NixOS Containers

NixOS containers are lightweight systemd-nspawn containers managed declaratively through your NixOS configuration. They allow you to run separate, minimal NixOS instances on the same machine, each with its own services, packages, and (optionally) network stack.

Common Use Cases

• Isolating services: Run a web server, database, or any service in its own container, so it can’t interfere with the main system or other services

• Testing and development: Try out new configurations, packages, or services in a sandboxed environment.

• Reproducible deployments: Because containers are defined declaratively, you can reproduce the exact same environment anywhere.

• Running multiple versions of a service: For example, testing different versions of Git or HTTP servers side by side.

Hosting an mdBook or Offline Git Server

Let’s say you want to host your mdBook or run a Git server for offline use. You can define a NixOS container that runs only the necessary service, isolated from your main system:

containers.mdbook = {
  ephemeral = true;         # Container resets on restart (optional)
  autoStart = true;         # Starts automatically at boot
  config = { config, pkgs, ... }: {
    # Example: Serve static files with httpd (Apache)
    services.httpd.enable = true;
    services.httpd.adminAddr = "you@example.org";
    networking.firewall.allowedTCPPorts = [ 80 ];
    # You could also use nginx, or run the mdbook server directly
    # Or, for a git server:
    # services.gitDaemon.enable = true;
  };
};

• ephemeral: if true, the container resets on each restart.

• autoStart: Ensures the container starts automatically at boot.

• config: Defines the containers NixOS configuration, just like a regular NixOS system.