3:33 a.m.
Hi.
At playing libvirt-lxc on Fedora18, I found that the user needs
some workarounds to run /sbin/init as the root process of container.
With Fedora15, I found this https://gist.github.com/peo3/1142202.
And I know virt-sandbox-service have some clever way to understand RPM
to make domain running with a service.
Here is a script I wrote for F18 inspired by above two. Creating
LXC domain running systemd as /init program. I'd like to get
some feedback....and ...can't this kind of scripts be maintained by some
virt-tools project ?
Anyway, playing with lxc is fun. I'm glad if someone makes this script better :)
==
A user can create a lxc container by
# ./lxc_systemd_setup.py -r -n Test
This will generate my.xml and lxc file tree on /opt/lxc/Test
# virsh -c lxc:/// define my.xml
# virsh -c lxc:/// start my.xml
This domain has following characteristics
- /usr is bind mounted to host's /usr
- all files other than files in /usr are copied
- systemd and pam modules are tweaked a bit
- eth0 is up by dhcp.
- systemd, rsyslog, sshd is running.
Users can add rpm package as
# ./lxc_systemd_setup.py -r -n Test -a httpd
some options may not work because of my bad skills.
==lxc_systemd_setup.py==
#!/usr/bin/python
#
# A scripts for creating LXC domain where some daemons are running under systemd.
# Tested with Fedora18, running systemd, rsyslog, sshd in a container at default.
#
# Most config files, including all security settings as passwd, selinux,
# ssl/pki files are copied from the host. So, please fix them before
# running a domain.
#
# New root dir will be /opt/lxc/<domain name> at default and domain XML
# definition will be saved as my.xml
#
# All instllation under /usr is shared among containres/host, binaries are
# not copied at all. /etc and /var are copied. So, you can adjust config files
# under container as you like.
#
# for easy creation, run
# # lxc_systemd_setup.py -n Test -r
# # virsh -c lxc:/// define my.xml
# # virsh -c lxc:/// start Test --console
#
# This will build a lxc root filesystem under /opt/lxc/Test and copy
# required files under it. /usr will be shared with the host.
#
# to add some packages, pass package name with '-a' option. But this script
doesn't
# handle dependency of RPM, at all. please take care of it.
#
# for running httpd.
# # lxc_systemd_setup.py -n Test -r -a httpd
# _and_ you need to fix hostname lookup problem to run httpd. i.e. you may need to fix
# some files under /etc....
#
# please see
# # lxc_systemd_setup.py --help
# for other options. some may not work ;)
#
import sys, os, shutil
from subprocess import Popen, PIPE
from optparse import OptionParser,OptionGroup
import re
import rpm
parser = OptionParser()
parser.add_option('-p', '--prefix', action='store',
default='/opt/lxc',
type='string', dest='pathname', help='prefix of guest root
path')
parser.add_option('-n', '--name', action='store',
default='_unknown',
type='string', dest='domain_name', help='name of
domain')
parser.add_option('-o', '--out', action='store',
default='my.xml',
type='string', dest='def_file', help='name of generated
xml def')
parser.add_option('-r', '--renew', action='store_true',
default=False,
dest='renew_tree', help='delete existing tree if exists')
parser.add_option('-D', '--destroy', action='store_true',
default=False,
dest='destroy_tree', help='destroy existing tree and quit')
parser.add_option('-f', '--force', action='store_true',
default=False,
dest='force', help='update all files without checking
timestamp')
parser.add_option('-a','--add-packages', action='append',
type='string', dest='package_list', help='copy package
config to container')
parser.add_option('-s','--skip-packages', action='append',
type='string', dest='skip_list', help='skip
packages')
parser.add_option('-m','--memory', action='store',
default='1024000',
type='str', dest='memory', help='memory size of
domain')
parser.add_option('-H','--hostname', action='store',
default='lxc',
type='str', dest='hostname', help='hostname of
domain')
(options, args) = parser.parse_args(sys.argv)
#
# Utility functions.
#
#
# Remove all files under domain ROOT.
#
def destroy_all(path) :
if (not os.path.exists(path)) :
return
shutil.rmtree(path, ignore_errors=True)
#
# Check a file in a container is newer than hosts.
#
def file_is_newer(a, b) :
