- 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

modules/installer/tools/nixos-build-vms/nixos-build-vms.sh

@@ -0,0 +1,66 @@
+#! @shell@ -e
+
+# Shows the usage of this command to the user
+
+showUsage()
+{
+    echo "Usage: $0 -n network_expr -i infrastructure_expr"
+    echo "Options:"
+    echo
+    echo "-n,--network        Network Nix expression which captures properties of machines in the network"
+    echo "--use-backdoor      Indicates that the backdoor must be enabled so that the VMs can be accessed through a UNIX domain socket" 
+    echo "--show-trace        Shows the output trace"
+    echo "-h,--help           Shows the usage of this command"
+}
+
+# Parse valid argument options
+
+PARAMS=`getopt -n $0 -o n:h -l network:,use-backdoor,show-trace,help -- "$@"`
+
+if [ $? != 0 ]
+then
+    showUsage
+    exit 1
+fi
+
+eval set -- "$PARAMS"
+
+# Evaluate valid options
+
+while [ "$1" != "--" ]
+do
+    case "$1" in
+	-n|--network)
+	    networkExpr=`readlink -f $2`
+	    ;;
+	--use-backdoor)
+	    useBackdoorArg="--arg useBackdoor true"
+	    ;;
+	--show-trace)
+	    showTraceArg="--show-trace"
+	    ;;
+	-h|--help)
+	    showUsage
+	    exit 0
+	    ;;
+    esac
+    
+    shift
+done
+
+# Validate the given options
+
+if [ "$networkExpr" = "" ]
+then
+    echo "ERROR: A network expression must be specified!" >&2
+    exit 1
+fi
+
+if [ -z "$NIXOS" ]
+then
+    NIXOS=/etc/nixos/nixos
+fi
+
+# Build a network of VMs
+
+nix-build $NIXOS/modules/installer/tools/nixos-build-vms/build-vms.nix --argstr networkExpr $networkExpr --argstr nixos $NIXOS --argstr nixpkgs $NIXPKGS_ALL $useBackdoorArg $showTraceArg