Difference between revisions of "Arch VServer"

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[[Category:Emulators (English)]][[Category: HOWTOs (English)]]
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[[Category:Virtualization]]
{{ stub }}
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This article aims to provide all necessary information regarding the creation of a vserver host as well as vserver guests running Arch Linux. This will enable you to setup virtual servers that provide different services as if they were on different machines, with a very little overhead. You can get more information about virtual servers [http://en.wikipedia.org/wiki/Virtual_private_server here].
{{ translateme }}
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=Introduction=
+
 
+
This article aims to provide all necessary information regarding the creation of a vserver host as well as vserver guests running ArchLinux. Tis will enable you to setup virtual servers that provide different services as if they were on different machines, with a very little overhead. You can get more information about virtual servers [http://en.wikipedia.org/wiki/Virtual_private_server here].
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+
====Current status / Next steps====
+
I've just started playing around with vserver and am finding the documentation regarding this project lacking. As such, the way I'm doing this below may not be optimal.
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That being said, I'm thinking that the next step to make this more efficient would be to write the proper scripts to integrate pacman into util-vserver as has been done for apt, rpm, etc... The actual files may be found in ''/usr/lib/util-vserver''.
+
  
 
=Preparing the Host=
 
=Preparing the Host=
  
To prepare the vserver host environment, you will need to install both a vserver patched kernel and the vserver utilities which are located in [http://wiki.archlinux.org/index.php/AUR AUR]. In the following steps, the instructions are provided using [http://wiki.archlinux.org/index.php/Yaourt yaourt] to fetch them automatically. This has the aded benefit of pulling down the required dependencies ( ''dietlibc'' and ''beecrypt'' ) automagically :
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To prepare the vserver host environment, you will need to install both a vserver patched kernel, the vserver utilities and their dependencies which are located in the [[AUR]]. The required packages are {{AUR|dietlibc}}, {{AUR|beecrypt}}, {{AUR|kernel26-vserver}} (not found or {{AUR|linux-vserver}} orphan), and {{AUR|util-vserver}}
 
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# yaourt -S kernel26-vserver util-vserver
+
  
 
=Paths of Interest=
 
=Paths of Interest=
Line 33: Line 21:
 
==Preparing the guest installation media==
 
==Preparing the guest installation media==
  
'''NOTE''' : This is all heavily inspired from [http://wiki.archlinux.org/index.php/Install_From_Existing_Linux wiki:Install From Existing Linux] and will therefore be quite brief when not mentioning Vserver specific steps.
+
'''NOTE''' : This is all heavily inspired from [[Install From Existing Linux]] and will therefore be quite brief when not mentioning Vserver specific steps.
  
 
===Optional: Base variables to follow along with the steps===
 
===Optional: Base variables to follow along with the steps===
Line 45: Line 33:
  
 
===Optional: Preparing the guest disk===
 
===Optional: Preparing the guest disk===
# Create a LVM Physical Volume, a Volume Group and a Logical Volume ( [http://wiki.archlinux.org/index.php/Lvm#Create_Logical_Volumes wiki:LVM] )
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# Create a LVM Physical Volume, a Volume Group and a Logical Volume ( [https://wiki.archlinux.org/index.php/Lvm#Create_Logical_Volumes wiki:LVM] )
 
# Create a filesystem on the lvm volume
 
# Create a filesystem on the lvm volume
 
# mkdir $GuestRoot
 
# mkdir $GuestRoot
Line 66: Line 54:
  
 
===Install the base system===
 
===Install the base system===
'''NOTE : ''' To save some time, it's probably a good idea to create a text file containing all the packages to install and call it via "pacman -Sy `cat $GuestPackages` -r $GuestRoot" instead of the following :  
+
'''NOTE : ''' To save some time, it's probably a good idea to create a text file containing all the packages to install and call it via "pacman -S `cat $GuestPackages` -r $GuestRoot" instead of the following :  
# pacman -Sy base -r $GuestRoot
+
# pacman -S base -r $GuestRoot
 
# Optional: If you want to chroot into the newly created guest so as to install new packages, it might be a good idea to mount a few filesystems required by some packages.
 
# Optional: If you want to chroot into the newly created guest so as to install new packages, it might be a good idea to mount a few filesystems required by some packages.
 
