pxeboot.write

#!/usr/bin/env python


import collections
import contextlib
import errno
import itertools
import logging
import os
import select
import signal
import shutil
import socket
import string
import StringIO
import subprocess
import sys
import tempfile
import textwrap
import urlparse

import cliapp

import morphlib


def _int_to_quad_dot(i):
    return '.'.join((
        str(i >> 24 & 0xff),
        str(i >> 16 & 0xff),
        str(i >> 8 & 0xff),
        str(i & 0xff)))


def _quad_dot_to_int(s):
    i = 0
    for octet in s.split('.'):
        i <<= 8
        i += int(octet, 10)
    return i


def _netmask_to_prefixlen(mask):
    bs = '{:032b}'.format(mask)
    prefix = bs.rstrip('0')
    if '0' in prefix:
        raise ValueError('abnormal netmask: %s' %
                         _int_to_quad_dot(mask))
    return len(prefix)


def _get_routes():
    routes = []
    with open('/proc/net/route', 'r') as f:
        for line in list(f)[1:]:
            fields = line.split()
            destination, flags, mask = fields[1], fields[3], fields[7]
            flags = int(flags, 16)
            if flags & 2:
                # default route, ignore
                continue
            destination = socket.ntohl(int(destination, 16))
            mask = socket.ntohl(int(mask, 16))
            prefixlen = _netmask_to_prefixlen(mask)
            routes.append((destination, prefixlen))
    return routes


class IPRange(object):
    def __init__(self, prefix, prefixlen):
        self.prefixlen = prefixlen
        mask = (1 << prefixlen) - 1
        self.mask = mask << (32 - prefixlen)
        self.prefix = prefix & self.mask
    @property
    def bitstring(self):
        return ('{:08b}' * 4).format(
            self.prefix >> 24 & 0xff,
            self.prefix >> 16 & 0xff,
            self.prefix >> 8 & 0xff,
            self.prefix & 0xff
        )[:self.prefixlen]
    def startswith(self, other_range):
        return self.bitstring.startswith(other_range.bitstring)


def find_subnet(valid_ranges, invalid_ranges):
    for vr in valid_ranges:
        known_subnets = set(ir for ir in invalid_ranges if ir.startswith(vr))
        prefixlens = set(r.prefixlen for r in known_subnets)
        prefixlens.add(32 - 2) # need at least 4 addresses in subnet
        prefixlen = min(prefixlens)
        if prefixlen <= vr.prefixlen:
            # valid subnet is full, move on to next
            continue
        subnetlen = prefixlen - vr.prefixlen
        for prefix in (subnetid + vr.prefix
                       for subnetid in xrange(1 << subnetlen)):
            if any(subnet.prefix == prefix for subnet in known_subnets):
                continue
            return prefix, prefixlen


def _normalise_macaddr(macaddr):
    '''pxelinux.0 wants the mac address to be lowercase and - separated'''
    digits = (c for c in macaddr.lower() if c in string.hexdigits)
    nibble_pairs = grouper(digits, 2)
    return '-'.join(''.join(byte) for byte in nibble_pairs)


@contextlib.contextmanager
def executor(target_pid):
    'Kills a process if its parent dies'
    read_fd, write_fd = os.pipe()
    helper_pid = os.fork()
    if helper_pid == 0:
        try:
            os.close(write_fd)
            while True:
                rlist, _, _ = select.select([read_fd], [], [])
                if read_fd in rlist:
                    d = os.read(read_fd, 1)
                    if not d:
                        os.kill(target_pid, signal.SIGKILL)
                    if d in ('', 'Q'):
                        os._exit(0)
                    else:
                        os._exit(1)
        except BaseException as e:
            import traceback
            traceback.print_exc()
            os._exit(1)
    os.close(read_fd)
    yield
    os.write(write_fd, 'Q')
    os.close(write_fd)


def grouper(iterable, n, fillvalue=None):
    "Collect data into fixed-length chunks or blocks"
    # grouper('ABCDEFG', 3, 'x') --> ABC DEF Gxx"
    args = [iter(iterable)] * n
    return itertools.izip_longest(*args, fillvalue=fillvalue)


