda"
    DEVICE2: "/dev/sdb"
  devices:
    - /dev/sda
    - /dev/sdb

  Use DEVICE if you want it to become your main drive, and use DEVICE2 and higher to add them as secondary drives.

• How do I boot with UEFI?

  To enable UEFI booting, add the following line to your compose file:

  environment:
    BOOT_MODE: "uefi"

• How do I provide custom arguments to QEMU?

  You can create the ARGUMENTS environment variable to provide additional arguments to QEMU at runtime:

  environment:
    ARGUMENTS: "-device usb-tablet"