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#!/usr/bin/env python
#
# Example script for creating and building a new Linux guest OS for Xen.
# It takes an optional parameter that specifies offsets to be added to the
# ip address and root partition numbers, enabling multiple domains to be
# started from the one script.
#
# Edit as required...
#
import Xc, XenoUtil, string, sys, os, time, socket
# initialize a few variables that might come in handy
thishostname = socket.gethostname()
guestid = 0
if sys.argv >= 2:
guestid = string.atoi(sys.argv[1])
print "Offset to add to guest's IP etc : %d\n" % guestid
##### This section of the code establishes various settings to be used
##### for this guest virtual machine
# STEP 1. Specify kernel image file. Can be gzip'ed.
image = "../../../install/boot/xenolinux.gz"
# STEP 2. How many megabytes of memory for the new domain?
memory_megabytes = 64
# STEP 3. A handy name for your new domain.
domain_name = "This is VM %d" % guestid
# STEP 4. Specify IP address(es), netmask and gateway for the new
# domain. You need to configure IP addrs within the domain just as
# you do normally. This is just to let Xen know about them so it can
# route packets appropriately.
#ipaddr = ["111.222.333.444","222.333.444.555"]
ipaddr = [XenoUtil.add_offset_to_ip(XenoUtil.get_current_ipaddr(),guestid)]
netmask = XenoUtil.get_current_ipmask()
gateway = XenoUtil.get_current_ipgw()
nfsserv = '169.254.1.0' # You need to set this if you're using NFS root
# STEP 5. Identify any physcial partitions or virtual disks you want the
# domain to have access to, and what you want them accessible as
# e.g. vbds = [ ('phy:sda1','sda1', 'w'),
# ('phy:sda4','sda%d' % (3+guestid), 'r'),
# ('vd:as73gd784dh','hda1','w') ]
vbds = [ ('phy:sda%d'%(7+guestid),'sda1','w' ),
('phy:sda6','sda6','r'),
('phy:cdrom','hdd','r') ]
# STEP 6. Build the command line for the new domain. Edit as req'd.
# You only need the ip= line if you're NFS booting or the root file system
# doesn't set it later e.g. in ifcfg-eth0 or via DHCP
# You can use 'extrabit' to set the runlevel and custom environment
# variables used by custom rc scripts (e.g. DOMID=, usr= )
ipbit = "ip="+ipaddr[0]+":"+nfsserv+":"+gateway+":"+netmask+"::eth0:off"
rootbit = "root=/dev/sda1 ro"
#rootbit = "root=/dev/nfs nfsroot=/full/path/to/root/directory"
extrabit = "4 DOMID=%d usr=/dev/sda6" % guestid
cmdline = ipbit +" "+ rootbit +" "+ extrabit
# STEP 7. Set according to whether you want the script to watch the domain
# and auto-restart it should it die or exit.
auto_restart = False
#auto_restart = True
##### Print some debug info just incase things don't work out...
#####
print "Domain image : ", image
print "Domain memory : ", memory_megabytes
print "Domain IP address(es) : ", ipaddr
print "Domain block devices : ", vbds
print 'Domain cmdline : "%s"' % cmdline
##### Code beyond this point is actually used to manage the mechanics of
##### starting (and watching if necessary) guest virtual machines.
# Obtain an instance of the Xen control interface
xc = Xc.new()
# This function creates, builds and starts a domain, using the values
# in the global variables, set above. It is used in the subsequent
# code for starting the new domain and rebooting it if appropriate.
def make_domain():
"""Create, build and start a domain.
Returns: [int] the ID of the new domain.
"""
# set up access to the global variables declared above
global image, memory_megabytes, domain_name, ipaddr, netmask
global vbds, cmdline, xc
if not os.path.isfile( image ):
print "Image file '" + image + "' does not exist"
sys.exit()
id = xc.domain_create( mem_kb=memory_megabytes*1024, name=domain_name )
print "Created new domain with id = " + str(id)
if id <= 0:
print "Error creating domain"
sys.exit()
ret = xc.linux_build( dom=id, image=image, cmdline=cmdline )
if ret < 0:
print "Error building Linux guest OS: "
print "Return code from linux_build = " + str(ret)
xc.domain_destroy ( dom=id )
sys.exit()
# setup the virtual block devices
for ( uname, virt_name, rw ) in vbds:
virt_dev = XenoUtil.blkdev_name_to_number( virt_name )
segments = XenoUtil.lookup_disk_uname( uname )
if not segments:
print "Error looking up %s\n" % uname
xc.domain_destroy ( dom=id )
sys.exit()
if xc.vbd_create( dom=id, vbd=virt_dev, writeable= rw=='w' ):
print "Error creating VBD vbd=%d writeable=%d\n" % (virt_dev,rw)
xc.domain_destroy ( dom=id )
sys.exit()
for (s_dev,s_start,s_len,s_type) in segments:
if xc.vbd_grow( dom=id,
vbd=virt_dev,
device=s_dev,
start_sector=s_start,
nr_sectors=s_len ):
print "Error populating VBD vbd=%d\n" % virt_dev
xc.domain_destroy ( dom=id )
sys.exit()
# setup virtual firewall rules for all aliases
for ip in ipaddr:
XenoUtil.setup_vfr_rules_for_vif( id, 0, ip )
if xc.domain_start( dom=id ) < 0:
print "Error starting domain"
xc.domain_destroy ( dom=id )
sys.exit()
return id
# end of make_domain()
# The starting / monitoring of the domain actually happens here...
# start the domain and record its ID number
current_id = make_domain()
# if the auto_restart flag is set then keep polling to see if the domain is
# alive - restart if it is not by calling make_domain() again (it's necessary
# to update the id variable, since the new domain may have a new ID)
while auto_restart:
time.sleep(1)
if not xc.domain_getinfo(current_id):
print "The virtual machine has terminated, restarting in a new domain"
current_id = make_domain()
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