class PXEBoot(morphlib.writeexts.WriteExtension):
    @contextlib.contextmanager
    def _vlan(self, interface, vlan):
        viface = '%s.%s' % (interface, vlan)
        self.status(msg='Creating vlan %(viface)s', viface=viface)
        subprocess.check_call(['vconfig', 'add', interface, str(vlan)])
        try:
            yield viface
        finally:
            self.status(msg='Destroying vlan %(viface)s', viface=viface)
            subprocess.call(['vconfig', 'rem', viface])

    @contextlib.contextmanager
    def _static_ip(self, iface):
        valid_ranges = set((
            IPRange(_quad_dot_to_int('192.168.0.0'), 16),
            IPRange(_quad_dot_to_int('172.16.0.0'), 12),
            IPRange(_quad_dot_to_int('10.0.0.0'), 8),
        ))
        invalid_ranges = set(IPRange(prefix, prefixlen)
                             for (prefix, prefixlen) in _get_routes())
        prefix, prefixlen = find_subnet(valid_ranges, invalid_ranges)
        netaddr = prefix
        dhcp_server_ip = netaddr + 1
        client_ip = netaddr + 2
        broadcast_ip = prefix | ((1 << (32 - prefixlen)) - 1)
        self.status(msg='Assigning ip address %(ip)s/%(prefixlen)d to '
                        'iface %(iface)s',
                    ip=_int_to_quad_dot(dhcp_server_ip), prefixlen=prefixlen,
                    iface=iface)
        subprocess.check_call(['ip', 'addr', 'add',
                               '{}/{}'.format(_int_to_quad_dot(dhcp_server_ip),
                                              prefixlen),
                               'broadcast', _int_to_quad_dot(broadcast_ip),
                               'scope', 'global',
                               'dev', iface])
        try:
            yield (dhcp_server_ip, client_ip, broadcast_ip)
        finally:
            self.status(msg='Removing ip addresses from iface %(iface)s',
                        iface=iface)
            subprocess.call(['ip', 'addr', 'flush', 'dev', iface])

    @contextlib.contextmanager
    def _up_interface(self, iface):
        self.status(msg='Bringing interface %(iface)s up', iface=iface)
        subprocess.check_call(['ip', 'link', 'set', iface, 'up'])
        try:
            yield
        finally:
            self.status(msg='Bringing interface %(iface)s down', iface=iface)
            subprocess.call(['ip', 'link', 'set', iface, 'down'])

    @contextlib.contextmanager
    def static_ip(self, interface):
        with self._static_ip(iface=interface) as (host_ip, client_ip,
                        broadcast_ip), \
             self._up_interface(iface=interface):
            yield (_int_to_quad_dot(host_ip),
                   _int_to_quad_dot(client_ip),
                   _int_to_quad_dot(broadcast_ip))

    @contextlib.contextmanager
    def vlan(self, interface, vlan):
        with self._vlan(interface=interface, vlan=vlan) as viface, \
             self.static_ip(interface=viface) \
                 as (host_ip, client_ip, broadcast_ip):
            yield host_ip, client_ip, broadcast_ip

    @contextlib.contextmanager
    def _tempdir(self):
        td = tempfile.mkdtemp()
        print 'Created tempdir:', td
        try:
            yield td
        finally:
            shutil.rmtree(td, ignore_errors=True)

