/ 
Tapper-Doc-3.000010
/ Tapper::Doc::Start::PrepareNFSroot

NAME

Tapper::Doc::Start::PrepareNFSroot - Step-by-step instructions how to set up a Tapper::Installer image bootable from NFS

Intro

The Tapper::Installer needs an NFS root image. This document describes how to change a Debian Lenny image supplied with Tapper to become Installer root.

Remove network setup from init

The network is set up by the kernel at startup. Usually, there will be a network setup script started by init. An additional networking would deactivate the already running interface and make the NFS root unavailable and therefore the boot process stop.

Enable console login

Install a getty tool (e.g. getty), put the following line into /etc/inittab to enable login from serial console: s0:12345:respawn:/sbin/getty 115200 ttyS0 vt100 Grant permission for console login by adding ttyS0 to /etc/securetty.

Set NFS read-only

We suggest to use a readonly NFS for installation. When anything goes wrong this reduces the risk that the installer will damage your installation system. This benefit is usually worth the extra effort that comes with a readonly NFS root for the Installer.

To use a readonly NFS two changes are needed. To make the kernel mount the root NFS file system read only the grub config needs to contain "root=/dev/nfs ro" in the kernel command line. This is not enough because during init the root filesystem is remounted rw unless requested otherwise. In the debian image provided with the Tapper starter package this is done by setting "rootmode=ro" in /etc/init.d/checkroot.sh. Alternatively, you can tell your NFS server to export the file system read_only.

Even on a readonly root NFS some directories need to be writeable. This includes especially /tmp but also some parts of /var like /var/log.

proc /proc proc defaults 0 0 sysfs /sys sysfs defaults 0 0 tmpfs /tmp tmpfs defaults 0 0

ramfs /var/log ramfs defaults 0 0 ramfs /var/lock ramfs defaults 0 0 ramfs /var/run ramfs defaults 0 0 ramfs /var/spool ramfs defaults 0 0

Set up Perl

Use a compiled own perl to get some advantages. You can set your own options like threads/no threads and your perl won't interfere with possible distro tools using perl. The following paragraph describes how to use a separate Tapper perl on the attached debian image.

Install perl using perlbrew

cpan App::perlbrew
PERLBREW_ROOT=/opt/tapper/perl perlbrew init
add "source /opt/tapper/perl/etc/bashrc" to your bashrc (as
instructed by perlbrew
install perl-5.12.3 (or any version >= 5.10.1)
 use -D, -U and -A to pass switches to configure
switch to your new perl
configure your cpan

Install Tapper::Installer

cpan Tapper::Installer

Create an init.d file to start tapper-installer-client.pl. The start file is found at /opt/tapper/perl/perls/current/bin/tapper-installer-client.pl

** an example script for Debian can be found at the end of this document

Activate the startup script:

update-rc.d tapper defaults        # Debian
chmod +x /etc/init.d/tapper

If you are on a Redhat or Suse system you can use the following instead:

insserv /etc/init.d/tapper         # Suse
chkconfig --add /etc/init.d/tapper # RedHat

Create the required files and directories

mkdir /mnt/target/
mkdir /mnt/guests
mkdir /data/tapper

Install a log4perl config see doc/oss/etc/log4perl.cfg for an example

Since /etc/tapper is not writable on a readonly NFS we need to symlink it into tmpfs:

ln -sf /tmp/tapper /etc/tapper