Difference between revisions of "Diskless netboot"
 
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Diskless server / workstation using netboot
+
[[Category:Linux]]
  
  
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NFS is a technology that allow you to share some files and folders over the network. So:
+
==Target folder tree (server side)==
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* All the clients will share the installation, configuration files and so on.
 
−
* Each client will run a dedicated instance of the operating system
 
−
* Logs will be centralized on the common NFS server - so we don't loose data on each reboot.
 
  
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You must have a working DHCP server + NetBoot before starting this part.
+
This is how we'll setup our files and folders:
  
 +
<syntaxhighlight lang="bash">
 +
# TFTP root
 +
/tftpboot/                                 
  
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Requirements:
+
###############
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* [[DHCP server]]
+
# Network bootable image(s) using NFS technology
−
* [[NetBoot server]]
+
################     
  
 +
#### Boot file           
 +
/tftpboot/pxelinux.0                  # Initial boot file - only use to load the PXE NetBoot manager
 +
/tftpboot/{menu.c32 || vesamenu.c32}  # PXE interactive menu managers (text or graphical)
 +
/tftpboot/pxelinux.cfg/                # PXE configuration(s)
 +
/tftpboot/pxelinux.cfg/default        # default PXE configuration
  
 +
#### Kernel file
  
−
=Installation=
+
/tftpboot/images/     
  
 +
# Debian 7.x [Wheezy]
 +
/tftpboot/images/wheezy/ 
 +
/tftpboot/images/wheezy/vmlinuz
 +
/tftpboot/images/wheezy/initrd.img
  
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'''NFS support'''
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# [X]Ubuntu 14.04 [Trusty]
−
<syntaxhighlight lang="bash">
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/tftpboot/images/trusty/ 
−
apt-get install nfs-kernel-server nfs-common
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/tftpboot/images/trusty/vmlinuz
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</syntaxhighlight>
+
/tftpboot/images/trusty/initrd.img
  
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'''Debootstrap (manage netboot image)'''
 
−
<syntaxhighlight lang="bash">
 
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apt-get install debootstrap
 
−
</syntaxhighlight>
 
  
 +
#### NFS
 +
# This is where the runnable will be. Each image will be in a dedicated folder.
 +
/nfs/                   
  
 +
# Debian 7.x [Wheezy]
 +
/nfs/wheezy/ 
  
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=NFS server setup=
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# Ubuntu 14.04 [Trusty]
 +
/nfs/trusty/
 +
</syntaxhighlight>
  
  
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==Preparation==
 
  
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You have to create a dedicated folder on your server where you will host the client image.
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==Client overview==
  
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<syntaxhighlight lang="bash">
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Each client must have, at least, 4 Go of RAM.
−
mkdir -p /srv/nfsroot
 
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chmod -R 777 /srv/nfsroot
 
−
</syntaxhighlight>
 
  
  
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==Configuration==
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===4 GO RAM configuration===
  
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The NFS configuration is done in the '''/etc/exports''' file
+
This is how we're gonna populate the client:
  
−
<syntaxhighlight lang="bash">
+
[[File:Client_composition.png|480px|NetBoot client RAM overview - 4Go]]
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vim /etc/exports
 
−
</syntaxhighlight>
 
  
  
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Add something like that:
+
As you can see, each client will have some space dedicated for swap + some RAMdisk to allow writing in /var, /tmp and /proc.
  
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<syntaxhighlight lang="bash">
 
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  /srv/nfsroot      192.168.2.*(ro,no_root_squash,async,insecure,no_subtree_check)
 
−
</syntaxhighlight>
 
  
 +
Configuration of a '''4Go RAM''' disk:
 +
* No swap
 +
* Local TMPFS (read/write for /dev, /tmp, ...) : 1 Go
 +
** /tmp      = 512 M
 +
** /var/tmp  = 128 M
 +
** /var/log  = 128 M
 +
** /var/run  = 8 M
 +
** /var/lock = 8 M
 +
** /run/shm  = 256 M
 +
* O.S (NFS read only) : all the rest ~ 2.8 Go
 +
* Common share (NFS read write) : ''Remote disk''
  
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Adjust "192.168.2.*" to your own network address
 
  
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* rw : Allow clients to read as well as write access
 
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* ro : Read only access
 
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* insecure : Tells the NFS server to use unpriveledged ports (ports > 1024).
 