    @contextlib.contextmanager
    def _remote_tempdir(self, hostname, template):
        td = cliapp.ssh_runcmd(hostname, ['mktemp', '-d', template]).strip()
        try:
            yield td
        finally:
            cliapp.ssh_runcmd(hostname, ['find', td, '-delete'])

    def _serve_tftpd(self, sock, host, port, interface, tftproot):
        self.settings.progname = 'tftp server'
        self._set_process_name()
        while True:
            logging.debug('tftpd waiting for connections')
            # recvfrom with MSG_PEEK is how you accept UDP connections
            _, peer = sock.recvfrom(0, socket.MSG_PEEK)
            conn = sock
            logging.debug('Connecting socket to peer: ' + repr(peer))
            conn.connect(peer)
            # The existing socket is now only serving that peer, so we need to
            # bind a new UDP socket to the wildcard address, which needs the
            # port to be in REUSEADDR mode.
            conn.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
            sock = socket.socket(family=socket.AF_INET, type=socket.SOCK_DGRAM)
            sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
            logging.debug('Binding replacement socket to ' + repr((host, port)))
            sock.bind((host, port))

            logging.debug('tftpd server handing connection to tftpd')
            tftpd_serve = ['tftpd', '-rl', tftproot]
            ret = subprocess.call(args=tftpd_serve, stdin=conn,
                                  stdout=conn, stderr=None, close_fds=True)
            # It's handy to turn off REUSEADDR after the rebinding,
            # so we can protect against future bind attempts on this port.
            sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 0)
            logging.debug('tftpd exited %d' % ret)
        os._exit(0)

    @contextlib.contextmanager
    def _spawned_tftp_server(self, tftproot, host_ip, interface, tftp_port=0):
        # inetd-style launchers tend to bind UDP ports with SO_REUSEADDR,
        # because they need to have multiple ports bound, one for recieving
        # all connection attempts on that port, and one for each concurrent
        # connection with a peer
        # this makes detecting whether there's a tftpd running difficult, so
        # we'll instead use an ephemeral port and configure the PXE boot to
        # use that tftp server for the kernel
        s = socket.socket(family=socket.AF_INET, type=socket.SOCK_DGRAM)
        s.bind((host_ip, tftp_port))
        host, port = s.getsockname()
        self.status(msg='Bound listen socket to %(host)s, %(port)s',
                    host=host, port=port)
        pid = os.fork()
        if pid == 0:
            try:
                self._serve_tftpd(sock=s, host=host, port=port,
                                  interface=interface, tftproot=tftproot)
            except BaseException as e:
                import traceback
                traceback.print_exc()
                os._exit(1)
        s.close()
        with executor(pid):
            try:
                yield port
            finally:
                self.status(msg='Killing tftpd listener pid=%(pid)d',
                            pid=pid)
                os.kill(pid, signal.SIGKILL)

    @contextlib.contextmanager
    def tftp_server(self, host_ip, interface, tftp_port=0):
        with self._tempdir() as tftproot, \
             self._spawned_tftp_server(tftproot=tftproot, host_ip=host_ip,
                                       interface=interface,
                                       tftp_port=tftp_port) as tftp_port:
            self.status(msg='Serving tftp root %(tftproot)s, on port %(port)d',
                        port=tftp_port, tftproot=tftproot)
            yield tftp_port, tftproot

    @contextlib.contextmanager
    def _local_copy(self, src, dst):
        self.status(msg='Installing %(src)s to %(dst)s',
                    src=src, dst=dst)
        shutil.copy2(src=src, dst=dst)
        try:
            yield
        finally:
            self.status(msg='Removing %(dst)s', dst=dst)
            os.unlink(dst)

    def local_pxelinux(self, tftproot):
        return self._local_copy('/usr/share/syslinux/pxelinux.0',
                                os.path.join(tftproot, 'pxelinux.0'))

    def local_kernel(self, rootfs, tftproot):
        return self._local_copy(os.path.join(rootfs, 'boot/vmlinuz'),
                                os.path.join(tftproot, 'kernel'))

    @contextlib.contextmanager
    def _remote_copy(self, hostname, src, dst):
        with open(src, 'r') as f:
            cliapp.ssh_runcmd(hostname,
                              ['install', '-D', '-m644', '/proc/self/fd/0',
                               dst], stdin=f, stdout=None, stderr=None)
        try:
            yield
        finally:
            cliapp.ssh_runcmd(hostname, ['rm', dst])

