Vnx-rootfsfedora

How to create a Fedora root filesystem for VNX

Follow this procedure to create a fedora based root filesystem for VNX. The procedure has been tested with Fedora 14.

Basic installation

• Create the filesystem disk image:

qemu-img create -f qcow2 root_fs_fedora-base.qcow2 5GB

• Get Fedora installation DVD (use the complete DVD; do not use the Live version, as it seems the installation wizard does not include the customization menu). For example:

wget ftp://ftp.rediris.es/mirror/fedora/14/Fedora/i386/iso/Fedora-14-i386-DVD.iso
cp Fedora-14-i386-DVD.iso /almacen/iso

• Create a libvirt XML definition (root_fs_freebsd.xml) containing the virtual machine description:

<domain type='kvm'>
  <name>Fedora</name>
  <memory>524288</memory>
  <vcpu>1</vcpu>
  <os>
    <type arch="i686">hvm</type>
    <boot dev='hd'/>
    <boot dev='cdrom'/>
  </os>
  <features>
     <pae/>
     <acpi/>
     <apic/>
  </features>
  <clock sync="localtime"/>
  <devices>
    <emulator>/usr/bin/kvm</emulator>
    <disk type='file' device='disk'>
      <source file='/usr/share/vnx/filesystems/root_fs_fedora-base.qcow2'/>
      <target dev='hda'/>
    </disk>
    <disk type='file' device='cdrom'>
      <source file='/almacen/iso/Fedora-14-i386-DVD.iso'/>
      <target dev='hdb'/>
    </disk>
    <interface type='network'>
      <source network='default'/>
    </interface>
    <serial type="pty">
      <target port="1"/>
    </serial>
    <console type="pty">
      <target port="1"/>
    </console>
    <graphics type='vnc'/>
  </devices>
</domain>

Note: change "source file=" lines to whatever fits your case (use full paths).

• Start the virtual machine with and access its console with:

virsh create root_fs_fedora.xml
virt-viewer Fedora

• Follow Fedora installation menus to install:
• A "minimal" system, if you want a server rootfs without user interface
• One of the other options (e.g "web server", "desktop system", etc) if you want a system with graphical user interface
• Once installation is finished, stop the machine, edit root_fs_fedora.xml file and comment the following line in cdrom disk specification:
• Start the virtual machine again with:

virsh create root_fs_fedora.xml
virt-viewer Fedora

Configuration

• Update the system and install additional packages

yum update
yum install perl perl-XML-DOM acpid udisks

Note: if yum fails, check that the network is working. Maybe you will have to manually execute "dhclient eth0", at least in the case of a minimal installation.

• Install VNX autoconfiguration daemon:
• From the host execute:

/usr/share/vnx/bin/vnx_update_aced Fedora /usr/share/vnx/aced/vnx-aced-lf-0.1b.tgz 

• From the virtual machine console:

ln -s /media/CDROM /media/cdrom
udisks --mount /dev/sr0
perl /media/cdrom/install_vnxaced

• Enable login on the first serial line by creating a file named /etc/init/serial-ttyS0.conf with the following content:

#This service maintains a getty on /dev/ttyS0.
start on stopped rc RUNLEVEL=[2345]
stop on starting runlevel [016]
respawn
exec /sbin/agetty /dev/ttyS0 9600 vt100-nav

• Besides, you have to add ttyS0 to /etc/securetty file if you want to login root on that console:

echo "ttyS0" >> /etc/securetty

• If you have chosen a "minimum installation", activate network services (they are disabled by default):

chkconfig --level 3 network on

• Optionally:
• Install other services needed, for example, an apache server:

yum install httpd
update-rc.d -f apache2 remove   # to avoid automatic start

• Or, if using a "minumum installation", install network utilities:

yum install telnet wget openssh-clients

• If you want automatic login, just edit /etc/gdm/custom.conf and add the following lines:

AutomaticLoginEnable=true
AutomaticLogin=vnx

• Disable the firewall. Firewall is enabled by default; that could be problematic for testing purpose systems. If desired, disable it graphically in "System|Administration|Firewall" option, or using the following command from the command line:

chkconfig iptables off

• Create a file /etc/vnx_root_fs_version to store version number and informacion about modification:

VER=v0.21
OS=Fedora 14
DESC=Basic Fedora 14 root-filesystem without GUI

• Create a script named /usr/local/bin/vnx_halt:

#!/bin/bash
# Clean yum cache
yum clean all
# Delete /etc/resolv.conf
rm -f /etc/resolv.conf
# Clean command history
rm -f /root/.bash_history
# Delete udev net rules files:
rm -f /etc/udev/rules.d/70-persistent-net.rules
while true; do
    # Ask for a message to save in /etc/vnx_root_fs_version file
    echo    "** Save a log message in /etc/vnx_root_fs_version file "
    echo -n "** describing the modifications done? "
    read -n 1 -p "[y/n] " answer
    echo ""
    case $answer in
        [Yy]* )
                echo "** Log message (1 line maximum):"
                read logmsg
                DATE=`date`
                echo "MODDATE=$DATE" >> /etc/vnx_root_fs_version
                echo "MODDESC=$logmsg" >> /etc/vnx_root_fs_version
                break;;
        [Nn]* ) break;;
        * )     echo "** Error: please answer 'y' or 'n'.";;
    esac
done
# Halt the system
halt -p

• Give the script execution permissions:

chmod +x /usr/local/bin/vnx_halt

• Stop the machine with that script:

vnx_halt

Installing additional software

To install additional software or modify your root filesystem, you just have to start it as described above and make the operations required on the filesystem.

• Start the virtual machine (directly using virsh or the vnx_modify_rootfs utility):

 /usr/share/vnx/bin/vnx_modify_rootfs root_fs_fedora.xml 

• Install the software:

yum install ...

• Stop the machine with:

vnx_halt