====================
 Running a MicroVM
====================

This guide walks through deploying demo-ops as a microVM on an existing
NixOS host using `microvm.nix <https://github.com/astro/microvm.nix>`_.
This is an alternative to the :doc:`QEMU approach <run-qemu-vm>` and
is useful when you already have a NixOS machine with spare capacity.


Prerequisites
=============

- Nix installed on your workstation
- A NixOS host prepared for microVMs — see
  :doc:`bo:kubernetes/microvm` for the required modules and host setup


Configuration
=============

Edit ``nixos/hosts/demo-single-node-microvm.nix``:

- Set the IP address and gateway for your network
- Set ``network.prefixLength`` if your subnet is not ``/24``
- Add your SSH public key
- Adjust the MAC address if needed

Edit ``ansible/inventory-microvm.yaml``:

- Set ``ansible_host`` to match the VM IP
- Set ``microvm_host`` to the hypervisor's IP


Deployment
==========

Enter the ansible development shell:

.. code-block:: bash

   nix develop ./external/business-operations#ansible

Deploy the microVM to the hypervisor host:

.. code-block:: bash

   ansible-playbook -i ./ansible/inventory-microvm.yaml \
     $BO_PLAYBOOKS/deploy-microvms.yaml

This builds the NixOS configuration, installs it on the hypervisor,
creates the volumes, and starts the VM.

Verify SSH access:

.. code-block:: bash

   ssh root@<vm-ip> hostname

Bootstrap the Kubernetes cluster:

.. code-block:: bash

   ansible-playbook -i ./ansible/inventory-microvm.yaml \
     $BO_PLAYBOOKS/bootstrap-existing-machines.yaml

Kick off FluxCD:

.. code-block:: bash

   ansible-playbook -i ./ansible/inventory-microvm.yaml \
     $BO_PLAYBOOKS/bootstrap-cluster.yaml


Result
======

You should have a single-node Kubernetes cluster running inside a
microVM, with Flux managing the applications.

See :doc:`first-login` for accessing the deployed applications.