View source for FAQ/Bare Metal Deployment


Non-Nix bare metal deployments are typically maintained with a "converging" configuration manager like Puppet or Chef. NixOS's [https://nixos.org/nixos/manual/index.html#sec-writing-modules module system]
replaces these tools for per-host configuration mechanisms,
like declaring various services, monitoring options, and configuration
file contents. This makes the installation and configuration of your deployment fully declarative.

This module system can also be used to easily create virtual machines
equivalent to the finally deployed image. This VM can then be used to
run testing to ensure the service would behave as required.

Hydra is the Nix ecosystem's build server, which can provide a nice
breakdown of dependencies and more naturally (when compared to Jenkins
etc.) understands the robust build dependency tree inherent to Nix's
build model: [https://hydra.nixos.org/ https://hydra.nixos.org/] and
[https://github.com/nixos/hydra/ https://github.com/nixos/hydra/].

For example, this page tracks the specific tests required to pass
before a new version of NixOS is released:
[https://hydra.nixos.org/job/nixos/trunk-combined/tested#tabs-constituents https://hydra.nixos.org/job/nixos/trunk-combined/tested#tabs-constituents].

The VMs that are built from a machine's configuration can easily be
integrated with [https://nixos.org/nixos/manual/index.html#sec-nixos-tests NixOS's test infrastructure]
and Hydra to automatically verify package updates and system
configurations behave as expected.

These integration tests and builds can be robustly distributed across
a build fleet using [https://nix.dev/manual/nix/stable/advanced-topics/distributed-builds Nix's built in distributed build mechanism].
Unlike Jenkins and many other CI tools, the remote builders require no
additional setup or specific software installed, beyond the standard
Nix daemon configuration.


NixOps can be used to implement orchestration, though for dedicated
hardware is not yet capable of handling the provisioning step of the
hardware.

Handling initial hardware intake and burn-in would need to be handled
separately, however NixOS's support for generating PXE images should
make this not too difficult.

Kickstart's disk provisioning portion doesn't have an equal in the
NixOS ecosystem, however can be accomplished using PXE-boot images and
auto-run boot up phases which run disk formatting steps. For some
prior work, check out [https://github.com/grahamc/packet-provision-nixos-ipxe/ https://github.com/grahamc/packet-provision-nixos-ipxe/].
The parts around system configuration and package installation is
completely and thoroughly covered by the module system and system
configuration options that exist.