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CentOS 4 VServer How To

(originally based off of the Fedora Core 3 How To)

This will guide you through the process of setting up Linux-VServer on CentOS 4, meaning turning it into a host and creating different types of vservers on that host.

A. Requirements

What do I need to get started?
- CentOS 4 installed, but not yet in production
- Internet connection for downloads
Do I have to have multiple offical IP Addresses?
- No, this document uses all internal IP addresses for demonstration purposes. When going into production, see other docs for the method you choose to use.

B. New VServer-enabled kernel

Get and compile kernel
The CentOS default Kernel release is highly patched already and thus are not compatible with the patches supplied by linux-vserver.org. For this reason, we are going to use a vanilla-kernel (read: an unmodified original linux kernel) from kernel.org.

Ftp to a local kernel.org mirror (usually the url ftp://ftp.<country-code>.kernel.org should work)

Go to /pub/linux/kernel/v2.6/

Get the latest linux-2.6.??.tar.bz2 ( where ?? is the kernel subversion, by the time of this writing, the latest is 2.6.11.5)

Get the matching .sign file

Once both files are downloaded, verify the pgp signature of the archive

Add the linux kernel !OpenPGP signature to your local gpg by running ''gpg ```--```keyserver wwwkeys.pgp.net ```--```recv-keys 0x517D0F0E'' 
Now verify the kernel: gpg --verify linux-2.6.??.tar.bz2.sign linux-2.6.??.tar.bz2 ( for more details about this, visit [Kernel.org])

Move the kernel archive to /usr/src (mv linux-2.6.??.tar.bz2 /usr/src/) and unpack it (tar -xjf linux-2.6.??.tar.bz2)

Download [the Patchset] now (by the time of this writing, the latest version is 1.9.5 against kernel 2.6.11.5)

Run the patch against the kernel from within /usr/src ( patch -p0 < patch-2.6.??-vs1.9.5.diff )

Now enter the linux-2.6.?? source directory and run make menuconfig. You need to make sure all the required vserver options are enabled, besides that, build a kernel as usual.

Next, run 'make', then 'make modules_install', then 'make install'

CentOS, properly modifies the grub.conf file for the new kernel, but we still need to make some more changes:

Fix /etc/fstab

CentOS uses LABEL, which is not compatible with a vanilla kernel

Run 'mount' to see what drives are pointing where

Change the corresponding lines in /etc/fstab to point to the real device name:

Before:

LABEL=/                 /                       ext3    defaults        1 1
LABEL=/boot1            /boot                   ext2    defaults        1 2
none                    /dev/pts                devpts  gid=5,mode=620  0 0
none                    /dev/shm                tmpfs   defaults        0 0
none                    /proc                   proc    defaults        0 0
none                    /sys                    sysfs   defaults        0 0
LABEL=SWAP-hda2         swap                    swap    defaults        0 0
/dev/hdb                /media/cdrom            auto    pamconsole,exec,noauto,managed 0 0
/dev/fd0                /media/floppy           auto    pamconsole,exec,noauto,managed 0 0

Mount:

/dev/hda3 on / type ext3 (rw)
none on /proc type proc (rw)
none on /sys type sysfs (rw)
none on /dev/pts type devpts (rw,gid=5,mode=620)
usbfs on /proc/bus/usb type usbfs (rw)
/dev/hda1 on /boot type ext2 (rw)
none on /dev/shm type tmpfs (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)

After:

/dev/hda3               /                       ext3    defaults        1 1
/dev/hda1               /boot                   ext2    defaults        1 2
none                    /dev/pts                devpts  gid=5,mode=620  0 0
none                    /dev/shm                tmpfs   defaults        0 0
none                    /proc                   proc    defaults        0 0
none                    /sys                    sysfs   defaults        0 0
/dev/hda2               swap                    swap    defaults        0 0
/dev/hdb                /media/cdrom            auto    pamconsole,exec,noauto,managed 0 0
/dev/fd0                /media/floppy           auto    pamconsole,exec,noauto,managed 0 0

Fix /boot/grub/grub.conf

This file also needs to be modified for the same reasons

Change all lines that use LABEL in /boot/grub/grub/conf to point to the real device name

Change:

        kernel /vmlinuz-2.6.9-5.0.3.EL ro root=LABEL=/

To:

        kernel /vmlinuz-2.6.9-5.0.3.EL ro root=/dev/hda1

Disable SELinux

SELinux conflicts with Linux-VServer. Disable it in /etc/selinux/config (SELINUX=disabled)

Reboot

If it boots, you did it right, otherwise, go back and check everything.

C. Get the tools

Download [util-vserver](v0.30.205)

Configure it with the following options:

./configure --prefix=/usr --sysconfdir=/etc --with-vrootdir=/vservers

make, make check, make install

D. Adding CentOS 4 Support into the tools

cd /usr/lib/util-vserver/distributions

cp fc3 centos4

cd centos4

mkdir pubkeys

cp /usr/share/rhn/RPM-GPG-KEY-centos4 ./pubkeys/ (Should be there from a properly updated CentOS install)

ln -s ../redhat/initpre .

ln -s ../redhat/initpost .

cd pkgs

rm -f 01 02 03

vi 01 and put the contents of this into it: http://linux-vserver.org/CentOS_min_install

cd ../yum

vi yu/yum.conf and replace with:

[main]
cachedir=@YUMCACHEDIR@
reposdir=@YUMETCDIR@/yum.repos.d
debuglevel=2
logfile=@YUMLOGDIR@/log
pkgpolicy=newest
distroverpkg=centos-release
tolerant=1
exactarch=1
retries=20
obsoletes=1
gpgcheck=1

cd yum.repos.d

rm -f *.repo

cp /etc/yum.repos.d/CentOS-Base.repo .

E. VServer creation

Build a new vserver