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* no_subtree_check : If the entire volume (/users) is exported, disabling this check will speed up transfers.
 
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* async : async will speed up transfers.
 
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* no_root_squash: This phrase allows root to connect to the designated directory.
 
  
 +
===2 Go===
  
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- NOTE -
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Due to budget restriction we might encounter some low memory machines with only 2 Go...
  
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It's always a good idea to use Read-Only if you plan to share this disk.
 
  
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That will avoid user to mess with your image!
+
This is how we're gonna populate the client:
  
 +
[[File:Client_mount_points_2Go.png|480px|NetBoot client RAM overview - 2Go]]
  
  
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==Security==
+
In case of '''2Go RAM''' then you have to use some tricks:
 +
* No swap
 +
* O.S (NFS read only) : ~ 1.2 Go
 +
* Common share (NFS read write) : ''Remote disk''
 +
* Local TMPFS (read/write for /dev, /tmp, ...) : all the rest
 +
** /tmp      = 372 M
 +
** /var/tmp  = auto
 +
** /var/log  = 128 M
 +
** /var/run  = auto
 +
** /var/lock = auto
 +
** /run/shm  = auto
  
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Like TFTP, this part is insecure !
 
  
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You must restrict the access to your NFS server by a firewall script and filtering BEFORE reaching the LAN !
 
  
 +
==How big is the client image ?==
  
 +
By default the ''deboostrap'' Ubuntu 14.04 LTS image is 239 Mo. With the applications we're gonna use that size will increase to about 1 or '''1.3 Go''' depending if you copy (or not) the kernel sources. It may even take 1.6 Go if you're using XFCE frontend.
  
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NFS is using dynamic ports numbers because it runs over '''rpcbind'''. Making NFS using specifics port is a pain in the ass !! :(
 
  
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So, instead of that you should allow your LAN communication.
 
  
 +
=NFS client image=
  
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<syntaxhighlight lang="bash">
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There are different way to setup a NFS client image.  
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    IPTABLES=`which iptables`
 
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    LAN_ADDRESS="192.168.2.0/24"
 
  
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    # Allow LAN communication
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The main ones are:
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    $IPTABLES -A INPUT -s $LAN_ADDRESS -d $LAN_ADDRESS -m state ! --state INVALID -j ACCEPT
 
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    $IPTABLES -A OUTPUT -s $LAN_ADDRESS -d $LAN_ADDRESS -m state ! --state INVALID -j ACCEPT
 
  
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</syntaxhighlight>
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* Manually
 +
** debootstrap
 +
** copying the install from your server
 +
** Manual install on a client, then, when the system is ready, copy everything to the NFS share
  
 +
* Using script and software like "Puppet" or "Chef"
  
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==Management==
 
  
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<syntaxhighlight lang="bash">
 
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service nfs-kernel-server {status|start|stop|restart}
 
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</syntaxhighlight>
 
  
 +
==Setup client distribution==
  
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==Test the server==
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You have to create one target for each distribution you want to serve:
  
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Install the NFS v4 client:
 
 
<syntaxhighlight lang="bash">
 
<syntaxhighlight lang="bash">
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apt-get install nfs-common  
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mkdir -p /nfs/trusty
 +
mkdir -p /nfs/wheezy
 +
mkdir -p /nfs/common
 
</syntaxhighlight>
 
</syntaxhighlight>
  
  
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To mount the default path:
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- NOTES -  
−
<syntaxhighlight lang="bash">
 
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mount -t nfs nfs-server:/ /mnt
 
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</syntaxhighlight>
 
  
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You'll see: "/mnt/srv/nfsroot"
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* The folder name should match your NetBoot settings. Folder name = a LABEL in the NetBoot config.
  