    @contextlib.contextmanager
    def remote_kernel(self, rootfs, tftp_url, macaddr):
        for name in ('vmlinuz', 'zImage', 'uImage'):
            kernel_path = os.path.join(rootfs, 'boot', name)
            if os.path.exists(kernel_path):
                break
        else:
            raise cliapp.AppException('Failed to locate kernel')
        url = urlparse.urlsplit(tftp_url)
        basename = '{}-kernel'.format(_normalise_macaddr(macaddr))
        target_path = os.path.join(url.path, basename)
        with self._remote_copy(hostname=url.hostname, src=kernel_path,
                               dst=target_path):
            yield basename

    @contextlib.contextmanager
    def local_nfsroot(self, rootfs, target_ip):
        nfsroot = target_ip + ':' + rootfs
        self.status(msg='Exporting %(nfsroot)s as local nfsroot',
                    nfsroot=nfsroot)
        cliapp.runcmd(['exportfs', '-o', 'ro,insecure,no_root_squash',
                       nfsroot])
        try:
            yield
        finally:
            self.status(msg='Removing %(nfsroot)s from local nfsroots',
                        nfsroot=nfsroot)
            cliapp.runcmd(['exportfs', '-u', nfsroot])

    @contextlib.contextmanager
    def remote_nfsroot(self, rootfs, rsync_url, macaddr):
        url = urlparse.urlsplit(rsync_url)
        template = os.path.join(url.path, 'nfsroot.XXXXXXXXXX')
        with self._remote_tempdir(hostname=url.hostname, template=template) \
                 as tempdir:
            nfsroot = urlparse.urlunsplit(url.scheme, url.netloc, tempdir,
                                          url.query, url.fragment)
            cliapp.runcmd(['rsync', '-asXSPH', '--delete', rootfs, nfsroot],
                          stdin=None, stdout=None, stderr=None)
            yield basename

    @staticmethod
    def _write_pxe_config(fh, kernel_tftp_url, rootfs_nfs_url, extra_args=''):
        fh.write(textwrap.dedent('''\
            DEFAULT default
            LABEL default
            LINUX {kernel_url}
            APPEND root=/dev/nfs ip=dhcp nfsroot={rootfs_nfs_url} {extra_args}
            ''').format(kernel_url=kernel_tftp_url,
                        rootfs_nfs_url=rootfs_nfs_url, extra_args=extra_args))
        fh.flush()

    @contextlib.contextmanager
    def local_pxeboot_config(self, tftproot, macaddr, ip, tftp_port,
                             nfsroot_dir):
        kernel_tftp_url = 'tftp://{}:{}/kernel'.format(ip, tftp_port)
        rootfs_nfs_url = '{}:{}'.format(ip, nfsroot_dir)
        pxe_cfg_filename = _normalise_macaddr(macaddr)
        pxe_cfg_path = os.path.join(tftproot, 'pxelinux.cfg', pxe_cfg_filename)
        os.makedirs(os.path.dirname(pxe_cfg_path))
        with open(pxe_cfg_path, 'w') as f:
            self._write_pxe_config(fh=f, kernel_tftp_url=kernel_tftp_url,
                                   rootfs_nfs_url=rootfs_nfs_url,
                                   extra_args=os.environ.get('KERNEL_ARGS',''))
        try:
            yield
        finally:
            os.unlink(pxe_cfg_path)

    @contextlib.contextmanager
    def remote_pxeboot_config(self, tftproot, kernel_tftproot, kernel_subpath,
                              rootfs_nfsroot, rootfs_subpath, macaddr):
        rootfs_nfs_url = '{}:{}/{}'.format(ip, rootfs_nfsroot, rootfs_subpath)
        kernel_tftp_url = '{}/{}'.format(kernel_tftproot, kernel_subpath)
        pxe_cfg_filename = _normalise_macaddr(macaddr)
        url = urlparse.urlsplit(tftproot)
        inst_cfg_path = os.path.join(url.path, 'pxelinux.cfg',
                                     pxe_cfg_filename)
        with tempfile.NamedTemporaryFile() as f:
            self._write_pxe_config(fh=f, kernel_tftp_url=kernel_tftp_url,
                                   rootfs_nfs_url=rootfs_nfs_url,
                                   extra_args=os.environ.get('KERNEL_ARGS',''))
            with self._remote_copy(hostname=url.hostname, src=f.name,
                                   dst=inst_cfg_path):
                yield

