Diskless image configuration - manual setup

Revision as of 09:55, 9 June 2014 by WikiFreak (talk | contribs)

This article explains how to setup MANUALLY a netboot image.


Instead of manual operations you can use some config managers such as Puppet or Chef.



Get distribution's content

Debian 7.x 

cd /nfs/wheezy
debootstrap wheezy /nfs/wheezy


Ubuntu 14.04 

cd /nfs/trusty
debootstrap trusty /nfs/trusty



Access distribution

This will "mount" the system: 

# Debian 7.x
chroot /nfs/wheezy/

# Ubuntu 14.04
chroot /nfs/trusty/

From here you can perform operation as if you were on a separate machine.

Only the current distribution (= the client one) will be affected.


Setup

Adjust default login/password

First of all, you have to create / adjust the default user. 

# Add new user
adduser <username>
# Add user to sudoers group
usermod -a -G sudo <username>


Now you can use that user: 

su <username>
sudo -s

You can check that you really are in the "Virtual machine" by checking "/srv/". It should be empty !


- Note -

On Debian distribution you have to install "sudo" manually. It's not in the defaults packages.


Update sources.list and install key packages

Your client need to have some key packages in order to work. Without these package even the NetBoot will fail !!


First of all: edit your sources.list 

apt-get install vim
vim /etc/apt/sources.list


Put the following: 

### Custom repositories list
#
# May 2014 - Guillaume Diaz
# This is an ajdustement of the default "debootstrap" sources.list
# This is required to provided update, security and advanced tools to all our clients
#


#########################
# Debian 7.x [Wheezy]
#########################
deb http://ftp.se.debian.org/debian stable main contrib
deb http://ftp.debian.org/debian/ wheezy-updates main contrib
deb http://security.debian.org/ wheezy/updates main contrib



#########################
# Ubuntu 14.04 LTS [Trusty]
#########################
# Official repositories
deb http://se.archive.ubuntu.com/ubuntu/ trusty main restricted universe multiverse
deb http://se.archive.ubuntu.com/ubuntu/ trusty-updates main restricted universe multiverse
deb http://security.ubuntu.com/ubuntu trusty-security main restricted universe multiverse

# Official updates 
deb http://se.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse

# Canonical partners
#deb http://archive.canonical.com/ubuntu trusty partner

# Community partners
#deb http://extras.ubuntu.com/ubuntu trusty main


Update your package list: 

apt-get update && apt-get upgrade


Now, you can install the basic programs: 

# NFS client. This is ABSOLUTELY MANDATORY ! That's the only way to mount the /root
apt-get install nfs-common
apt-get install initramfs-tools

# NFS is a bit low, and if you're using many client it might result in time faults. 
# You must install NTP to overcome this !!
apt-get install ntp ntpdate

# Basic set of utilities
apt-get install unzip zip
apt-get install make autoconf automake cpp gcc build-essential
apt-get install htop
apt-get install python3

# Advanced APT manager (require to add repository from command line)
apt-get install software-properties-common python-software-properties


# JAVA (that is required for my application)
# Depending on your target usage you might not need it.


##### Ubuntu repository
add-apt-repository ppa:webupd8team/java 

##### Debian repository
echo "deb http://ppa.launchpad.net/webupd8team/java/ubuntu trusty main" | tee -a /etc/apt/sources.list
apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys EEA14886

##### Installation
apt-get update && apt-get upgrade
apt-get install oracle-java7-installer oracle-jdk7-installer


Adjust bash and vim configuration

Edit your VIM configuration: 

vim /etc/vim/vimrc

Enable dark background + set nu + set ruler


Edit your bash configuration files to adjust the alias and enable auto-completion: 

vim /etc/bash.bashrc
vim /home/<username>/.bashrc
vim /root/.bashrc


Edit mount points (/etc/fstab)

You must edit the mount points to get the client working! 

vim /etc/fstab


# /etc/fstab: static file system information.
#
# <file system> <mount point>   <type>  <options>                                      <dump>  <pass>
proc            /proc           proc    defaults                                        0       0
/dev/nfs        /               nfs     defaults,ro,noatime                             1       1
none            /tmp            tmpfs   defaults,rw,noexec,nosuid,size=512M             0       0
none            /var/run        tmpfs   defaults,rw,noatime,noexec,nosuid               0       0
none            /var/lock       tmpfs   defaults,rw,noatime,noexec,nosuid               0       0
none            /var/tmp        tmpfs   defaults,rw,noexec,nosuid,size=128M             0       0
none            /var/log        tmpfs   defaults,rw,noexec,nosuid,size=128M             0       0
none            /run/shm        tmpfs   nodev,nosuid,noexec,size=256M                   0       0


- Notes -

  • There is no swap as the /tmp is already a RAMdisk and that should be enough.
  • Notice the "none" + "tmpfs" for all mount point except the root "/" and "proc"
  • ro - For Read Only mount point
  • noatime - To speed up things by skipping the file access time registration. That will skip some write operations but it make it harder to know what has been accessed when. That's perfect for /tmp but it should not be set anywhere else.
  • realtime - only update file timestamp if the file or directory has been modified since the last atime update. You might choose to use ‘noatime’ on most of your filesystems but leave /var/spool and /tmp as ‘relatime’:
  • noexec - To prevent people from running executables in /tmp. Some rootkits do that. This flag might cause trouble for some legitimate applications so be sure to test everything properly after setting this flag.
  • nosuid - To prevent the setuid bit from being set on files in /tmp.
  • no size on "/var/run" and "/var/lock" : it's better to let the system managed that


As "/var/tmp" is used to preserve temporary data across reboot - and due to the fact that it's a temp RAMdisk - it should not be used! However, to prevent bugs it's safer to allow some little space.


Beware "/var/log" will be reset at each reboot! So you absolutely need to setup some kind of central log solution - using logstash for instance.


Setup network interfaces

Even though you're using the NetBoot process you still have to register some interfaces! More important, the NetBoot disable the loopback "lo" - so you should better add that one back! 

# Adjust "xxxx" by your distribution name
vim /nfs/xxxx/etc/network/interfaces


Add: 

auto lo
iface lo inet loopback


Clear hostname

By default your client will have the same hostname as the server due to the "deboostrap" installation. :(


You MUST clean that in order to retrieve the name from your DNS. 

vim /nfs/xxxx/etc/hostname

That file must be empty.


Setup correct DNS

Your network configuration might change in the future, therefore you don't want to save any hard DNS reference in the client!

You have to edit resolv.conf configuration and make it clean.


Both following files should be empty - if not then you have to clean them !

  • /nfs/xxxx/etc/resolvconf/resolv.conf.d/base
  • /nfs/xxxx/etc/resolvconf/resolv.conf.d/orginal


You can also clean the resolv.conf that was generated by deboostrap: 

vim /nfs/xxxx/etc/resolv.conf

You can delete all DNS references from that file.


Keyboard configuration

You have to set your keyboard configuration to use something else than the US layout as default. 

vim /etc/default/keyboard


Adjust the lang and keyboard size: 

XKBMODEL="pc105"
XKBLAYOUT="se"
XKBVARIANT=""
XKBOPTIONS=""


Now you can run the configuration utility: 

dpkg-reconfigure keyboard-configuration



Exit client distro

Exit until your reach your starting point. 

exit
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