- Added nixos-build-vms command, which builds a virtual network from a network.nix expression (also used by nixos-deploy-network)

- Added a backdoor option to the interactive run-vms script. This allows me to intergrate the virtual network approach with Disnix
- Small documentation fixes

Some explanation:

The nixos-build-vms command line tool can be used to build a virtual network of a network.nix specification.
For example, a network configuration (network.nix) could look like this:

{
  test1 = 
    {pkgs, config, ...}:
 
    {
      services.openssh.enable = true;
      ...
    };

  test2 =
    {pkgs, config, ...}:
    
    {
      services.openssh.enable = true;
      services.xserver.enable = true;
    }

    ;
}

By typing the following instruction:

$ nixos-build-vms -n network.nix

a virtual network is built, which can be started by typing:

$ ./result/bin/run-vms

It is also possible to enable a backdoor. In this case *.socket files are stored in the current directory
which can be used by the end-user to invoke remote instruction on a VM in the network through a Unix
domain socket.

For example by building the network with the following instructions:

$ nixos-build-vms -n network.nix --use-backdoor

and launching the virtual network:

$ ./result/bin/run-vms

You can find two socket files in your current directory, namely: test1.socket and test2.socket.
These Unix domain sockets can be used to remotely administer the test1 and test2 machine
in the virtual network.

For example by running:

$ socat ./test1.socket stdio
ls /root

You can retrieve the contents of the /root directory of the virtual machine with identifier test1


svn path=/nixos/trunk/; revision=24410

lib/build-vms.nix

@@ -1,4 +1,4 @@
-{ nixpkgs, services, system }:
+{ nixpkgs, services, system, useBackdoor ? false }:
 
 let pkgs = import nixpkgs { config = {}; inherit system; }; in
 
@@ -58,7 +58,7 @@ rec {
       modules = configurations ++
         [ ../modules/virtualisation/qemu-vm.nix
           ../modules/testing/test-instrumentation.nix # !!! should only get added for automated test runs
-          { key = "no-manual"; services.nixosManual.enable = false; }
+          { key = "no-manual"; services.nixosManual.enable = false; virtualisation.useBackdoor = useBackdoor; }
         ];
       extraArgs = { inherit nodes; };
     };