time_a = os.stat(a).st_mtime
time_b = os.stat(b).st_mtime
return a > b
#
# Check Host's distro.
#
def check_version() :
useRPM=True
version="unknown"
if (os.path.exists('/etc/redhat-release')) :
with open('/etc/redhat-release') as f:
version_string = f.readline()
if (re.match("Fedora release 18.+$", version_string)) :
version = "Fedora18"
else :
useRPM=False
return (version, useRPM)
#
# directories created at domain creation (tested with Fedora 18)
#
ROOTDIR= options.pathname + "/" + options.domain_name
class InstallInfo :
def __init__(self) :
self.DIRS = []
self.BINDDIRS = []
self.SYMLINKS=[]
self.PACKAGES = []
self.FILES = []
self.MERGED = []
def add_dirs(self, x) :
if (isinstance(x, str)) :
x = [x]
self.DIRS = self.DIRS + x
def dirs(self) :
return self.DIRS
def add_files(self, x) :
if (isinstance(x, str)) :
x = [x]
self.FILES += x
def files(self) :
return self.FILES
def add_binds(self, x) :
if (isinstance(x, str)) :
x = [x]
self.BINDDIRS = self.BINDDIRS + x
def binds(self) :
return self.BINDDIRS
def add_links(self, x) :
self.SYMLINKS = self.SYMLINKS + x
def links(self) :
return self.SYMLINKS
def add_packages(self, x) :
self.PACKAGES = self.PACKAGES + x
def packages(self) :
return self.PACKAGES
def merge(self) :
self.DIRS = list(set(self.DIRS))
self.FILES = list(set(self.FILES))
self.BINDDIRS = sorted(list(set(self.BINDDIRS)))
ret = True
ents =[]
paths = []
for ent in self.DIRS :
ents.append((ent, 'dir', ''))
paths.append(ent)
for ent in self.FILES :
ents.append((ent, 'file', ''))
paths.append(ent)
for ent in self.SYMLINKS :
ents.append((ent[0], 'link', ent[1]))
paths.append(ent[0])
if (len(paths) - len(list(set(paths)))) :
ret = False
self.MERGED = sorted(ents)
return ret
def merged(self) :
return self.MERGED
#
# Gather RPM information and copy config files to proper place.
#
class CopyRPMHandler:
def __init__(self, name) :
self.name = name
self.files = []
self.service = ""
def verify(self) :
ts = rpm.TransactionSet()
mi = ts.dbMatch('name', self.name)
if not mi :
return False
# get list of files.
for h in mi :
myhead = h
break
fi = myhead.fiFromHeader()
for x in fi :
self.files.append(x[0]);
self.test_service()
self.strip_binds()
return True
def paths(self) :
return self.files
#
# check all files in RPM which are not under bind-mount.
#
def strip_binds(self) :
# remove all ents under /usr for avoiding copy.
temp = self.files
self.files = []
for file in temp :
if (file == '') :
continue
if (re.match("/usr/.+$", file)) :
continue
if (re.match("/bin/.+$", file)) :
continue
if (re.match("/lib/.+$", file)) :
continue
if (re.match("/sbin/.+$", file)) :
continue
if (re.match("/lib64/.+$", file)) :
continue
self.files.append(file)
self.files.sort()
return
def test_service(self) :
for file in self.files :
if (re.match("/usr/lib/systemd/system.+\.service$", file)) :
ent.service = file
#
# Functions for workarounds.
#
#
# systemd: create our own basic.target for avoiding some startups.
#
def systemd_tune() :
#
# we need to avoid some special services by systemd.
# modify basic.target and avoid them.
#
filename = ROOTDIR + "/etc/systemd/system/basic.target"
data="""[Unit]
Description=Basic System
Documentation=man:systemd.special(7)
Requires=systemd-tmpfiles-setup.service sockets.target
After=systemd-tmpfiles-setup.service sockets.target
RefuseManualStart=yes
"""
with open(filename,"w") as f:
f.write(data)
#
# we need getty only with tty1
#
os.symlink("/usr/lib/systemd/system/getty@.service",
ROOTDIR + "/etc/systemd/system/getty.target.wants/getty(a)tty1.service")
#
# Create ifcfg-eth0 and add service to bring up it.
#
def eth0_service() :
