Creating a CentOS 5.0 Template

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  1. Install a system (virtual or physical) with the default CentOS installation that you wish to package. This could be a minimal distro or the default distro or even something custom.
    1. It's generally quicker to bootstrap a CentOS system on another yum/rpm-based, or Debian based system by following the instructions in [1]
  2. Once the OS has been installed, you need to tar the contents of the OS.
    1. First, create a file called /tmp/exclude and add the following lines to it:
    .bash_history
    lost+found
    /dev/*
    /mnt/*
    /tmp/*
    /proc/*
    /sys/*
    /usr/src/*
    1. Now, tar the OS file up by typing: tar --numeric-owner -czvf /tmp/centos-5.0-<ARCH>-<DISTRO>-image.tar.gz -X /tmp/exclude / where <ARCH> represents the system architecture (i386 or
    x86_64) and <DISTRO> represents the distribution (default, minimal, etc.).
    1. Now transfer the file over to the OpenVZ server into /vz/template/cache folder.
  3. On the OpenVZ server create a “dummy” container by creating a folder called /vz/private/50
    and copying the /etc/vz/conf/ve-vps.basic.conf-sample to /etc/vz/conf/50.conf.
    NOTE: 50 is the CTID for the container. You can choose any unused CTID on the OpenVZ server.
  4. Now create a new folder called /vz/template/centos/5/<ARCH>/config again where
    <ARCH> represents the system architecture.
  5. Create a file in the folder called rpm and add the following line:
    43
  6. Create a file called yum.conf in the folder and add the following lines:
    [main]
    cachedir=/vz/template/centos/5/<ARCH>/yum-cache/
    reposdir=/dev/null
    installonlypkgs=
    [centos5-base]
    name=CentOS 5 - <ARCH> - Base
    baseurl=http://mirror.centos.org/centos/5/os/<ARCH>/
    enabled=1
    gpgcheck=1
    [centos5-updates-released]
    name=CentOS 5 - <ARCH> - Released Updates
    baseurl=http://mirror.centos.org/centos/5/updates/<ARCH>/
    enabled=1
    gpgcheck=1
  7. Copy /etc/vz/dists/centos-4.conf to /etc/vz/dists/centos-5.conf.
  8. Copy /vz/template/centos/4/i386/config/minimal.list to /vz/template/centos/5/i386/config/minimal.list.
  9. Change to the /vz/private/50 folder and then run the command gunzip –dc /vz/template/cache/centos-5-<ARCH>-<DISTRO>-image.tar.gz | tar –xvf – to unpack the base image to the folder.
  10. Make sure you are in the /vz/private/50 folder.
  11. Edit etc/shadow and remove the replace the root password with !! instead of the hashed value.
  12. Edit the etc/inittab file and comment out the lines that respawn /sbin/mingetty on tty1 through tty6. Just put a # at the beginning of the line.
  13. Remove the etc/mtab file and then create a symbolic link by typing ln -s /proc/mounts etc/mtab.
  14. Remove all of the lines from etc/fstab except for the line that mounts /dev/pts.
  15. Edit etc/rc.d/rc.sysinit and comment out the line that starts /sbin/start_udev by placing a # at the beginning of the line.
  16. Now create device nodes by typing:
    mknod dev/ptmx c 5 2
    mkdir dev/pts
    /sbin/MAKEDEV –d/vz/private/50/dev ttyp ptyp
    mknod dev/null c 1 3
    mknod -m 644 dev/random c 1 8
    mknod dev/urandom c 1 9
  17. Create the var/lock/rpm folder.
  18. If you wish to disable IPv6, do the following:
    1. Edit etc/sysconfig/network and set NETWORKING_IPV6 to no.
    2. Add the following lines to etc/modprobe.d/blacklist:
    blacklist ipv6
    blacklist net-pf-10
  19. Disable any physical NICs by modifying the etc/sysconfig/network-scripts/ifcfg-ethX files (where X is the interface number starting from 0) and setting ONBOOT to no.
  20. Check etc/sysconfig/init to see if PROMPT=yes, and then change to no. Otherwise when startup init script rc will enter interactive mode and wait there forever
  1. Now you’re ready to start the template. Type vzctl start 50 and wait for it to start.
  2. You can install additional packages into the container by typing vzyum 50 install <package> at the prompt where <package> represents the name of the software package you wish to install.
  3. Finally, you should turn off unnecessary services.
    1. Enter the container by typing vzctl enter 50.
    2. View the services that are set to run at startup by typing chkconfig --list | grep 5:on.
    3. Disable any unwanted service by typing chkconfig --levels 2345 <service> off where <service> represents the service to disable.
    Services that you can (and should) turn off without harm are acpid, apmd, kudzu, and microcode_ctl.
  4. Exit the container by typing exit at the prompt.
  5. Stop the container by typing vzctl stop 50.
  6. Make sure you are in the /vz/private/50 folder.
  7. Finally, package up the new template by typing tar –czvf /vz/template/cache/centos-5-<ARCH>-<DISTRO>.tar.gz ./.
  8. The template is ready for use.
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