 +
* The folder name should match a Linux (Debian like) distribution name
  
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It's better to do:
 
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<syntaxhighlight lang="bash">
 
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mount -t nfs nfs-server:/srv/nfsroot /mnt
 
−
</syntaxhighlight>
 
  
  
 +
==Configure client distribution==
  
 +
* Manual configuration: [[Diskless image configuration - manual setup]]
  
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=NFS client image=
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* Automatic [Puppet || Chef] configuration: [[Diskless image configuration - script setup]]
  
−
There are different way to setup a NFS client image.
 
  
−
The main ones are:
 
−
* debootstrap
 
−
* copying the install from your server
 
−
* Manual install on a client, then, when the system is ready, copy everything to the NFS share
 
  
  
  
−
==Debootstrap: setup client distribution==
+
==Backup distribution==
  
 +
You can create an archive of your current distribution for later restore / re-use.
  
−
===Setup distribution folder===
 
  
−
You have to create one target for each distribution you want to serve:
+
===Compression===
  
 
<syntaxhighlight lang="bash">
 
<syntaxhighlight lang="bash">
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mkdir -p /srv/nfsroot/trusty
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cd /nfs
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chmod -R 777 /srv/nfsroot/trusty
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tar cvpjf trusty.tar.bz2 ./trusty
 
</syntaxhighlight>
 
</syntaxhighlight>
  
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- NOTES -
 
−
* The folder name should match your NetBoot settings. Folder name = a LABEL in the NetBoot config.
 
−
* The folder name should match a Linux (Debian like) distribution name
 
  
−
 
+
===Restoration===
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===Populate the content===
 
  
 
<syntaxhighlight lang="bash">
 
<syntaxhighlight lang="bash">
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cd /srv/nfsroot/trusty
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cd /nfs
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debootstrap trusty /srv/nfsroot/trusty
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tar -xvjf trusty.tar.bz2
 
</syntaxhighlight>
 
</syntaxhighlight>
  
 +
=PXE interactive menu=
  
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===Adjust default login/password===
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You can create interactive NetBoot menus, see:
 +
* [[PXE interactive menu - single level]]
 +
* [[PXE interactive menu - multi level]]
  
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You have to create / adjust the default user.
 
  
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To do so, we must "mount" the new system and perform operations on it.
 
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<syntaxhighlight lang="bash">
 
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# "mount" the system
 
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chroot /srv/nfsroot/trusty/
 
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# Add new user
 
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adduser <username>
 
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# Add user to sudoers group
 
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usermod -a -G sudo <username>
 
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# Exit chroot
 
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exit
 
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</syntaxhighlight>
 
  
  
 +
=Local server monitoring=
  
 +
Install the following services:
 +
* [[SNMP client]]
 +
* [[Zabbix agent setup]]
  
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=Custom NetBoot configuration=
 
  
  
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==Basic configuration==
 
  
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You can setup your own netboot configuration.
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=Other services=
  
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To do so, you can re-use one of the syslinux templates:
 
  
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<syntaxhighlight lang="bash">
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==File sharing==
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# Create folders
 
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mkdir /var/lib/tftpboot/custom
 
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mkdir /var/lib/tftpboot/custom/pxelinux.cfg
 
  
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# Create configuration files
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If you want to expose the NFS common folder as a file-share, you have to install and configure Samba. See: [[Samba server]]
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cp /usr/lib/syslinux/pxelinux.0 /var/lib/tftpboot/custom
 
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</syntaxhighlight>
 
  
  
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The ''pxelinux.cfg'' folder is mandatory. Inside you can provide:
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''Note''
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* configuration for a specific IP @ or hostname
 
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* configuration for a group
 
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* default configuration (required)
 
  
 +
Samba is actually better than NFS for the file-share. You should remove Common from /etc/exports and use a samba share instead.
  
