Difference between revisions of "Arch VServer"

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[[Category:Virtualization]]
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#REDIRECT [[Virtual Private Server]]
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].
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=Preparing the Host=
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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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=Paths of Interest=
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'''/etc/vservers''' : configuration root ( [http://www.nongnu.org/util-vserver/doc/conf/configuration.html ''reference''] )
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: '''/etc/vservers/.defaults''' : configuration skeleton used when building new guests
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:: '''/etc/vservers/.defaults/vdirbase''' : symlink to the folder containing vserver guests. This defaults to /vservers.
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: '''/etc/vservers/<guest name>''' : guest specific configurations
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=Preparing the Guests=
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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.
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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.
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==Preparing the guest installation media==
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'''NOTE''' : This is all heavily inspired from [https://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.
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===Optional: Base variables to follow along with the steps===
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GuestName= # Name of the guest
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GuestRoot=/etc/vservers/.defaults/vdirbase/$GuestName
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GuestPackages= # Listing of packages to install via pacman
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GuestDisk= # Installation target device
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GuestNetDevice= # ex.: eth0, dummy0, etc...
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GuestIP= # I think you get it
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GuestContext= # Unique identifier for the guest, I go with the last part of the IP
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===Optional: Preparing the guest disk===
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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] )
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# Create a filesystem on the lvm volume
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# mkdir $GuestRoot
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# mount /dev/$GuestDisk $GuestRoot
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===Optional: Link the host and guest pacman cache===
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# mkdir $GuestRoot/var/cache/pacman/pkg
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# mount -o bind /var/cache/pacman/pkg $GuestRoot/var/cache/pacman/pkg
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===Prepare Vserver===
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# 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
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# (optional) cd /etc/vservers/$GuestName/interfaces
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# (optional) cp -r 0 1
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# (optional) echo 'lo' > dev
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# (optional) echo '127.0.0.$GuestContext' > ip
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===Prepare the guest's filesystem===
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# Prepare guest filesystem for the pacman db
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## mkdir -p /newarch/var/lib/pacman
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===Install the base system===
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'''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 :
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# pacman -S base -r $GuestRoot
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# 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.
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## Bind /dev, /proc, /sys to the corresponding directories in $GuestRoot
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# Modify guest configuration files to enable a smoother boot process
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## Modify '''/etc/inittab''' by deleting all lines that create the consoles ( agetty )
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## Modify '''/etc/rc.shutdown''' by removing anything hardware/clock/mount related. This includes most everything under ''Saving Random Seed'.
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## Modify '''/etc/rc.sysinit''' by anything hardware/clock/mount related.
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## Create '''/etc/init.d/rc'''
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## Modify '''/etc/syslog-ng.conf''' by removing file("/proc/kmsg")
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## Modify '''/etc/rc.conf''' by removing the networks Daemon.
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# Ensure '''/etc/rc.*''' can be executed: "chmod +x /etc/rc.*"
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===Annexe : Configuration files modified===
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'''/etc/init.d/rc'''
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if [ $1 -eq 3 ]; then
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echo "entering runlevel 3:multi";
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/etc/rc.multi
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fi
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if [ $1 -eq 6 ]; then
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echo "entering runlevel 6:reboot";
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/etc/rc.shutdown
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fi
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if [ $1 -eq 0 ]; then
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echo "entering runlevel 0: shutdown";
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/etc/rc.shutdown
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fi
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if [ $1 -eq 4 ]; then
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echo "entering runlevel 4";
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fi
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if [ $1 -eq 5 ]; then
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echo "entering runlevel 5";
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fi
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if [ $1 -eq 1 ]; then
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echo "entering runlevel 1:single";
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/etc/rc.single
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fi
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if [ $1 -eq 2 ]; then
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echo "entering runlevel 2:multi";
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/etc/rc.multi
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fi
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====/etc/rc.sysinit====
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#!/bin/bash
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#
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# /etc/rc.sysinit
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#
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. /etc/rc.conf
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. /etc/rc.d/functions
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echo " "
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printhl "Arch Linux\n"
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printhl "${C_H2}https://www.archlinux.org"
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printhl "Copyright 2002-2007 Judd Vinet"
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printhl "Copyright 2007-2009 Aaron Griffin"