#
# /etc/sysconfig/network is generated by annaconda and we cannot
# find it by rpms.
#
filename = ROOTDIR + "/etc/sysconfig/network"
shutil.copy("/etc/sysconfig/network", filename);
#
# ifconfig setting for eth0
#
filename = ROOTDIR + "/etc/sysconfig/network-scripts/ifcfg-eth0"
data="""DEVICE=eth0
BOOTPROTO=dhcp
ONBOOT=yes
NAME=eth0
TYPE=Ethernet
"""
with open(filename, "w") as f:
f.write(data)
print "Creating %s" % filename
filename = ROOTDIR + "/etc/systemd/system/lxc-eth0.service"
data="""[Unit]
Before=multi-user.target
Conflicts=shutdown.target
Description=bring up eth0 in this container
[Service]
ExecStart=/usr/sbin/ifup eth0
Type=simple
"""
with open(filename, "w") as f:
f.write(data)
print "Creating %s" % filename
#
# Bring up this.
#
filename = ROOTDIR +
"/etc/systemd/system/basic.target.wants/lxc-eth0.service"
src = "/etc/systemd/system/lxc-eth0.service"
os.symlink(src, filename)
#
# Make fstab empty
#
def empty_fstab() :
filename = ROOTDIR + "/etc/fstab"
with open(filename, "w") as f:
f.truncate(0)
#
# in Fedora18, pam's pam_loginuid.so doesn't work under container
# we need to disable it.
#
def pam_tune() :
pamdir = ROOTDIR + "/etc/pam.d"
for root, dirs, files in os.walk(pamdir) :
for path in files :
path = root + "/" + path
if (os.path.islink(path)) :
continue
data =""
with open(path) as f:
for line in f :
if (re.match("^.+pam_loginuid.so.*$", line)) :
line = "#" + line
data += line
with open(path, "w") as f:
f.write(data)
#
# securetty set up for login via system console.
#
def securetty_tune() :
path = ROOTDIR + "/etc/securetty"
with open(path, "a") as f:
f.write("pts/0\n")
#
# set hostname of guest domain.
#
def hostname_modify() :
path = ROOTDIR + "/etc/hostname"
with open(path, "w") as f:
f.write(options.hostname + "\n")
#
# parse memory size.
#
def parse_memory(data) :
if data[-1] == 'K' :
x = int(data[0:-1])
return str(x * 1024)
elif data[-1] == 'M' :
x = int(data[0:-1])
return str(x * 1024 * 1024)
elif data[-1] == 'G' :
x = int(data[0:-1])
return str(x * 1024 * 1024 * 1024)
else :
return data
#
# Main routine starts here !
#
version, useRPM = check_version()
if (not useRPM) :
print 'now, we can handle RPM only'
exit(1)
info = InstallInfo()
# Build a information.
#
# At first, gather required RPM information and some tweaks for distro.
#
if (version == 'Fedora18') :
#
# now, dont'handle yum and rpm info in container, so create fake dirs
# instead of copying yum info by RPM.
#
info.add_dirs(["/etc/yum", "/etc/yum/protected.d",
"/etc/yum/pluginconf.d","/etc/yum/vars"])
#
# We share /usr between host and guest.
#
info.add_binds(["/usr"])
#
# For Fedora18, we need following copies of configs packages at least.
#
info.add_packages(["filesystem","setup","rpm",
"selinux-policy"])
info.add_packages(["systemd", "dbus",
"initscripts","util-linux"])
info.add_packages(["pam","passwd",
"crontabs","kmod","logrotate","rsyslog"])
info.add_packages(["openssh","openssh-server",
"chkconfig","authconfig"])
info.add_packages(["glibc", "mailcap"])
# symlink and dirs for systemd
info.add_links([["/etc/systemd/system/default.target",
"/lib/systemd/system/multi-user.target"]])
info.add_dirs(["/etc/systemd/system/basic.target.wants"])
info.add_dirs(["/etc/systemd/system/default.target.wants"])
info.add_dirs(["/etc/systemd/system/getty.target.wants"])
info.add_dirs(["/etc/systemd/system/multi-user.target.wants"])
info.add_dirs(["/etc/systemd/system/sockets.target.wants"])
info.add_dirs(["/etc/systemd/system/sysinit.target.wants"])
info.add_dirs(["/etc/systemd/system/system-update.target.wants"])
#
# Merge package list
#
package_names = info.packages()
if (options.package_list) :
package_names += options.package_list
# Uniq.
package_names = list(set(package_names))
#
# delete unnecessary packages from list.
#
if (options.skip_list) :
for name in options.skip_list :
if (name in package_names) :
package_names.remove(name)
#
# Verify package list (check installation of packages)
#
packages = []
error = False
if (useRPM) :
for name in package_names :
ent = CopyRPMHandler(name)
if (ent.verify()) :
packages.append(ent)
else :
print "Couldn't find a package [%s] in RPM DB." % (name)
error = True
if (error) :
exit(1)
