nixpkgs/lib/build-vms.nix
Sander van der Burg 9c722e474d - 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
2010-10-21 22:50:12 +00:00

121 lines
4.1 KiB
Nix

{ nixpkgs, services, system, useBackdoor ? false }:
let pkgs = import nixpkgs { config = {}; inherit system; }; in
with pkgs;
with import ../lib/qemu-flags.nix;
rec {
inherit pkgs;
# Build a virtual network from an attribute set `{ machine1 =
# config1; ... machineN = configN; }', where `machineX' is the
# hostname and `configX' is a NixOS system configuration. The
# result is a script that starts a QEMU instance for each virtual
# machine. Each machine is given an arbitrary IP address in the
# virtual network.
buildVirtualNetwork =
{ nodes }:
let nodes_ = lib.mapAttrs (n: buildVM nodes_) (assignIPAddresses nodes); in
stdenv.mkDerivation {
name = "vms";
buildCommand =
''
ensureDir $out/vms
${
lib.concatMapStrings (vm:
''
ln -sn ${vm.config.system.build.vm} $out/vms/${vm.config.networking.hostName}
''
) (lib.attrValues nodes_)
}
ensureDir $out/bin
cat > $out/bin/run-vms <<EOF
#! ${stdenv.shell}
port=8080
for i in $out/vms/*; do
port2=\$((port++))
echo "forwarding localhost:\$port2 to \$(basename \$i):80"
QEMU_OPTS="-redir tcp:\$port2::80" \$i/bin/run-*-vm &
done
EOF
chmod +x $out/bin/run-vms
''; # */
passthru = { nodes = nodes_; };
};
buildVM =
nodes: configurations:
import ./eval-config.nix {
inherit nixpkgs services system;
modules = configurations ++
[ ../modules/virtualisation/qemu-vm.nix
../modules/testing/test-instrumentation.nix # !!! should only get added for automated test runs
{ key = "no-manual"; services.nixosManual.enable = false; virtualisation.useBackdoor = useBackdoor; }
];
extraArgs = { inherit nodes; };
};
# Given an attribute set { machine1 = config1; ... machineN =
# configN; }, sequentially assign IP addresses in the 192.168.1.0/24
# range to each machine, and set the hostname to the attribute name.
assignIPAddresses = nodes:
let
machines = lib.attrNames nodes;
machinesNumbered = lib.zipTwoLists machines (lib.range 1 254);
nodes_ = lib.flip map machinesNumbered (m: lib.nameValuePair m.first
[ ( { config, pkgs, nodes, ... }:
let
interfacesNumbered = lib.zipTwoLists config.virtualisation.vlans (lib.range 1 255);
interfaces =
lib.flip map interfacesNumbered ({ first, second }:
{ name = "eth${toString second}";
ipAddress = "192.168.${toString first}.${toString m.second}";
}
);
in
{ key = "ip-address";
config =
{ networking.hostName = m.first;
networking.interfaces = interfaces;
networking.primaryIPAddress =
lib.optionalString (interfaces != []) (lib.head interfaces).ipAddress;
# Put the IP addresses of all VMs in this machine's
# /etc/hosts file. If a machine has multiple
# interfaces, use the IP address corresponding to
# the first interface (i.e. the first network in its
# virtualisation.vlans option).
networking.extraHosts = lib.flip lib.concatMapStrings machines
(m: let config = (lib.getAttr m nodes).config; in
lib.optionalString (config.networking.primaryIPAddress != "")
("${config.networking.primaryIPAddress} " +
"${config.networking.hostName}\n"));
virtualisation.qemu.options =
lib.flip lib.concatMapStrings interfacesNumbered
({ first, second }: qemuNICFlags second first );
};
}
)
(lib.getAttr m.first nodes)
] );
in lib.listToAttrs nodes_;
}