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printhl "Distributed under the GNU General Public License (GPL)"
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printsep
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# start up our mini logger until syslog takes over
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/sbin/minilogd
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if [ -x /sbin/udevadm ]; then
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stat_busy "Starting UDev Daemon"
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/sbin/udevd --daemon
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stat_done
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else
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# Static /dev, our last resort
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status "Using static /dev filesystem" true
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fi
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# Trigger udev uevents
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if /bin/pidof -o %PPID /sbin/udevd >/dev/null; then
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  stat_busy "Triggering UDev uevents"
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  /sbin/udevadm trigger
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  stat_done
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fi
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  NETFS="nonfs,nonfs4,nosmbfs,nocifs,nocodafs,noncpfs,nosysfs,noshfs,nofuse,nofuseblk,noglusterfs"
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stat_busy "Mounting Local Filesystems"
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/bin/rm -f /etc/mtab*
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# Write /proc, /sys and /dev to /etc/mtab
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if [ -e /proc/mounts ]; then
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/bin/grep -e "rootfs" -e "/proc " -e "/sys " -e "/dev " /proc/mounts >>    /etc/mtab
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fi
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stat_done
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stat_busy "Configuring System Clock"
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if [ ! -f /var/lib/hwclock/adjtime ]; then
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echo "0.0 0 0.0" > /var/lib/hwclock/adjtime
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fi
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if [ "$TIMEZONE" != "" -a -e "/usr/share/zoneinfo/$TIMEZONE" ]; then
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/bin/rm -f /etc/localtime
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/bin/cp "/usr/share/zoneinfo/$TIMEZONE" /etc/localtime
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fi
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if [ -n "$HWCLOCK_PARAMS" ]; then
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/sbin/hwclock --adjust #Adjust for system drift
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/sbin/hwclock $HWCLOCK_PARAMS
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fi
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stat_done
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RANDOM_SEED=/var/lib/misc/random-seed
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if [ -f $RANDOM_SEED ]; then
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stat_busy "Initializing Random Seed"
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/bin/cat $RANDOM_SEED > /dev/urandom
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stat_done
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fi
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stat_busy "Removing Leftover Files"
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/bin/rm -f /etc/nologin &>/dev/null
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/bin/rm -f /etc/shutdownpid &>/dev/null
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/bin/rm -f /var/lock/* &>/dev/null
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/bin/rm -rf /tmp/* /tmp/.* &>/dev/null
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/bin/rm -f /forcefsck &>/dev/null
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(cd /var/run && /usr/bin/find . ! -type d -exec /bin/rm -f -- {} \; )
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: > /var/run/utmp
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/bin/chmod 0664 /var/run/utmp
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# Keep {x,k,g}dm happy with xorg
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/bin/mkdir /tmp/.ICE-unix && /bin/chmod 1777 /tmp/.ICE-unix
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/bin/mkdir /tmp/.X11-unix && /bin/chmod 1777 /tmp/.X11-unix
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stat_done
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#status "Updating Shared Library Links" /sbin/ldconfig
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if [ "$HOSTNAME" != "" ]; then
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status "Setting Hostname: $HOSTNAME" /bin/hostname $HOSTNAME
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fi
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# Set the NIS domain name, if necessary
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[ -f /etc/conf.d/nisdomainname ] && . /etc/conf.d/nisdomainname
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if [ "$NISDOMAINNAME" != "" ]; then
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status "Setting NIS Domain Name: $NISDOMAINNAME" /bin/nisdomainname  $NISDOMAINNAME
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fi
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status "Updating Module Dependencies" /sbin/depmod -A
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# Flush old locale settings
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: >/etc/profile.d/locale.sh
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/bin/chmod 755 /etc/profile.d/locale.sh
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# Set user defined locale
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[ -z "$LOCALE" ] && LOCALE="en_US"
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stat_busy "Setting Locale: $LOCALE"
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echo "export LANG=$LOCALE" >>/etc/profile.d/locale.sh
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stat_done
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# Adding persistent network/cdrom generated rules
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if [ -f "/dev/.udev/tmp-rules--70-persistent-cd.rules" ]; then
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stat_busy "Adding persistent cdrom udev rules"
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/bin/cat /dev/.udev/tmp-rules--70-persistent-cd.rules >> /etc/udev/rules.d/70-persistent-cd.rules
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stat_done
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fi
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if [ -f "/dev/.udev/tmp-rules--70-persistent-net.rules" ]; then
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stat_busy "Adding persistent network udev rules"
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/bin/cat /dev/.udev/tmp-rules--70-persistent-net.rules >> /etc/udev/rules.d /70-persistent-net.rules
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stat_done
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fi
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/bin/dmesg >| /var/log/dmesg.log
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# End of file
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# vim: set ts=2 noet:
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====/etc/rc.shutdown====
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#!/bin/bash
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#
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# /etc/rc.shutdown
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#
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. /etc/rc.conf
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. /etc/rc.d/functions
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# avoid staircase effect
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/bin/stty onlcr
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echo " "
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printhl "Initiating Shutdown..."
