qemu

Documentation on the QEMU container

Run QEMU in containers using common cloud interfaces like cloud-init

This container comes with everything you need to run cloud-like virtual machines using QEMU in a container:

  • DNSMASQ, for custom DNS resolution
  • genisoimage, for creating ISOs for cloud-init
  • OVMF, for UEFI VMs
  • Python3, for running a simple HTTP webservice for cloud-init
  • QEMU, for running aarch64, arm, and x86 VMs
  • TPM, for emulating TPMs

The container is currently hosted on GitHub: https://github.com/orgs/candiddev/packages/container/package/qemu.

Environment Variables

  • ARCH The QEMU arch to emulate. Valid values are amd64, arm, and arm64. Default: amd64
  • BIOS If set to a value, will enable BIOS boot. Default: UEFI boot.
  • DNSMASQARGS Arguments to pass to DNSMASQ. Setting this will enable DNSMASQ. Requires NET_ADMIN capability. Default: "".
  • MEMORY The amount of memory to allocate to the VM. Default: 2G
  • QEMUARGS Arguments to pass to QEMU. Default: ""
  • SERIALPORT Set the serial port TCP listener. Setting this to "" will disable it. Default: 23
  • SMBIOS Inject data into the VM using SMBIOS/DMI type 11.
  • SMP The number of CPUs to assign to the VM. Default: 2
  • TPM Setting this to an empty string (-e TPM="") will disable the TPM.
  • WEBDIR The path to a webdir to expose via python HTTP. Setting this to an empty string (-e WEBDIR="") will disable python HTTP. Default: /cloudinit

Usage Examples

docker run $(if [[ -e /dev/kvm ]]; then echo "--device /dev/kvm"; fi) \
  -e ARCH=amd64 \
  -e DNSMASQARGS="-A /metadata.google.internal/169.254.169.254" \
  -e QEMUARGS="-drive file=/work/disk.raw,if=virtio,media=disk,format=qcow2,cache=none,index=0 -drive file=/work/cidata.iso,media=cdrom,if=virtio,index=1 -nic user,hostfwd=tcp::22-:22" \
  -d \
  --cap-add=NET_ADMIN \
  -p 22 \
  -p 23 \
  -v /work:/work \
  -v /cloudinit:/cloudinit \
  ghcr.io/candiddev/qemu:latest

This example will:

  • Mount /dev/kvm into the container if it’s available
  • Setup a DNSMASQ entry for metadata.google.internal (for emulating a Google Cloud metadata response)
  • Have QEMU boot a disk.raw file and mount a cidata ISO as a cdrom
  • Have QEMU attach a NIC using user mode networking and forward port 22
  • Add the NET_ADMIN capability so the container can add the 169.254.169.254 IP to its localhost for metadata servers
  • Expose port 22 (VM SSH)
  • Expose port 23 (serial connection, use nc ::1 <port> to connect to it)