Debian Administration

Automatic host installation using Viper

The purpose of this article is to give you a straight-forward, Debian-friendly way of installing and configuring Viper, a system for completely automated installation and configuration of Debian GNU based systems.

Introduction

Viper is a system for completely automated installation and configuration of Debian GNU based systems.

It is a newly developed system that had the first public release in August 2009. This article should serve as an early introduction, focusing on the results. For more on the underlying logic and in-depth treatment of various topics, refer to official Viper documentation.

Viper uses a modern approach (debian-installer, Puppet etc.), works with existing Debian packages, and does not require any custom patching of either install media, client or server.

The basis of the whole system is a LDAP server, containing all configuration data.
If you are not familiar with LDAP and related terminology, glance over my other article, OpenLDAP installation on Debian, found here or here.

LDAP has the potential to be enormously successful in configuration management, but its flat data structure, absence of any kind of dynamic behavior, and heaps of duplicated data make it a mediocre tool.
To build on LDAP's great strengths while solving its deficiencies, a custom OpenLDAP backend has been implemented.

The setup explained here will get you to a point that you can perform an automatic installation of a Debian host. The configuration part is done using Puppet, but is not covered here; expect it soon as another article on debian-administration.org and the official website.

Viper download and setup

The instructions shown should quickly set you up with a Viper install server, using fully-working example configuration shipped with Viper, that you can test with and without actual client hosts. Then, after that, you should be able to start with writing your own site and hosts configuration.

It would be best if you can install Viper on a clean system without important data. However, the install script will only modify OpenLDAP, DHCP and Puppet server config so you should be able to install it on any system that does not already use one of those.

That said, let's move onto the setup.

Download Viper:

apt-get install git-core
mkdir -p /etc/ldap
cd /etc/ldap
git clone git://github.com/docelic/Viper.git viper 

Now, to set things up, you should just have to run scripts/viper-setup.sh. It should do everything automatically.

However, for the first time, I suggest you read the script (it contains comments) and execute commands manually.

Before running the script, you should do just one thing related to the DHCP server -- you should create a network interface with IP address 10.0.1.1, to fit in the example subnet used by our default config. Then, you can run the install script with the name of the physical interface. Here's the session transcript:

ifconfig eth0:1 inet 10.0.1.1 netmask 255.255.255.0

sh scripts/viper-setup.sh eth0

To configure eth0:1 on every boot, add it to /etc/network/interfaces with a stanza like this:

allow-hotplug eth0:1
iface eth0:1 inet static
  address 10.0.1.1
  netmask 255.255.255.0

Net::LDAP::FilterMatch fix

Net::LDAP's FilterMatch module contains a bug that you have to patch manually, at least until it is fixed in the official distribution.

The patch file is included in downloaded files, so you just need to execute:

patch -p0 < support/FilterMatch.pm.patch

And then re-start slapd with invoke-rc.d slapd restart.

Testing the installation

The above simple procedure should have set you up with a working Viper-enabled LDAP server, DHCP server, and default configuration data you can query from the command line.

Tests you can run:

With ldapsearch

ldapsearch -x -b ou=dhcp
ldapsearch -x -b ou=defaults
ldapsearch -x -b ou=clients

ldapsearch -x -b cn=h2,ou=hosts,o=c1.com,ou=clients

ldapsearch -x -b cn=popularity-contest/participate,ou=hosts,ou=defaults
ldapsearch -x -b cn=debian-installer/locale,cn=h2,ou=hosts,o=c1.com,ou=clients
ldapsearch -x -b cn=ntp/servers,cn=h2,ou=hosts,o=c1.com,ou=clients

Test results

Ldapsearch query for cn=h2,ou=hosts,o=c1.com,ou=clients is a pretty good way of determining if everything is working alright. Here's how the output from the command should look like:

$ ldapsearch -x -b cn=h2,ou=hosts,o=c1.com,ou=clients

# extended LDIF
#
# LDAPv3
# base  with scope subtree
# filter: (objectclass=*)
# requesting: ALL
#

# h2, hosts, c1.com, clients
dn: cn=h2,ou=hosts,o=c1.com,ou=clients
objectClass: top
objectClass: device
objectClass: dhcpHost
objectClass: ipHost
objectClass: ieee802Device
objectClass: puppetClient
cn: h2
ipHostNumber: 10.0.1.8
macAddress: 00:11:6b:34:ae:8d
puppetclass: test
puppetclass: ntp::server
dhcpHWAddress: ethernet 00:11:6b:34:ae:8d
dhcpOption: host-name "h2"
dhcpOption: routers 10.0.1.1
dhcpOption: domain-name-servers 192.168.1.254
dhcpOption: nis-domain "c1.com"
dhcpOption: domain-name "c1.com"
dhcpOption: subnet-mask 255.255.255.0
dhcpOption: broadcast-address 10.0.1.255
dhcpStatements: fixed-address 10.0.1.8
hostName: h2
ipNetmaskNumber: 255.255.255.0
clientName: c1.com
ipNetworkNumber: 10.0.1.0
ipBroadcastNumber: 10.0.1.255
domainName: c1.com

# search result
search: 2
result: 0 Success

# numResponses: 2
# numEntries: 1

With scripts/node_data

perl scripts/node_data h2.c1.com

With scripts/preseed

QUERY_STRING=ip=10.0.1.8 perl scripts/preseed

Installing a client host

Adjust defaults and host's macAddress

After you've got the Viper server running and the tests are successful, you can attempt installing a host.

To do so, go to /etc/ldap/viper/ldifs/ and edit two LDIF files, 0-defaults.ldif and c1.com.ldif.

In the defaults file, you should go over all the values (search for occurences of "value:") and adjust them if any need change in your setup.

In the c1.com.ldif file, you should basically just modify the macAddress of host h1, and set it to the MAC address of the host you want to install.

Then, you should run 'make' in the current directory to load all .ldif files into LDAP.

Set up Apache to handle requests for preseed.cgi

Apache setup will already be done correctly if your cgi-bin directory is the standard /usr/lib/cgi-bin/ and accessible through default vhost at location /cgi-bin/. If not, adjust accordingly.

On the client host

To install the client, boot from official boot media, and simply select Advanced --> Automatic installation.

If your host has multiple network interfaces, you might also add interface=ethX on the boot line, or answer that question manually when asked by the installer. (The d-i installer should supposedly auto-detect the interface, but it seems this isn't working 100% well yet).

The results

The client host should install automatically and reboot into the newly installed system.

Comments, questions and requests for clarification welcome here as the article followup, or on the Viper mailing list.

For more about Viper and further documentation, refer to Viper resources:

Viper homepage
Viper mailing list
Viper @ GitHub

Davor Ocelic
http://www.spinlocksolutions.com/

Copyright (C) 2007,2008 Davor Ocelic, <docelic@spinlocksolutions.com>
Spinlock Solutions, http://www.spinlocksolutions.com/

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