## Bind /dev, /proc, /sys to the corresponding directories in $GuestRoot
 
## Bind /dev, /proc, /sys to the corresponding directories in $GuestRoot
 
# Modify guest configuration files to enable a smoother boot process
 
# Modify guest configuration files to enable a smoother boot process
## Modify '''/etc/inittab''' by deleting all lines that create the consoles ( agetty )
+
## Modify '''/etc/rc.shutdown''' by removing anything hardware/clock/mount related. This includes most everything under ''Saving Random Seed'.
## Modify '''/etc/rc.shutdown''' by removing anything hardware/clock/mount related. This  
+
includes most everything under ''Saving Random Seed'.
+
 
## Modify '''/etc/rc.sysinit''' by anything hardware/clock/mount related.
 
## Modify '''/etc/rc.sysinit''' by anything hardware/clock/mount related.
## Create '''/etc/init.d/rc'''
 
 
## Modify '''/etc/syslog-ng.conf''' by removing file("/proc/kmsg")
 
## Modify '''/etc/syslog-ng.conf''' by removing file("/proc/kmsg")
## Modify '''/etc/rc.conf''' by removing the networks Daemon.
 
 
===Annexe : Configuration files modified===
 
'''/etc/init.d/rc'''
 
if [ $1 -eq 3 ]; then
 
echo "entering runlevel 3:multi";
 
/etc/rc.multi
 
fi
 
if [ $1 -eq 6 ]; then
 
echo "entering runlevel 6:reboot";
 
/etc/rc.shutdown
 
fi
 
if [ $1 -eq 0 ]; then
 
echo "entering runlevel 0: shutdown";
 
/etc/rc.shutdown
 
fi
 
if [ $1 -eq 4 ]; then
 
echo "entering runlevel 4";
 
fi
 
if [ $1 -eq 5 ]; then
 
echo "entering runlevel 5";
 
fi
 
if [ $1 -eq 1 ]; then
 
echo "entering runlevel 1:single";
 
/etc/rc.single
 
fi
 
if [ $1 -eq 2 ]; then
 
echo "entering runlevel 2:multi";
 
/etc/rc.multi
 
fi
 
 
====/etc/rc.sysinit====
 
#!/bin/bash
 
#
 
# /etc/rc.sysinit
 
#
 
 
. /etc/rc.conf
 
. /etc/rc.d/functions
 
 
echo " "
 
printhl "Arch Linux\n"
 
printhl "${C_H2}http://www.archlinux.org"
 
printhl "Copyright 2002-2007 Judd Vinet"
 
printhl "Copyright 2007-2009 Aaron Griffin"
 
printhl "Distributed under the GNU General Public License (GPL)"
 
printsep
 
 
 
# start up our mini logger until syslog takes over
 
/sbin/minilogd
 
 
if [ -x /sbin/udevadm ]; then
 
stat_busy "Starting UDev Daemon"
 
/sbin/udevd --daemon
 
stat_done
 
else
 
# Static /dev, our last resort
 
status "Using static /dev filesystem" true
 
fi
 
 
# Trigger udev uevents
 
if /bin/pidof -o %PPID /sbin/udevd >/dev/null; then
 
  stat_busy "Triggering UDev uevents"
 
  /sbin/udevadm trigger
 
  stat_done
 
fi
 
  NETFS="nonfs,nonfs4,nosmbfs,nocifs,nocodafs,noncpfs,nosysfs,noshfs,nofuse,nofuseblk,noglusterfs"
 
 
stat_busy "Mounting Local Filesystems"
 
/bin/rm -f /etc/mtab*
 
# Write /proc, /sys and /dev to /etc/mtab
 
if [ -e /proc/mounts ]; then
 
/bin/grep -e "rootfs" -e "/proc " -e "/sys " -e "/dev " /proc/mounts >>    /etc/mtab
 
fi
 
stat_done
 
 
 
stat_busy "Configuring System Clock"
 
if [ ! -f /var/lib/hwclock/adjtime ]; then
 
echo "0.0 0 0.0" > /var/lib/hwclock/adjtime
 
fi
 
if [ "$TIMEZONE" != "" -a -e "/usr/share/zoneinfo/$TIMEZONE" ]; then
 
/bin/rm -f /etc/localtime
 
/bin/cp "/usr/share/zoneinfo/$TIMEZONE" /etc/localtime
 
fi
 
 
if [ -n "$HWCLOCK_PARAMS" ]; then
 
/sbin/hwclock --adjust #Adjust for system drift
 
/sbin/hwclock $HWCLOCK_PARAMS
 
fi
 
stat_done
 
 
RANDOM_SEED=/var/lib/misc/random-seed
 
if [ -f $RANDOM_SEED ]; then
 
stat_busy "Initializing Random Seed"
 
