path: root/koan/xencreate.py

#!/usr/bin/python
#
# Xen creation functions.  Code originated from xenguest-install.
#
# Copyright 2005-2006  Red Hat, Inc.
# Jeremy Katz <katzj@redhat.com>
# Option handling added by Andrew Puch <apuch@redhat.com>
# Simplified for use as library by koan, Michael DeHaan <mdehaan@redhat.com>
#
# This software may be freely redistributed under the terms of the GNU
# general public license.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

import os, sys, time, stat
import tempfile
import random
from optparse import OptionParser
import exceptions
import errno

XENCONFIGPATH="/etc/xen/"
XENDOMAINPATH="/etc/xen/domains/"

PYTEMPLATE = """
# Automatically generated xen config file
name = "%(name)s"
memory = "%(ram)s"
disk = [ '%(disktype)s:%(disk)s,xvda,w' ]
vif = [ 'mac=%(mac)s' ]
uuid = "%(uuid)s"
bootloader="/usr/bin/pygrub"
on_reboot   = 'destroy'
on_crash    = 'destroy'
"""

XMLTEMPLATE = """
<domain type='xen'>
  <name>%(name)s</name>
  <os>
    <type>linux</type>
    <kernel>%(kernel)s</kernel>
    <initrd>%(initrd)s</initrd>
    <root>/dev/xvd</root>
    <cmdline>ro %(extra)s</cmdline>
  </os>
  <memory>%(ramkb)s</memory>
  <vcpu>1</vcpu>
  <uuid>%(uuid)s</uuid>
  <on_reboot>restart</on_reboot>
  <on_poweroff>destroy</on_poweroff>
  <on_crash>destroy</on_crash>
  <devices>
    <disk type='file'>
      <source file='%(disk)s'/>
      <target dev='xvda'/>
    </disk>
    <interface type='bridge'>
      <source bridge='xenbr0'/>
      <mac address='%(mac)s'/>
      <script path='/etc/xen/scripts/vif-bridge'/>
    </interface>
  </devices>
</domain>
"""

class XenCreateException(exceptions.Exception):
    pass

def randomMAC():
    """
    from xend/server/netif.py
    Generate a random MAC address.
    Uses OUI 00-16-3E, allocated to
    Xensource, Inc.  Last 3 fields are random.
    return: MAC address string
    """
    mac = [ 0x00, 0x16, 0x3e,
            random.randint(0x00, 0x7f),
            random.randint(0x00, 0xff),
            random.randint(0x00, 0xff) ]
    return ':'.join(map(lambda x: "%02x" % x, mac))

def randomUUID():
    """
    Generate a random UUID.  Copied from xend/uuid.py
    """
    return [ random.randint(0, 255) for _ in range(0, 16) ]

def uuidToString(u):
    """
    return uuid as a string
    """
    return "-".join(["%02x" * 4, "%02x" * 2, "%02x" * 2, "%02x" * 2,
                     "%02x" * 6]) % tuple(u)

def get_disk(disk,size):
    """
    Create a disk image if path does not exist.
    """
    if not os.path.exists(disk):
        fd = os.open(disk, os.O_WRONLY | os.O_CREAT)
        off = long(size * 1024L * 1024L * 1024L)
        os.lseek(fd, off, 0)
        os.write(fd, '\x00')
        os.close(fd)
    return disk

def get_uuid(uuid):
    """
    return the passed-in uuid, or a random one if it's not set.
    """
    if uuid:
       return uuid
    return uuidToString(randomUUID())

def get_mac(mac):
    """
    return the passed-in MAC, or a random one if it's not set.
    """
    if mac:
       return mac
    return randomMAC()

def get_paravirt_install_image(kernel_fn,initrd_fn):
    """
    Return a tuple of (kernel_filename, initrd_filename)
    where the filenames are copies of the kernel and initrd.
    This must be done because Xen deletes the kernel/initrd pairs
    that are originally passed in.
    """
    try:
        kernel = open(kernel_fn,"r")
        initrd = open(initrd_fn,"r")
    except IOError:
        raise XenCreateException("Invalid kernel or initrd location")

    (kfd, kfn) = tempfile.mkstemp(prefix="vmlinuz.", dir="/var/lib/xen")
    os.write(kfd, kernel.read())
    os.close(kfd)
    kernel.close()

    (ifd, ifn) = tempfile.mkstemp(prefix="initrd.img.", dir="/var/lib/xen")
    os.write(ifd, initrd.read())
    os.close(ifd)
    initrd.close()

    return (kfn, ifn)

def writeConfigPy(cfgdict):
    fd = open("%s%s" %(XENCONFIGPATH, cfgdict['name']), "w+")
    fd.write(PYTEMPLATE % cfgdict)
    fd.close()

def writeConfigXml(cfgdict):
    try:
        os.makedirs(XENDOMAINPATH)
    except OSError, (err, msg):
        if err != errno.EEXIST:
            raise OSError(err,msg)
    fd = open("%s%s.xml" % (XENDOMAINPATH,cfgdict['name']), "w+")
    fd.write(XMLTEMPLATE % cfgdict)
    fd.close()

def start_paravirt_install(name=None, ram=None, disk=None, mac=None,
                           uuid=None, kernel=None, initrd=None, extra=None):
    # this app works without libvirt (for auto-kickstart functionality)
    # but using xen functions will require it...
    import libvirt

    (kfn, ifn) = get_paravirt_install_image(kernel, initrd)
    if stat.S_ISBLK(os.stat(disk)[stat.ST_MODE]):
        ftype = "phy"
    else:
        ftype = "file"

    cfgdict = {
       'name'  : name,            'ram'      : ram,
       'ramkb' : int(ram) * 1024, 'disk'     : disk,
       'mac'   : mac,             'disktype' : ftype,
       'uuid'  : uuid,            'kernel'   : kfn,
       'initrd': ifn,             'extra'    : extra
    }
    cfgxml = XMLTEMPLATE % cfgdict

    try:
        conn = libvirt.open(None)
    except:
        raise XenCreateException("libvirt could not connect to Xen")
    if conn == None:
        raise XenCreateException("Unable to connect to hypervisor")
    dom = conn.createLinux(cfgxml, 0)
    if dom == None:
        raise XenCreateException("Unable to create domain for guest")

    cmd = ["/usr/sbin/xm", "console", "%s" %(dom.ID(),)]
    child = os.fork()
    if (not child):
        os.execvp(cmd[0], cmd)
        os._exit(1)
    time.sleep(5)
    os.unlink(kfn)
    os.unlink(ifn)

    # FIXME: if the domain doesn't exist now, it almost certainly crashed.
    # it'd be nice to know that for certain...
    try:
        conn.lookupByID(dom.ID())
    except libvirt.libvirtError:
        raise XenCreateException("It appears the installation has crashed")

    writeConfigPy(cfgdict)
    writeConfigXml(cfgdict)

    try:
        (pid, status) = os.waitpid(child, 0)
    except OSError, (errno, msg):
        raise XenCreateException("%s waitpid: %s" % (__name__,msg))

    # ensure there's time for the domain to finish destroying if the
    # install has finished or the guest crashed
    time.sleep(1)
    try:
        conn.lookupByID(dom.ID())
    except libvirt.libvirtError:
        return "Reconnect with /usr/sbin/xm create -c %s" % (name)
    else:
        return "Reconnect with /usr/sbin/xm console %s" % (name)