Running Home Assistant OS as a VM in a NixOS Host

Introduction

I have a “smart” home. I like NixOS. Configuring things is fun. Also, my previous Proxmox host, which used to house my Home Assistant VM, is being repurposed for Windows Server, and I don’t feel like putting Home Assistant on one of my Raspberry Pis because that would just make too much sense (I might end up doing this later anyway).

Now that I’ve moved my NAS to NixOS, I want to fully utilize the remaining available resources, so a Home Assistant migration was in order. I chose Incus as my “we have Proxmox at home” “Proxmox-lite” solution as it seems to be decently supported and has a graphical web front-end to make management easier. Trouble is, I’ve never used Incus before, and getting Home Assistant OS in a Proxmox VM to work was as easy as running a helpful pre-made script.

There’s tutorials for Incus on NixOS. There’s tutorials for Home Assistant on Incus. This one is for both. I’m assuming you’re already familiar with NixOS and flakes.

Heavily leveraging the work done by Scotti-Byte in the following tutorials:

The final setup provides:

  • HomeAssistant OS running in an Incus VM
  • VM gets its own IP from your router’s DHCP
  • Optimal device discovery for IoT integration
  • Clean, declarative NixOS configuration
  • ZFS storage integration

System Overview

Hardware Setup

  • Host: HP MicroServer Gen8 (16GB RAM, x86_64)
  • Storage: ZFS root pool on 500GB SSD + ZFS data pool on 4x4TB drives
  • Network: Single ethernet interface with bridge networking
  • OS: NixOS with Incus virtualization

Architecture

[Router DHCP] ←→ [Physical Network] ←→ [eno1] ←→ [br0 Bridge] ←→ [VM]
                                              ↑
                                        [Host also gets IP]

Both the NixOS host and HomeAssistant VM get separate IP addresses from the same router, appearing as independent devices on the network.

NixOS Configuration

Step 1: Enable Incus with ZFS Storage

Skip the ZFS part if you aren’t using ZFS, but define a storage pool somewhere.

# In hosts/linux-nas/default.nix
virtualisation = {
  # Incus virtualization
  incus = {
    enable = true;
    ui.enable = true;  # Enable web UI
    preseed = {
      networks = [
        {
          name = "incusbr0";
          type = "bridge";
          config = {
            "ipv4.address" = "10.0.100.1/24";
            "ipv4.nat" = "true";
          };
        }
      ];
      storage_pools = [
        {
          name = "zfs-incus";
          driver = "zfs";
          config = {
            source = "rpool/incus";  # Use existing ZFS dataset
          };
        }
      ];
      profiles = [
        {
          name = "default";
          devices = {
            eth0 = {
              name = "eth0";
              network = "incusbr0";
              type = "nic";
            };
            root = {
              path = "/";
              pool = "zfs-incus";
              type = "disk";
            };
          };
        }
      ];
    };
  };

  # Also enable libvirtd for virt-manager
  libvirtd = {
    enable = true;
    qemu = {
      package = pkgs.qemu_kvm;
      ovmf.enable = true;
      ovmf.packages = [ pkgs.OVMF ];
    };
  };
};

Step 2: Configure Bridge Networking

Using NixOS’s native bridge support instead of fighting with NetworkManager:

networking = {
  # Disable NetworkManager in favor of simple bridge configuration
  networkmanager.enable = false;
  # Use systemd-networkd for bridge management
  useNetworkd = true;
  # Required for Incus networking
  nftables.enable = true;
  # Disable firewall for simplified setup (local network only)
  firewall.enable = false;

  # Create bridge interface with NixOS
  bridges.br0 = {
    interfaces = [ "eno1" ];  # Your ethernet interface
  };

  # Configure bridge with DHCP
  interfaces.br0 = {
    useDHCP = true;
  };
};

This configuration:

  • Creates a br0 bridge that includes your physical ethernet interface
  • Gets an IP address via DHCP from your router
  • Provides a stable bridge that Incus can reference
  • Eliminates NetworkManager conflicts

I prefer setting DHCP and having my router statically assign an IP on its end. Your choice.