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Create the default configuration file:
 
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<syntaxhighlight lang="bash">
 
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vim /var/lib/tftpboot/custom/pxelinux.cfg/default
 
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</syntaxhighlight>
 
  
  
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Put the following:
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==Management UI (webmin)==
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<syntaxhighlight lang="bash">
 
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# Ubuntu 14.04
 
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LABEL TRUSTY
 
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    kernel trusty/vmlinuz
 
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    initrd trusty/initrd.img
 
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    # Set NFS share as default root
 
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    append root=/dev/nfs nfsroot=172.16.50.2:/srv/nfsroot/trusty
 
  
 +
Since there is a lot of services to manage, it's always convenient to use an UI for it. Check [[Webmin]]
  
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# Prompt user for selection
 
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PROMPT 0
 
  
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TIMEOUT 30
 
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</syntaxhighlight>
 
  
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* Each LABEL is a specific configuration that will displayed on the NetBoot menu.
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==VPN server==
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* PROMPT 1 = enable user prompt so you can choose the configuration
 
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* TIMEOUT 30 = timeout (in seconds) before the default option is choosen
 
  
 +
See [[VPN]]
  
−
Note that I used a reference to "trusty/", that's a folder I need to create later on.
 
  
  
 +
==Apache2 server==
  
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==Create boot files==
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See [[Apache 2]]
  
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<syntaxhighlight lang="bash">
 
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mkdir /var/lib/tftpboot/custom/trusty
 
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# Copy current boot files
 
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cp /boot/vmlinuz-3.2.0-4-amd64 /var/lib/tftpboot/custom/trusty/
 
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cp /boot/initrd.img-3.2.0-4-amd64 /var/lib/tftpboot/custom/trusty/
 
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# Create symlinks
 
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ln -s /var/lib/tftpboot/custom/trusty/vmlinuz-3.2.0-4-amd64 /var/lib/tftpboot/custom/trusty/vmlinuz
 
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ln -s /var/lib/tftpboot/custom/trusty/initrd.img-3.2.0-4-amd64 /var/lib/tftpboot/custom/trusty/initrd.img
 
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</syntaxhighlight>
 
  
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Adjust the ''3.2.0-4'' kernel number to the version you are using
 
  
  
  
 +
=References=
  
 +
Ubuntu diskless how-to: https://help.ubuntu.com/community/DisklessUbuntuHowto
  
  
 +
Mind reference: http://mindref.blogspot.se/2011/03/debian-diskless.html
  
−
=References=
 
  
−
Ubuntu diskless how-to: https://help.ubuntu.com/community/DisklessUbuntuHowto
 
 
Super video tutorials:  
 
Super video tutorials:  
 
* https://www.youtube.com/watch?v=js9imsrqAMk
 
* https://www.youtube.com/watch?v=js9imsrqAMk
 
* http://www.stepladder-it.com/bivblog/14/ to /16/
 
* http://www.stepladder-it.com/bivblog/14/ to /16/
 +
* https://blog.dlasley.net/2013/01/pxe-server-ubuntu/
 +
 +
 +
Nice explanation of PXE process: http://www.linux.com/learn/docs/ldp/497-Diskless-root-NFS-HOWTO
 +
 +
* How to improved /etc/fstab: http://www.askapache.com/optimize/super-speed-secrets.html

Latest revision as of 15:37, 21 August 2014


Target folder tree (server side)

This is how we'll setup our files and folders: 

# TFTP root
/tftpboot/                                   

###############
# Network bootable image(s) using NFS technology
################       

#### Boot file            
/tftpboot/pxelinux.0                   # Initial boot file - only use to load the PXE NetBoot manager
/tftpboot/{menu.c32 || vesamenu.c32}   # PXE interactive menu managers (text or graphical)
/tftpboot/pxelinux.cfg/                # PXE configuration(s)
/tftpboot/pxelinux.cfg/default         # default PXE configuration