/bin/cat $RANDOM_SEED > /dev/urandom
 
stat_done
 
fi
 
 
stat_busy "Removing Leftover Files"
 
/bin/rm -f /etc/nologin &>/dev/null
 
/bin/rm -f /etc/shutdownpid &>/dev/null
 
/bin/rm -f /var/lock/* &>/dev/null
 
/bin/rm -rf /tmp/* /tmp/.* &>/dev/null
 
/bin/rm -f /forcefsck &>/dev/null
 
(cd /var/run && /usr/bin/find . ! -type d -exec /bin/rm -f -- {} \; )
 
: > /var/run/utmp
 
/bin/chmod 0664 /var/run/utmp
 
# Keep {x,k,g}dm happy with xorg
 
/bin/mkdir /tmp/.ICE-unix && /bin/chmod 1777 /tmp/.ICE-unix
 
/bin/mkdir /tmp/.X11-unix && /bin/chmod 1777 /tmp/.X11-unix
 
stat_done
 
 
#status "Updating Shared Library Links" /sbin/ldconfig
 
 
if [ "$HOSTNAME" != "" ]; then
 
status "Setting Hostname: $HOSTNAME" /bin/hostname $HOSTNAME
 
fi
 
 
# Set the NIS domain name, if necessary
 
[ -f /etc/conf.d/nisdomainname ] && . /etc/conf.d/nisdomainname
 
if [ "$NISDOMAINNAME" != "" ]; then
 
status "Setting NIS Domain Name: $NISDOMAINNAME" /bin/nisdomainname  $NISDOMAINNAME
 
fi
 
 
status "Updating Module Dependencies" /sbin/depmod -A
 
 
# Flush old locale settings
 
: >/etc/profile.d/locale.sh
 
/bin/chmod 755 /etc/profile.d/locale.sh
 
# Set user defined locale
 
[ -z "$LOCALE" ] && LOCALE="en_US"
 
stat_busy "Setting Locale: $LOCALE"
 
echo "export LANG=$LOCALE" >>/etc/profile.d/locale.sh
 
stat_done
 
 
# Adding persistent network/cdrom generated rules
 
if [ -f "/dev/.udev/tmp-rules--70-persistent-cd.rules" ]; then
 
stat_busy "Adding persistent cdrom udev rules"
 
/bin/cat /dev/.udev/tmp-rules--70-persistent-cd.rules >> /etc/udev/rules.d/70-persistent-cd.rules
 
stat_done
 
fi
 
if [ -f "/dev/.udev/tmp-rules--70-persistent-net.rules" ]; then
 
stat_busy "Adding persistent network udev rules"
 
/bin/cat /dev/.udev/tmp-rules--70-persistent-net.rules >> /etc/udev/rules.d /70-persistent-net.rules
 
stat_done
 
fi
 
 
/bin/dmesg >| /var/log/dmesg.log
 
 
# End of file
 
# vim: set ts=2 noet:
 
 
====/etc/rc.shutdown====
 
#!/bin/bash
 
#
 
# /etc/rc.shutdown
 
#
 
 
. /etc/rc.conf
 
. /etc/rc.d/functions
 
 
# avoid staircase effect
 
/bin/stty onlcr
 
 
echo " "
 
printhl "Initiating Shutdown..."
 
echo " "
 
 
# avoid NIS hanging syslog-ng on shutdown by unsetting the domainname
 
if [ -x /bin/domainname ]; then
 
/bin/domainname ""
 
fi
 
 
if [ -x /etc/rc.local.shutdown ]; then
 
/etc/rc.local.shutdown
 
fi
 
 
if [ "$PREVLEVEL" = "3" -o "$PREVLEVEL" = "5" ]; then
 
# Find daemons NOT in the DAEMONS array. Shut these down first
 
if [ -d /var/run/daemons ]; then
 
for daemon in $(/bin/ls -1t /var/run/daemons); do
 
  if ! in_array $daemon ${DAEMONS[@]}; then
 
stop_daemon $daemon
 
  fi
 
done
 
fi
 
# Shutdown daemons in reverse order
 
let i=${#DAEMONS[@]}-1
 
while [ $i -ge 0 ]; do
 
if [ "${DAEMONS[$i]:0:1}" != '!' ]; then
 
ck_daemon ${DAEMONS[$i]#@} || stop_daemon ${DAEMONS[$i]#@}
 
fi
 
        let i=i-1
 
    done
 
fi
 
 
# Terminate all processes
 
stat_busy "Sending SIGTERM To Processes"
 