    @contextlib.contextmanager
    def dhcp_server(self, interface, host_ip, target_ip, broadcast_ip):
        with self._tempdir() as td:
            leases_path = os.path.join(td, 'leases')
            config_path = os.path.join(td, 'config')
            stdout_path = os.path.join(td, 'stdout')
            stderr_path = os.path.join(td, 'stderr')
            pidfile_path = os.path.join(td, 'pid')
            with open(config_path, 'w') as f:
                f.write(textwrap.dedent('''\
                start {target_ip}
                end {target_ip}
                interface {interface}
                max_leases 1
                lease_file {leases_path}
                pidfile {pidfile_path}
                boot_file pxelinux.0
                option dns {host_ip}
                option broadcast {broadcast_ip}
                ''').format(**locals()))
            with open(stdout_path, 'w') as stdout, \
                 open(stderr_path, 'w') as stderr:
                sp = subprocess.Popen(['udhcpd', '-f', config_path], cwd=td,
                                      stdin=open(os.devnull), stdout=stdout,
                                      stderr=stderr)
                try:
                    with executor(sp.pid):
                        yield
                finally:
                    sp.terminate()

    def get_interface_ip(self, interface):
        ip_addresses = []
        info = cliapp.runcmd(['ip', '-o', '-f', 'inet',
                              'addr', 'show', interface]).rstrip('\n')
        if info:
            tokens = collections.deque(info.split()[1:])
            ifname = tokens.popleft()
            while tokens:
                tok = tokens.popleft()
                if tok == 'inet':
                    address = tokens.popleft()
                    address, netmask = address.split('/')
                    ip_addresses.append(address)
                elif tok == 'brd':
                    tokens.popleft() # not interested in broadcast address
                elif tok == 'scope':
                    tokens.popleft() # not interested in scope tag
                else:
                    continue
        if not ip_addresses:
            raise cliapp.AppException('Interface %s has no addresses'
                                      % interface)
        if len(ip_addresses) > 1:
            warnings.warn('Interface %s has multiple addresses, '
                          'using first (%s)' % (interface, ip_addresses[0]))
        return ip_addresses[0]

    def ipmi_set_target_vlan(self):
        if any(env_var.startswith('IPMI_') for env_var in os.environ):
            # Needs IPMI_USER, IPMI_PASSWORD, IPMI_HOST and PXEBOOT_VLAN
            default = textwrap.dedent('''\
                ipmitool -I lanplus -U "$IPMI_USER" -E -H "$IPMI_HOST" \\
                    lan set 1 vlan id "$PXEBOOT_VLAN"
            ''')
        else:
            default = textwrap.dedent('''\
                while true; do
                    echo Please set the target\\'s vlan to $PXEBOOT_VLAN, \\
                         then enter \\"vlanned\\"
                    read
                    if [ "$REPLY" = vlanned ]; then
                        break
                    fi
                done
            ''')
        command = os.environ.get('PXEBOOT_SET_VLAN_COMMAND', default)
        subprocess.check_call(['sh', '-euc', command, '-'])

    def ipmi_pxe_reboot_target(self):
        if any(env_var.startswith('IPMI_') for env_var in os.environ):
            # Needs IPMI_USER, IPMI_PASSWORD, IPMI_HOST and PXEBOOT_VLAN
            default = textwrap.dedent('''\
                set -- ipmitool -I lanplus -U "$IPMI_USER" -E -H "$IPMI_HOST"
                "$@" chassis bootdev pxe
                "$@" chassis power reset
            ''')
        else:
            default = textwrap.dedent('''\
                while true; do
                    echo Please reboot the target in PXE mode, then\\
                         enter \\"pxe-booted\\"
                    read
                    if [ "$REPLY" = pxe-booted ]; then
                        break
                    fi
                done
            ''')
        command = os.environ.get('PXEBOOT_PXE_REBOOT_COMMAND', default)
        subprocess.check_call(['sh', '-euc', command, '-'])