#### Kernel file

/tftpboot/images/      

# Debian 7.x [Wheezy] 
/tftpboot/images/wheezy/   
/tftpboot/images/wheezy/vmlinuz
/tftpboot/images/wheezy/initrd.img

# [X]Ubuntu 14.04 [Trusty] 
/tftpboot/images/trusty/  
/tftpboot/images/trusty/vmlinuz
/tftpboot/images/trusty/initrd.img


#### NFS 
# This is where the runnable will be. Each image will be in a dedicated folder.
/nfs/                    

# Debian 7.x [Wheezy] 
/nfs/wheezy/   

# Ubuntu 14.04 [Trusty] 
/nfs/trusty/


Client overview

Each client must have, at least, 4 Go of RAM.


4 GO RAM configuration

This is how we're gonna populate the client:

NetBoot client RAM overview - 4Go


As you can see, each client will have some space dedicated for swap + some RAMdisk to allow writing in /var, /tmp and /proc.


Configuration of a 4Go RAM disk:

  • No swap
  • Local TMPFS (read/write for /dev, /tmp, ...) : 1 Go
    • /tmp = 512 M
    • /var/tmp = 128 M
    • /var/log = 128 M
    • /var/run = 8 M
    • /var/lock = 8 M
    • /run/shm = 256 M
  • O.S (NFS read only) : all the rest ~ 2.8 Go
  • Common share (NFS read write) : Remote disk


2 Go

Due to budget restriction we might encounter some low memory machines with only 2 Go...


This is how we're gonna populate the client:

NetBoot client RAM overview - 2Go


In case of 2Go RAM then you have to use some tricks:

  • No swap
  • O.S (NFS read only) : ~ 1.2 Go
  • Common share (NFS read write) : Remote disk
  • Local TMPFS (read/write for /dev, /tmp, ...) : all the rest
    • /tmp = 372 M
    • /var/tmp = auto
    • /var/log = 128 M
    • /var/run = auto
    • /var/lock = auto
    • /run/shm = auto


How big is the client image ?

By default the deboostrap Ubuntu 14.04 LTS image is 239 Mo. With the applications we're gonna use that size will increase to about 1 or 1.3 Go depending if you copy (or not) the kernel sources. It may even take 1.6 Go if you're using XFCE frontend.


NFS client image

There are different way to setup a NFS client image.

The main ones are:

  • Manually
    • debootstrap
    • copying the install from your server
    • Manual install on a client, then, when the system is ready, copy everything to the NFS share
  • Using script and software like "Puppet" or "Chef"


Setup client distribution

You have to create one target for each distribution you want to serve: 

mkdir -p /nfs/trusty
mkdir -p /nfs/wheezy
mkdir -p /nfs/common


- NOTES -

  • The folder name should match your NetBoot settings. Folder name = a LABEL in the NetBoot config.
  • The folder name should match a Linux (Debian like) distribution name


Configure client distribution



Backup distribution

You can create an archive of your current distribution for later restore / re-use.


Compression

cd /nfs
tar cvpjf trusty.tar.bz2 ./trusty


Restoration

cd /nfs
tar -xvjf trusty.tar.bz2

PXE interactive menu

You can create interactive NetBoot menus, see:



Local server monitoring

Install the following services:



Other services

File sharing

If you want to expose the NFS common folder as a file-share, you have to install and configure Samba. See: Samba server


Note

Samba is actually better than NFS for the file-share. You should remove Common from /etc/exports and use a samba share instead.


Management UI (webmin)

Since there is a lot of services to manage, it's always convenient to use an UI for it. Check Webmin


VPN server

See VPN


Apache2 server

See Apache 2



References

Ubuntu diskless how-to: https://help.ubuntu.com/community/DisklessUbuntuHowto


Mind reference: http://mindref.blogspot.se/2011/03/debian-diskless.html


Super video tutorials:


Nice explanation of PXE process: http://www.linux.com/learn/docs/ldp/497-Diskless-root-NFS-HOWTO

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