/sbin/killall5 -15 &> /dev/null
 
/bin/sleep 5
 
stat_done
 
 
stat_busy "Sending SIGKILL To Processes"
 
/sbin/killall5 -9 &> /dev/null
 
/bin/sleep 1
 
stat_done
 
 
# Write to wtmp file before unmounting
 
/sbin/halt -w
 
 
# Power off or reboot
 
if [ "$RUNLEVEL" = "0" ]; then
 
printsep
 
    printhl "${C_H2}POWER OFF"
 
/sbin/poweroff -d -f -h -i
 
else
 
printsep
 
printhl "${C_H2}REBOOTING"
 
# if kexec is installed and a kernel is loaded, use it
 
[ -x /sbin/kexec ] && /sbin/kexec -e > /dev/null 2>&1
 
/sbin/reboot -d -f -i
 
fi
 
 
# End of file
 
# vim: set ts=2 sw=2 noet:
 
  
 
=Troubleshooting=
 
=Troubleshooting=
Line 319: Line 78:
 
Furthermore, if you're not using the dummy network driver and are attaching to the host's network interface, you'll want to configure the ListenAddress statement of /etc/ssh/sshd_config so that it binds only to the guest's IP address as opposed to 127.0.0.1.
 
Furthermore, if you're not using the dummy network driver and are attaching to the host's network interface, you'll want to configure the ListenAddress statement of /etc/ssh/sshd_config so that it binds only to the guest's IP address as opposed to 127.0.0.1.
  
 +
==SSH immediately terminates the connection==
 +
On my machine, SSH used to authenticate me correctly and log me in, but then immediately drop the connection without an explanation. Consulting /var/log/auth.log revealed the following:
 +
 +
sshd[17899]: pam_limits(sshd:session): Could not set limit for 'nice': Operation not permitted
 +
 +
This is easily fixed by commenting all '''nice''' related lines in /etc/security/limits.conf.
  
 
=Tips & Trick=
 
=Tips & Trick=
 
==Network via dummy adapters==
 
==Network via dummy adapters==
Here, you're either using the dummy module to create virtual network adapters or created interface aliases via /usr/sbin/ip or /usr/sbin/ifconfig. I went for the former and configured the host as such :  
+
Here, you're either using the dummy module to create virtual network adapters or created interface aliases via /usr/sbin/ip. I went for the former and configured the host as such :  
# ''/etc/sysctl.conf'' : net.ipv4.ip_forward=1<br>
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# ''/etc/sysctl.d/99-sysctl.conf'' : net.ipv4.ip_forward=1<br>
 
Modify or add that statement to enable routing on the host
 
Modify or add that statement to enable routing on the host
 
# ''/etc/rc.local''<br>
 
# ''/etc/rc.local''<br>

Revision as of 09:58, 24 September 2013

This article aims to provide all necessary information regarding the creation of a vserver host as well as vserver guests running Arch Linux. This will enable you to setup virtual servers that provide different services as if they were on different machines, with a very little overhead. You can get more information about virtual servers here.

Preparing the Host

To prepare the vserver host environment, you will need to install both a vserver patched kernel, the vserver utilities and their dependencies which are located in the AUR. The required packages are dietlibcAUR, beecryptAUR, kernel26-vserverAUR (not found or linux-vserverAUR orphan), and util-vserverAUR

Paths of Interest

/etc/vservers : configuration root ( reference )

/etc/vservers/.defaults : configuration skeleton used when building new guests
/etc/vservers/.defaults/vdirbase : symlink to the folder containing vserver guests. This defaults to /vservers.
/etc/vservers/<guest name> : guest specific configurations

Preparing the Guests

Vserver will launch guests from subfolders of /etc/vservers/.defaults/vdirbase. As such, creating a new guest system is as simple as installing the required packages in a folder of the host. Furthermore, there's nothing stopping you ( and quite a few things encouraging you ) to mount filesystems to the subfolders of vdirbase and installing your guest in there.

