Custom Notes

Installation in KASM

• Build image and use a custom-repo
• Docker Run Config Override:

  {
    "hostname": "kasm",
    "user": "root",
    "privileged": true,
    "environment": {
          "CPU_CORES": 1,
          "RAM_SIZE" : "4G",
          "DISK_SIZE": "16G",
          "BOOT" : "https://dl-cdn.alpinelinux.org/alpine/v3.19/releases/x86_64/alpine-virt-3.19.1-x86_64.iso"
      }
  }

  
  MAKE SURE THAT CPU_CORES AND RAM_SIZE DO NOT EXCEED THE WORKSPACELIMITS!

Recommendations:

• Pre-download your bootimage: Predownload your bootimage on your host, rename it to boot.iso and link it to the workspace via

  {
    "/mnt/path-to-your-directory": {
      "bind": "/storage",
      "mode": "rw",
      "uid": 1000,
      "gid": 1000,
      "required": true,
      "skip_check": false
    }
  }

  be advised: The image stores also it's disk at that location, so you will have your virtual harddrive up there!

Bugs and quirks

• You have to start a Terminal after container startup and run `/usr/bin/tini -s /run/entry.sh` otherwise the sound won't work...
• Right now - when you start the container, it takes a while for the VM to start. I've included a sleep 10-command to let it wait a bit, cause I've experienced problems without it. (on autostart - needs figuring out of the sound-problem first)
• I have to figure out how to boot directly from the disk after installing the VM-System...

Original-Docs:

QEMU

QEMU in a docker container for running x86 and x64 virtual machines.

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

Features

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

Usage

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-3.19.1-x86_64.iso"
    devices:
      - /dev/kvm
    cap_add:
      - NET_ADMIN
    ports:
      - 8006:8006
    stop_grace_period: 2m
    restart: on-failure

Via docker run

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

FAQ

• How do I use it?

  Very simple! These are the steps:

  • Set the BOOT environment variable to the URL of an ISO image you want to install.

  • Start the container and connect to port 8006 using your web browser.

  • You will see the screen and can now install the OS of your choice using your keyboard and mouse.

  Enjoy your brand 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 a local image?

  To skip the download, rename your image to boot.iso and place it in an empty /storage folder.

• 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 boot Windows?

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

  environment:
    BOOT_MODE: "windows"

  But you might want to give dockur/windows a try instead, as it includes all the drivers required during installation amongst many other features.

• How do I boot a ARM-based image?

  You can use qemu-arm to run ARM64 images.

• 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 a real PC.

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

  environment:
    DHCP: "Y"
  devices:
    - /dev/vhost-net
  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 use 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 pass-through a USB device?

  To pass-through a USB device, first lookup its vendor and product id via the lsusb command, then add them to your compose file like this:

  environment:
    ARGUMENTS: "-device usb-host,vendorid=0x1234,productid=0x1234"
  devices:
    - /dev/bus/usb

• 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 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"

Stars