#
# Now, we confirmed all RPMS required are installed in the host.
#
service_files = []
#
# Extract dir,symlink,file information from RPMS. Later, we'll copy all
# files other than /usr.
#
for ent in packages :
for path in ent.paths() :
if (not os.path.exists(path)) :
continue
if (os.path.islink(path)) :
src = os.readlink(path)
info.add_links([[path, src]])
elif (os.path.isfile(path)) :
info.add_files(path)
elif (os.path.isdir(path)) :
info.add_dirs(path)
if (ent.service != ""):
service_files.append(ent.service)
#
# Uniq and sort it.
#
if (not info.merge()) :
print "some confilction of files may happen..."
#
# Check Domain name is passed.
#
if (options.domain_name == '_unknown') :
print "Guest Domain name must be specified"
exit(1)
#
# Destroy tree.
#
if (options.destroy_tree) :
destroy_all(ROOTDIR)
exit(0)
#
# At first, clear tree if required.
# (*) the scirpt may not work if we don't destroy the tree ....
#
if (os.path.exists(ROOTDIR)) :
if (options.renew_tree) :
destroy_all(ROOTDIR)
# Create root dir
try:
os.mkdir(ROOTDIR)
except:
print "cannot create root dir %s" % ROOTDIR
exit(1)
# Ok, make world based on information gathered from RPMS.
for ents in info.merged() :
guestpath = ROOTDIR + ents[0]
try:
if (ents[1] == 'dir') :
if (not os.path.exists(guestpath)) :
print "Creating dir %s" % (guestpath)
os.makedirs(guestpath)
elif (ents[1] == 'link') :
if (not os.path.exists(guestpath)) :
print "Creating symlink %s => %s" % (guestpath, ents[2])
os.symlink(ents[2], guestpath)
elif (ents[1] == 'file') :
if (options.force or
not os.path.exists(guestpath) or
file_is_newer(ents[0], guestpath)) :
print "Copyfile %s" % (guestpath)
shutil.copy(ents[0], guestpath)
except:
print "error at creating tree %s" % guestpath
exit(1)
#
# setup service files if necessary.
#
for file in service_files :
service = os.path.basename(file)
p = re.compile('WantedBy=(.+)$')
for line in open(file, 'r') :
m = p.match(line)
if (m) :
target = m.group(1)
pathname = ROOTDIR + "/etc/systemd/system/" + target +
".wants/" + service
print "%s=>%s" % (pathname, file)
os.symlink(file, pathname)
#
# Tweak system settings.
#
if (version == "Fedora18") :
# diable some services.
dir = ROOTDIR + "/etc/systemd/system/"
os.symlink("/dev/null", dir + "sysinit.target")
os.symlink("/dev/null", dir + "console-shell.service")
os.symlink("/dev/null", dir + "fedora-readonly.service")
os.symlink("/dev/null", dir + "fedora-storage-init.service")
systemd_tune() # modify basic.target etc...
eth0_service() # bringup eth0 without udev
empty_fstab() # make /etc/fstab empty
pam_tune() # disable some pam module
securetty_tune() # add pts/0 to securetty
hostname_modify()
#
# Generate a Domain Def.
#
domain = r"""
<domain type='lxc'>
<name>%(NAME)s</name>
<memory unit='bytes'>%(MEMORY)s</memory>
<vcpu>1</vcpu>
<os>
<type arch='x86_64'>exe</type>
<init>/sbin/init</init>
</os>
<clock offset='utc'/>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>destroy</on_crash>
<devices>
<emulator>/usr/libexec/libvirt_lxc</emulator>
<filesystem type='mount' accessmode='passthrough'>
<source dir='%(ROOTDIR)s'/>
<target dir='/'/>
</filesystem>
<filesystem type='mount' accessmode='passthrough'>
<source dir='/usr'/>
<target dir='/usr'/>
</filesystem>
<filesystem type='ram'>
<source usage='%(MEMORY)s'/>
<target dir='/tmp'/>
</filesystem>
<filesystem type='ram'>
<source usage='%(MEMORY)s'/>
<target dir='/dev/shm'/>
</filesystem>
<interface type="network">
<source network="default"/>
</interface>
<console type='pty'>
<target type='lxc' port='0'/>
</console>
</devices>
</domain>
""" % {'NAME':options.domain_name,
'MEMORY': parse_memory(options.memory),
'ROOTDIR':ROOTDIR}
with open(options.def_file, "w") as f :
f.write(domain)