    def wait_for_target_to_install(self):
        command = os.environ.get(
            'PXEBOOT_WAIT_INSTALL_COMMAND',
            textwrap.dedent('''\
                while true; do
                    echo Please wait for the system to install, then \\
                         enter \\"installed\\"
                    read
                    if [ "$REPLY" = installed ]; then
                        break
                    fi
                done
            '''))
        subprocess.check_call(['sh', '-euc', command, '-'])

    def ipmi_unset_target_vlan(self):
        if any(env_var.startswith('IPMI_') for env_var in os.environ):
            # Needs IPMI_USER, IPMI_PASSWORD, IPMI_HOST
            default = textwrap.dedent('''\
                ipmitool -I lanplus -U "$IPMI_USER" -E -H "$IPMI_HOST" \\
                    lan set 1 vlan id off
            ''')
        else:
            default = textwrap.dedent('''\
                while true; do
                    echo Please reset the target\\'s vlan, \\
                         then enter \\"unvlanned\\"
                    read
                    if [ "$REPLY" = unvlanned ]; then
                        break
                    fi
                done
            ''')
        command = os.environ.get('PXEBOOT_UNSET_VLAN_COMMAND', default)
        subprocess.check_call(['sh', '-euc', command, '-'])

    def ipmi_reboot_target(self):
        if any(env_var.startswith('IPMI_') for env_var in os.environ):
            # Needs IPMI_USER, IPMI_PASSWORD, IPMI_HOST
            default = textwrap.dedent('''\
                ipmitool -I lanplus -U "$IPMI_USER" -E -H "$IPMI_HOST" \\
                    chassis power reset
            ''')
        else:
            default = textwrap.dedent('''\
                while true; do
                    echo Please reboot the target, then\\
                         enter \\"rebooted\\"
                    read
                    if [ "$REPLY" = rebooted ]; then
                        break
                    fi
                done
            ''')
        command = os.environ.get('PXEBOOT_REBOOT_COMMAND', default)
        subprocess.check_call(['sh', '-euc', command, '-'])

