nixpkgs/nixos/doc/manual/administration/containers.xml

<chapter xmlns="http://docbook.org/ns/docbook"
        xmlns:xlink="http://www.w3.org/1999/xlink"
        xmlns:xi="http://www.w3.org/2001/XInclude"
        version="5.0"
        xml:id="ch-containers">
 <title>Container Management</title>
 <para>
  NixOS allows you to easily run other NixOS instances as
  <emphasis>containers</emphasis>. Containers are a light-weight approach to
  virtualisation that runs software in the container at the same speed as in
  the host system. NixOS containers share the Nix store of the host, making
  container creation very efficient.
 </para>
 <warning>
  <para>
   Currently, NixOS containers are not perfectly isolated from the host system.
   This means that a user with root access to the container can do things that
   affect the host. So you should not give container root access to untrusted
   users.
  </para>
 </warning>
 <para>
  NixOS containers can be created in two ways: imperatively, using the command
  <command>nixos-container</command>, and declaratively, by specifying them in
  your <filename>configuration.nix</filename>. The declarative approach implies
  that containers get upgraded along with your host system when you run
  <command>nixos-rebuild</command>, which is often not what you want. By
  contrast, in the imperative approach, containers are configured and updated
  independently from the host system.
 </para>
 <xi:include href="imperative-containers.xml" />
 <xi:include href="declarative-containers.xml" />
 <xi:include href="container-networking.xml" />
</chapter>