Step 3: User Permissions

users.users.${myvars.user.username} = {
  extraGroups = [
    # ... existing groups ...
    "incus-admin"  # Access to Incus management
    "libvirtd"     # Access to libvirt
  ];
};

Step 4: Install Virtualization Packages

environment.systemPackages = with pkgs; [
  # Virtualization packages
  qemu_kvm         # QEMU with KVM support
  virt-manager     # GUI for VM management
  libvirt          # libvirt client tools
  bridge-utils     # Network bridge utilities
];

You can choose to load these tools into an ephemeral shell with nix-shell -p if you want. They are for converting the HA OS image in this tutorial. I wanted to keep them for the future so I made them part of my system configuration.

Deployment and VM Creation

Deploy the Configuration

# Test the configuration
nix flake check

# Deploy to your NixOS host
nixos-rebuild switch --flake .#linux-nas

Create Bridged Profile

After deployment, create an Incus profile that uses the host bridge:

# On your NixOS host

# Create bridged profile that uses host br0 bridge directly
incus profile create bridgeprofile

# Add network device connected directly to host bridge
incus profile device add bridgeprofile eth0 nic \
  nictype=bridged \
  parent=br0 \
  name=eth0

Download and Import HomeAssistant OS

# Download "QEMU-friendly" HomeAssistant OS VM image
wget https://github.com/home-assistant/operating-system/releases/download/15.2/haos_ova-15.2.qcow2.xz

# Extract the image
xz -d "haos_ova-15.2.qcow2.xz"

# Get incus-migrate
wget https://github.com/lxc/incus/releases/latest/download/bin.linux.incus-migrate.x86_64
mv bin.linux.incus-migrate.x86_64 incus-migrate && chmod +x incus-migrate
./incus-migrate

Follow the prompts (reference Home Assistant OS in Incus 101):

  1. Yes (local Incus server target)
  2. 2 (Virtual Machine)
  3. HA-OS (name of the new instance, name it whatever you like)
  4. haos_ova-15.2.qcow2 (path to image file)
  5. Yes (UEFI booting)
  6. No (Secure booting)
  7. 2 (additional override profile list)
  8. default bridgeprofile (to have an address on the main LAN)
  9. 1 (perform the migration)

Here, I decided on setting the disk size and memory allocation:

incus config device override HA-OS root size=50GiB   
incus config set HA-OS limits.memory 4GiB

Launch HomeAssistant VM

incus start HA-OS
# Check VM status
incus list

Verification and Access

Check Network Configuration

# Verify host bridge has IP
ip addr show br0

# Verify VM has different IP from same network
incus list

Example output:

# Host bridge
br0: inet 192.168.1.100/24

# VM
homeassistant    192.168.1.150    RUNNING

Access HomeAssistant

  1. Wait for boot: HomeAssistant OS takes 5-10 minutes to initialize
  2. Access web interface: http://your-host-ip:8123
  3. Complete setup wizard: Create admin user and configure

Verify Device Discovery

The VM should now be able to:

  • Discover IoT devices on your local network
  • Be accessible from other devices on your network
  • Function as if it were a physical HomeAssistant device

Key Benefits

Network Integration

  • Separate IP address: VM appears as independent device
  • Device discovery: HomeAssistant can find IoT devices
  • Direct access: Other devices can reach HomeAssistant directly
  • Router DHCP: Uses existing network infrastructure

Management

  • Incus web UI: Manage VMs through browser interface
  • NixOS integration: Declarative configuration
  • Clean networking: No complex NetworkManager conflicts
  • Simple maintenance: Standard Incus and NixOS tools

Troubleshooting

VM Network Issues

# Check bridge status
brctl show br0

# Verify Incus profile
incus profile show bridgeprofile

# Check VM network interface
incus exec homeassistant -- ip addr show

Access Incus Web UI

Access the management interface at https://your-host-ip:8443

Performance Tuning

  • CPU: Start with 2 vCPUs, increase if needed
  • Memory: 4GB is sufficient for most setups; Scotty went with 6.
  • Disk: 32GB handles HomeAssistant + add-ons; I went with 50 GB just in case.

Conclusion

This setup provides a production-ready HomeAssistant environment that:

  • Leverages NixOS’s declarative configuration
  • Uses reliable ZFS storage
  • Provides optimal network integration
  • Supports the full HomeAssistant ecosystem

The result is a HomeAssistant VM that behaves exactly like a dedicated hardware device, on Incus and NixOS.