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echo " "
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# avoid NIS hanging syslog-ng on shutdown by unsetting the domainname
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if [ -x /bin/domainname ]; then
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/bin/domainname ""
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fi
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if [ -x /etc/rc.local.shutdown ]; then
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/etc/rc.local.shutdown
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fi
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if [ "$PREVLEVEL" = "3" -o "$PREVLEVEL" = "5" ]; then
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# Find daemons NOT in the DAEMONS array. Shut these down first
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if [ -d /var/run/daemons ]; then
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for daemon in $(/bin/ls -1t /var/run/daemons); do
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  if ! in_array $daemon ${DAEMONS[@]}; then
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stop_daemon $daemon
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  fi
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done
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fi
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# Shutdown daemons in reverse order
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let i=${#DAEMONS[@]}-1
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while [ $i -ge 0 ]; do
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if [ "${DAEMONS[$i]:0:1}" != '!' ]; then
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ck_daemon ${DAEMONS[$i]#@} || stop_daemon ${DAEMONS[$i]#@}
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fi
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        let i=i-1
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    done
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fi
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# Terminate all processes
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stat_busy "Sending SIGTERM To Processes"
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/sbin/killall5 -15 &> /dev/null
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/bin/sleep 5
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stat_done
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stat_busy "Sending SIGKILL To Processes"
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/sbin/killall5 -9 &> /dev/null
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/bin/sleep 1
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stat_done
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# Write to wtmp file before unmounting
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/sbin/halt -w
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# Power off or reboot
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if [ "$RUNLEVEL" = "0" ]; then
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printsep
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    printhl "${C_H2}POWER OFF"
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/sbin/poweroff -d -f -h -i
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else
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printsep
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printhl "${C_H2}REBOOTING"
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# if kexec is installed and a kernel is loaded, use it
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[ -x /sbin/kexec ] && /sbin/kexec -e > /dev/null 2>&1
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/sbin/reboot -d -f -i
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fi
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# End of file
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# vim: set ts=2 sw=2 noet:
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=Troubleshooting=
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==Viewing output from vserver $GuestName start / stop==
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'''NOTE : ''' For me, this only worked in the actual consoles, not in X.
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# Make sure that the device /dev/console exists in the guest
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## If it does not, cp -a /dev/console $GuestRoot/dev/
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==SSH will not start==
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I noticed that /dev/null did not always get created properly in my first experimentations. Therefore I did a quick :
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# cp -a /dev/null $GuestRoot/dev
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# cp -a /dev/zero $GuestRoot/dev
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Furthermore, if you're not using the dummy network driver and are attaching to the host's network interface, you'll want to configure the ListenAddress statement of /etc/ssh/sshd_config so that it binds only to the guest's IP address as opposed to 127.0.0.1.
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==SSH immediately terminates the connection==
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On my machine, SSH used to authenticate me correctly and log me in, but then immediately drop the connection without an explanation. Consulting /var/log/auth.log revealed the following:
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sshd[17899]: pam_limits(sshd:session): Could not set limit for 'nice': Operation not permitted
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This is easily fixed by commenting all '''nice''' related lines in /etc/security/limits.conf.
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=Tips & Trick=
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==Network via dummy adapters==
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Here, you're either using the dummy module to create virtual network adapters or created interface aliases via /usr/sbin/ip or /usr/sbin/ifconfig. I went for the former and configured the host as such :
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# ''/etc/sysctl.conf'' : net.ipv4.ip_forward=1<br>
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Modify or add that statement to enable routing on the host
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# ''/etc/rc.local''<br>
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modprobe dummy numdummies=$NumberOfGuests<br>
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ip link set dev dummy$GuestContext name $GuestName
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This provides me with dummy interfaces that I can route / firewall that are all named the same as my guests... yay.
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=More Resources=
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[http://linux-vserver.org/Problematic_Programs Problematic Programs]<br>
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[http://linux-vserver.org/Howto_make_bsd-style_init_sysv-compatible Make BSD style init SYSV compatible]<br>
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[http://www.cedarcreeksoftware.com/an-even-easier-linux-vserver-tutorial.html Vserver tutorial]<br>
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[http://linux-vserver.org/Installation_on_ArchLinux linux-vserver.org's Installation on ArchLinux]<br>
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[http://wiki.linux-vserver.org/Networking_vserver_guests linux-verserver.org's networking tutorial]<br>
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<!-- vim: set ft=Wikipedia: -->
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Latest revision as of 02:15, 6 June 2015