If you plan on doing this often, I highly recommend that you write yourself a little batch script since most of these steps can be automated quite easily.

Preparing the guest installation media

NOTE : This is all heavily inspired from Install From Existing Linux and will therefore be quite brief when not mentioning Vserver specific steps.

Optional: Base variables to follow along with the steps

GuestName= # Name of the guest
GuestRoot=/etc/vservers/.defaults/vdirbase/$GuestName
GuestPackages= # Listing of packages to install via pacman
GuestDisk= # Installation target device
GuestNetDevice= # ex.: eth0, dummy0, etc...
GuestIP= # I think you get it
GuestContext= # Unique identifier for the guest, I go with the last part of the IP

Optional: Preparing the guest disk

  1. Create a LVM Physical Volume, a Volume Group and a Logical Volume ( wiki:LVM )
  2. Create a filesystem on the lvm volume
  3. mkdir $GuestRoot
  4. mount /dev/$GuestDisk $GuestRoot

Optional: Link the host and guest pacman cache

  1. mkdir $GuestRoot/var/cache/pacman/pkg
  2. mount -o bind /var/cache/pacman/pkg $GuestRoot/var/cache/pacman/pkg

Prepare Vserver

  1. vserver $GuestName -m skeleton --context $GuestContext --interface $GuestNetDevice:$GuestIP --flags lock,virt_mem,virt_uptime,virt_cpu,virt_load,sched_hard,hide_netif --initstyle plain
  2. (optional) cd /etc/vservers/$GuestName/interfaces
  3. (optional) cp -r 0 1
  4. (optional) echo 'lo' > dev
  5. (optional) echo '127.0.0.$GuestContext' > ip

Prepare the guest's filesystem

  1. Prepare guest filesystem for the pacman db
    1. mkdir -p /newarch/var/lib/pacman

Install the base system

NOTE : To save some time, it's probably a good idea to create a text file containing all the packages to install and call it via "pacman -S `cat $GuestPackages` -r $GuestRoot" instead of the following :

  1. pacman -S base -r $GuestRoot
  2. Optional: If you want to chroot into the newly created guest so as to install new packages, it might be a good idea to mount a few filesystems required by some packages.
    1. Bind /dev, /proc, /sys to the corresponding directories in $GuestRoot
  3. Modify guest configuration files to enable a smoother boot process
    1. Modify /etc/rc.shutdown by removing anything hardware/clock/mount related. This includes most everything under Saving Random Seed'.
    2. Modify /etc/rc.sysinit by anything hardware/clock/mount related.
    3. Modify /etc/syslog-ng.conf by removing file("/proc/kmsg")

Troubleshooting

Viewing output from vserver $GuestName start / stop

NOTE : For me, this only worked in the actual consoles, not in X.

  1. Make sure that the device /dev/console exists in the guest
    1. If it does not, cp -a /dev/console $GuestRoot/dev/

SSH will not start

I noticed that /dev/null did not always get created properly in my first experimentations. Therefore I did a quick :

  1. cp -a /dev/null $GuestRoot/dev
  2. cp -a /dev/zero $GuestRoot/dev

Furthermore, if you're not using the dummy network driver and are attaching to the host's network interface, you'll want to configure the ListenAddress statement of /etc/ssh/sshd_config so that it binds only to the guest's IP address as opposed to 127.0.0.1.

SSH immediately terminates the connection

On my machine, SSH used to authenticate me correctly and log me in, but then immediately drop the connection without an explanation. Consulting /var/log/auth.log revealed the following:

sshd[17899]: pam_limits(sshd:session): Could not set limit for 'nice': Operation not permitted

This is easily fixed by commenting all nice related lines in /etc/security/limits.conf.

Tips & Trick

Network via dummy adapters

Here, you're either using the dummy module to create virtual network adapters or created interface aliases via /usr/sbin/ip. I went for the former and configured the host as such :

  1. /etc/sysctl.d/99-sysctl.conf : net.ipv4.ip_forward=1

Modify or add that statement to enable routing on the host

  1. /etc/rc.local
modprobe dummy numdummies=$NumberOfGuests
ip link set dev dummy$GuestContext name $GuestName

This provides me with dummy interfaces that I can route / firewall that are all named the same as my guests... yay.

More Resources

Problematic Programs
Make BSD style init SYSV compatible
Vserver tutorial
linux-vserver.org's Installation on ArchLinux
linux-verserver.org's networking tutorial