<refentry xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xi="http://www.w3.org/2001/XInclude"> <refmeta> <refentrytitle><command>nixos-build-vms</command></refentrytitle> <manvolnum>8</manvolnum> <refmiscinfo class="source">NixOS</refmiscinfo> <!-- <refmiscinfo class="version"><xi:include href="version.txt" parse="text"/></refmiscinfo> --> </refmeta> <refnamediv> <refname><command>nixos-build-vms</command></refname> <refpurpose>build a network of virtual machines from a network of NixOS configurations</refpurpose> </refnamediv> <refsynopsisdiv> <cmdsynopsis> <command>nixos-build-vms</command> <arg><option>--show-trace</option></arg> <arg><option>--no-out-link</option></arg> <arg><option>--help</option></arg> <arg choice="plain"><replaceable>network.nix</replaceable></arg> </cmdsynopsis> </refsynopsisdiv> <refsection><title>Description</title> <para>This command builds a network of QEMU-KVM virtual machines of a Nix expression specifying a network of NixOS machines. The virtual network can be started by executing the <filename>bin/run-vms</filename> shell script that is generated by this command. By default, a <filename>result</filename> symlink is produced that points to the generated virtual network. </para> <para>A network Nix expression has the following structure: <screen> { test1 = {pkgs, config, ...}: { services.openssh.enable = true; nixpkgs.system = "i686-linux"; deployment.targetHost = "test1.example.net"; # Other NixOS options }; test2 = {pkgs, config, ...}: { services.openssh.enable = true; services.httpd.enable = true; environment.systemPackages = [ pkgs.lynx ]; nixpkgs.system = "x86_64-linux"; deployment.targetHost = "test2.example.net"; # Other NixOS options }; } </screen> Each attribute in the expression represents a machine in the network (e.g. <varname>test1</varname> and <varname>test2</varname>) referring to a function defining a NixOS configuration. In each NixOS configuration, two attributes have a special meaning. The <varname>deployment.targetHost</varname> specifies the address (domain name or IP address) of the system which is used by <command>ssh</command> to perform remote deployment operations. The <varname>nixpkgs.system</varname> attribute can be used to specify an architecture for the target machine, such as <varname>i686-linux</varname> which builds a 32-bit NixOS configuration. Omitting this property will build the configuration for the same architecture as the host system. </para> </refsection> <refsection><title>Options</title> <para>This command accepts the following options:</para> <variablelist> <varlistentry> <term><option>--show-trace</option></term> <listitem> <para>Shows a trace of the output.</para> </listitem> </varlistentry> <varlistentry> <term><option>--no-out-link</option></term> <listitem> <para>Do not create a 'result' symlink.</para> </listitem> </varlistentry> <varlistentry> <term><option>-h</option>, <option>--help</option></term> <listitem> <para>Shows the usage of this command to the user.</para> </listitem> </varlistentry> </variablelist> </refsection> </refentry>