MicroVM.nix
A Nix Flake to build NixOS and run it on one of several Type-2
Hypervisors on NixOS/Linux. The project is intended to provide a more
isolated alternative to nixos-container
. You can either build and
run MicroVMs like Nix packages, or alternatively install them as
systemd services declaratively in your host's Nix Flake or
imperatively with the provided microvm
command.
Warning: This is a Nix Flakes-only project. Use with nix-shell -p nixFlakes
At a glance
- MicroVMs are Virtual Machines but use special device interfaces (virtio) for high performance
- This project runs them on NixOS hosts
- You can choose one of five hypervisors for each MicroVM
- MicroVMs have a fixed RAM allocation (default: 512 MB)
- MicroVMs have a read-only root disk with either a prepopulated
/nix/store
or by mounting the host's along with an optional writable overlay - You define your MicroVMs in a Nix Flake's
nixosConfigurations
section, reusing thenixosModules
that are exported by this Flake - MicroVMs can access stateful filesystems either on a image volume as a block device or as a shared directory hierarchy through 9p or virtiofs.
- Zero, one, or more virtual tap ethernet network interfaces can be attached to a MicroVM.
Hypervisors
Hypervisor | Language | Restrictions |
---|---|---|
qemu | C | |
cloud-hypervisor | Rust | no 9p shares |
firecracker | Rust | no 9p/virtiofs shares |
crosvm | Rust | no control socket |
kvmtool | C | no virtiofs shares, no control socket |
While ubiquitous qemu seems to work in most situations, other hypervisors tend to break with Linux kernel updates. Especially crosvm and kvmtool need a lot of luck to get going.
Installation
nix registry add microvm github:astro/microvm.nix
(If you do not want to inflict this change on your system, just
replace microvm
with github:astro/microvm.nix
in the following
examples.)
Start your own NixOS MicroVM definitions
nix flake init -t microvm
Examples
Run MicroVMs on your local machine
nix run microvm#qemu-example
nix run microvm#firecracker-example
nix run microvm#cloud-hypervisor-example
nix run microvm#crosvm-example
nix run microvm#kvmtool-example
Run a MicroVM example with nested MicroVMs on 5 different Hypervisors
nix run microvm#vm
Check networkctl status virbr0
for the DHCP leases of the
MicroVMs. They listen for ssh with an empty root password.
Commercial support
The author can be hired to implement the features that you wish, or to
integrate this tool into your toolchain. If in doubt, just press the