Automated Installation and System Configuration with AutoYaST

Configuration management system

In order to create a control file or a certain class of control files, one can use a YaST module.

Installation sources

There are quite a number of different installation sources and control file sources. In the simplest scenario, one can use the standard SuSE Linux Enterprise Server CDs as installation sources and provide the control file on a DOS formatted floppy disk. In a more advanced situation, but without network connectivity, YaST can create a ISO image file wich contains all packages and the control file. Using the network, installation can be done using NFS (Network File System). Then the control file can be provided in different places:

Booting can be done via network (etherboot/PXE) or via CDROM.

Hardware detection

During autoinstall, the same convenient hardware detection is used as for interactive install using YaST. This is archieved through the complete integration of AutoYaST into the installation and configuration system.

System Customization

Most of the system customization is done in the second stage of the installation. YaST provides most of the important resources needed to bring up a system to a usable, general state. However, you may have other requirements for the installed system. If the required customizations can't be done using YaST resources, then the post-install scripts can be used to accomplish this task. You can define an unlimited number of custom scripts in the control file either by editing the control file or by using the configuration system.

Rule Based Installation

Rules offer the possibility to configure a system depending on system attributes by merging multiple control file during installation. The rules based installation is controlled by a rules file.

The rules file is an XML based file that contains rules for each group of systems (or single systems) that you want to automatically install. A set of rules distinguish a group of systems based on one or more system attributes, after passing all rules, it links each group of rules to a profile. Both the rules file and the profiles must be located in a pre-defined and accessible location.

If more than one rule apply, the final profile for each group is generated on the fly using a merge script. The merging process is based on the order of the rules and later rules override configuration data in earlier rules.

The use of a rules file is optional. If the rules file is not found, system installation proceeds in the classic way by just using the supplied profile or by searching for the profile depending on the MAC or the IP address of the system.

The following simple example illustrates how the rules file is used to retrieve the configuration for a client with known hardware.

<?xml version="1.0"?>
<!DOCTYPE autoinstall SYSTEM "/usr/share/autoinstall/dtd/rules.dtd">
<autoinstall xmlns="http://www.suse.com/1.0/yast2ns" xmlns:config="http://www.suse.com/1.0/configns">
  <rules config:type="list">
    <rule>
       <disksize>
            <match>/dev/hdc 1000</match>
            <match_type>greater</match_type>
       </disksize>
       <result>
            <profile>machine1.xml</profile>
            <continue config:type="boolean">false</continue>
        </result>
    </rule>
    <rule>
       <disksize>
            <match>/dev/hda 1000</match>
            <match_type>greater</match_type>
       </disksize>
       <result>
            <profile>machine2.xml</profile>
            <continue config:type="boolean">false</continue>
        </result>
    </rule>
  </rules>
</autoinstall>

        

The last example defines 2 rules and provides a different profile for every rule. The rule used in this case is disksize. After parsing the rules file, YaST2 attempts to match the system being installed to the rules in the rules.xml file in order: first rule through the last rule. A rule match occurs when the system being installed matches all of the system attributes defined in the rule. As soon as a system matches a rule, the result resource is added to the stack of profiles AutoYaST will be using to create the final profile. The continue property tells AutoYaST if it should continue with other rules or not.

If the first rule does not match, next rule in the list is examined until a match is found.

Using the disksize attribute, you can provide different configurations for different hard drives with different size. First rule checks if the device /dev/hdc is available and if it is greater than 1 GB in size using the match property.

Introduction

The control file is in most cases a configuration description for a single system. It consists of sets of resources with properties including support for complex structures representations such as lists, records, trees and large embedded or referenced objects.

Format

The XML configuration format provides a consistent file structure, which is easier to learn and remember when attempting to configure a new system.

Using XML, you can eliminate (nearly) all of the configuration file parsing and error handling - an external XML parser can do that instead - (especially if it is a validating parser). To make sure the control file is well-formatted and that the syntax is valid, you can run the control file through a validating parser before it is actually used for automatic installation. This is especially required if you prefer to edit the profile manually.

The following example shows a control file in XML format:

<?xml version="1.0"?>
<!DOCTYPE profile SYSTEM
 "/usr/share/autoinstall/dtd/profile.dtd">
 <profile
 xmlns="http://www.suse.com/1.0/yast2ns"
 xmlns:cfg="http://www.suse.com/1.0/configns">
 <install>
   <partitioning  config:type="list">
      <drive>
         <device>/dev/hda</device>
         <partition>
            <filesystem>ext2</filesystem>
            <size>520Mb</size>
            <mount>/</mount>
         </partition>
         <partition>
            <filesystem>reiser</filesystem>
            <size>1200Mb</size>
            <mount>/data</mount>
         </partition>
      </drive>
   </partitioning>
 </install>
 <configure>
   <scripts>
    <pre-scripts>
     <script>
        <interpreter>shell</interpreter>
    <filename>start.sh</filename>
         <source>

            <![CDATA[
        #!/bin/sh
        echo "Starting installation"
        exit 0
           ]]>

         </source>
     </script>
    </pre-scripts>
   </scripts>
 </configure>
</profile>