func NewLibvirtLXCBackend(state *State, portAlloc map[string]*ports.Allocator, volPath, logPath, initPath string) (Backend, error) {
	libvirtc, err := libvirt.NewVirConnection("lxc:///")
	if err != nil {
		return nil, err
	}

	iptables.RemoveExistingChain("FLYNN", "virbr0")
	chain, err := iptables.NewChain("FLYNN", "virbr0")
	if err != nil {
		return nil, err
	}
	if err := ioutil.WriteFile("/proc/sys/net/ipv4/conf/virbr0/route_localnet", []byte("1"), 0666); err != nil {
		return nil, err
	}
	if err := ioutil.WriteFile("/sys/class/net/virbr0/bridge/stp_state", []byte("0"), 0666); err != nil {
		return nil, err
	}

	return &LibvirtLXCBackend{
		LogPath:    logPath,
		VolPath:    volPath,
		InitPath:   initPath,
		libvirt:    libvirtc,
		state:      state,
		ports:      portAlloc,
		forwarder:  ports.NewForwarder(net.ParseIP("0.0.0.0"), chain),
		logs:       make(map[string]*logbuf.Log),
		containers: make(map[string]*libvirtContainer),
	}, nil
}
func NewLibvirtLXCBackend(state *State, portAlloc map[string]*ports.Allocator, volPath, logPath, initPath string) (Backend, error) {
	libvirtc, err := libvirt.NewVirConnection("lxc:///")
	if err != nil {
		return nil, err
	}

	pinkertonCtx, err := pinkerton.BuildContext("aufs", "/var/lib/docker")
	if err != nil {
		return nil, err
	}

	if err := writeResolvConf("/etc/flynn/resolv.conf"); err != nil {
		return nil, fmt.Errorf("Could not create resolv.conf: %s", err)
	}

	b := random.Bytes(5)
	bridgeMAC := fmt.Sprintf("fe:%02x:%02x:%02x:%02x:%02x", b[0], b[1], b[2], b[3], b[4])

	network, err := libvirtc.LookupNetworkByName(libvirtNetName)
	if err != nil {
		n := &lt.Network{
			Name:   libvirtNetName,
			Bridge: lt.Bridge{Name: bridgeName, STP: "off"},
			IP:     lt.IP{Address: bridgeAddr.String(), Netmask: bridgeMask},
			MAC:    lt.MAC{Address: bridgeMAC},
		}
		network, err = libvirtc.NetworkDefineXML(string(n.XML()))
		if err != nil {
			return nil, err
		}
	}
	active, err := network.IsActive()
	if err != nil {
		return nil, err
	}
	if !active {
		if err := network.Create(); err != nil {
			return nil, err
		}
	}
	// We need to explicitly assign the MAC address to avoid it changing to a lower value
	// See: https://github.com/flynn/flynn/issues/223
	if err := netlink.NetworkSetMacAddress(bridgeName, bridgeMAC); err != nil {
		return nil, err
	}

	iptables.RemoveExistingChain("FLYNN", bridgeName)
	chain, err := iptables.NewChain("FLYNN", bridgeName)
	if err != nil {
		return nil, err
	}
	if err := ioutil.WriteFile("/proc/sys/net/ipv4/conf/"+bridgeName+"/route_localnet", []byte("1"), 0666); err != nil {
		return nil, err
	}
	return &LibvirtLXCBackend{
		LogPath:    logPath,
		VolPath:    volPath,
		InitPath:   initPath,
		libvirt:    libvirtc,
		state:      state,
		ports:      portAlloc,
		pinkerton:  pinkertonCtx,
		forwarder:  ports.NewForwarder(net.ParseIP("0.0.0.0"), chain),
		logs:       make(map[string]*logbuf.Log),
		containers: make(map[string]*libvirtContainer),
	}, nil
}