    def process_args(self, (temp_root, macaddr)):
        interface = os.environ.get('PXEBOOT_DEPLOYER_INTERFACE', None)
        vlan = os.environ.get('PXEBOOT_VLAN')
        if vlan is not None: vlan = int(vlan)
        mode = os.environ.get('PXEBOOT_MODE')
        if mode is None:
            if interface:
                if vlan is not None:
                    mode = 'spawn-vlan'
                else:
                    if 'PXEBOOT_CONFIG_TFTP_ADDRESS' in os.environ:
                        mode = 'existing-dhcp'
                    else:
                        mode = 'spawn-novlan'
            else:
                mode = 'existing-server'
        assert mode in ('spawn-vlan', 'spawn-novlan', 'existing-dhcp',
                        'existing-server')
        if mode == 'spawn-vlan':
            with self.vlan(interface=interface, vlan=vlan) \
                     as (host_ip, target_ip, broadcast_ip), \
                 self.tftp_server(host_ip=host_ip, interface=interface) \
                     as (tftp_port, tftproot), \
                 self.local_pxelinux(tftproot=tftproot), \
                 self.local_kernel(rootfs=temp_root, tftproot=tftproot), \
                 self.local_nfsroot(rootfs=temp_root, target_ip=target_ip), \
                 self.local_pxeboot_config(tftproot=tftproot, macaddr=macaddr,
                                           ip=host_ip, tftp_port=tftp_port,
                                           nfsroot_dir=temp_root), \
                 self.dhcp_server(interface=interface, host_ip=host_ip,
                                  target_ip=target_ip,
                                  broadcast_ip=broadcast_ip):
                self.ipmi_set_target_vlan()
                self.ipmi_pxe_reboot_target()
                self.wait_for_target_to_install()
                self.ipmi_unset_target_vlan()
                self.ipmi_reboot_target()
        elif mode == 'spawn-novlan':
            with self.static_ip(interface=interface) as (host_ip, target_ip,
                            broadcast_ip), \
                 self.tftp_server(host_ip=host_ip, interface=interface,
                                  tftp_port=69) \
                     as (tftp_port, tftproot), \
                 self.local_pxelinux(tftproot=tftproot), \
                 self.local_kernel(rootfs=temp_root, tftproot=tftproot), \
                 self.local_nfsroot(rootfs=temp_root, target_ip=target_ip), \
                 self.local_pxeboot_config(tftproot=tftproot, macaddr=macaddr,
                                           ip=host_ip, tftp_port=tftp_port,
                                           nfsroot_dir=temp_root), \
                 self.dhcp_server(interface=interface, host_ip=host_ip,
                                  target_ip=target_ip,
                                  broadcast_ip=broadcast_ip):
                self.ipmi_pxe_reboot_target()
                self.wait_for_target_to_install()
                self.ipmi_reboot_target()
        elif mode == 'existing-dhcp':
            ip = self.get_interface_ip(interface)
            config_tftpaddr = os.environ['PXEBOOT_CONFIG_TFTP_ADDRESS']
            with self.tftp_server(ip=ip, interface=interface, tftp_port=69) \
                     as (tftp_port, tftproot), \
                 self.local_kernel(rootfs=temp_root, tftproot=tftproot), \
                 self.local_nfsroot(rootfs=temp_root, client_ip=''):
                kernel_tftproot = 'tftp://{}:{}/'.format(ip, tftp_port)
                rootfs_nfsroot = '{}:{}'.format(ip, temp_root)
                with self.remote_pxeboot_config(
                             tftproot=config_tftpaddr,
                             kernel_tftproot=kernel_tftproot,
                             kernel_subpath='kernel',
                             rootfs_nfsroot=nfsroot,
                             rootfs_subpath='',
                             macaddr=macaddr):
                    self.ipmi_pxe_reboot_target()
                    self.wait_for_target_to_install()
                    self.ipmi_reboot_target()
        elif mode == 'existing-server':
            config_tftpaddr = os.environ[    'PXEBOOT_CONFIG_TFTP_ADDRESS']
            kernel_tftpaddr = os.environ.get('PXEBOOT_KERNEL_TFTP_ADDRESS',
                                             config_tftpaddr)
            url = urlparse.urlsplit(kernel_tftpaddr)
            kernel_tftproot = os.environ.get('PXEBOOT_KERNEL_TFTP_ROOT',
                                             'tftp://%s/%s' % (url.hostname,
                                                               url.path))
            rootfs_rsync    = os.environ['PXEBOOT_ROOTFS_RSYNC_ADDRESS']
            url = urlparse.urlsplit(rootfs_rsync)
            nfsroot  = os.environ.get('PXEBOOT_ROOTFS_NFSROOT',
                                      '%s:%s' % (url.hostname, url.path))
            with self.remote_kernel(rootfs=temp_root, url=kernel_tftpaddr,
                                    macaddr=macaddr) as kernel_subpath, \
                 self.remote_nfsroot(rootfs=temp_root, rsync_url=rootfs_rsync)\
                     as rootfs_subpath, \
                 self.remote_pxeboot_config(tftproot=config_tftpaddr,
                                            kernel_tftproot=kernel_tftproot,
                                            kernel_subpath=kernel_subpath,
                                            rootfs_nfsroot=nfsroot,
                                            rootfs_subpath=rootfs_subpath,
                                            macaddr=macaddr):
                self.ipmi_pxe_reboot_target()
                self.wait_for_target_to_install()
                self.ipmi_reboot_target()
        else:
            cliapp.AppException('Invalid PXEBOOT_MODE: %s' % mode)

PXEBoot().run()