Master- /Diplomstudium:Software Engineering - Internet Computing
Master's Thesis Presentation
Configuration Management with Libelektra
Bernhard Denner
Technische Universität WienFaculty of Informatics
Institute of Computer Languages Supervisor: Ao.Univ.-Prof.Dipl.-Ing. Dr.techn. Franz Puntigam
Co-Supervisor: Univ.Ass.Dipl.-Ing. Dr.techn. Markus Raab
Introduction and Motivation
Configuration Management (CM) Tools - Automatic and reproducible management of computer systems - Desired system state defined by code
Configuration Files - Plain text - Different formats: INI, XML, JSON, custom
Approach
Results
ERB
KDB
500 1000 1500 2000 2500 3000 3500
RQ: How does our approach perform against existing Puppet file modification concepts?
Case Study: - Is our solution ready for real-world scenarios?
User Study: - Does our solution increase the usabiltiy and maintainability? - Intra-subject SW-experiment - 4 Puppet programming tasks in up to 3 variants - Measure task duration times - Subjective impressions of participants (voting from 1 - 5)
Combine Puppet + Libelektra - Puppet as frontend to express needs - Libelektra as backend to modify configuration files
Puppet extension puppet-libelektra - Treat configuration settings as first class citizen - One language construct to define configuration settings for different configuration file formats - Brings all features of Libelektra to Puppet
puppet-libelektra extends Puppet DSL by two new types: - kdbkey defines a single configuration setting, with optional metadata (validation properties...) - kdbmount describes how Libelektra should integrate a configuration file, if not already done by the application
Problem - How to handle configuration file changes in a uniform way? - Abstraction for configuration settings? - Syntax and semantic awareness?
Libelektra: configuration framework - Configuration settings as key-value pairs - Hierarchical shared key space - Plugin architecture, extensible
kdbmount { 'system/sw/myapp': file => '/etc/myapp/config.ini', plugins => ['ini', 'range', 'enum']}
kdbkey { 'system/sw/myapp/instances': ensure => present, value => ${instance_count}, comments => 'configures the number ...', check => { 'range' => '1-10' }}
Methods
Kontakt: [email protected], [email protected], https://libelektra.org
Case Studypuppet-libelektra was used to manage a continuous integration and Web-hosting system
User StudySW-experiment with 14 subjects, all students without Puppet experience - significant shorter development times for creating or updating configuration files compared to other general purpose strategies - almost at the same level with format specific strategies - no productivity improvement in code maintenance
general purpose strategies KDB ERB AUG
... puppet-libelektra
... Ruby ERB template engine
... Augeas
format specific: HOST INI
... edit /etc/hosts files
... edit INI files
ERBHOST
INIAUGKDB
1 2 3 4 5
Create new configuration files from scratch
Maintenance of existing Puppet code
Subjective Usability Ratings
Task duration time (seconds)
Usability rating: 1 (very good) ... 5 (very bad)
ERB
KDB
1000 2000 3000 4000
Update configuration files
HOST/INIAUGKDB
1000 2000 3000 4000
Backend SystemMain System
Apache Web Server
libelektra.orgwebpage
sub-domainredirects
Jenkinsreverse proxy
JenkinsBuild Server
Docker
Build slavesBuild slavesBuild Slave
Build System
Build slaves
Build System
Build slaves
Build System
Build Slave
Snippet-sharingREST Backend
Build Slave
Puppet Agent
Module
puppet-libelektra
libelektra-core
system/sw/myapp system/network/hosts
hostsini
/etc/myapp/config.ini
[general]instances = 5domain = example.com
[logging]log_level = info
/etc/hosts
127.0.0.1 localhost
192.168.1.3 bbnode1 node1192.168.1.4 bbnode2 node2192.168.1.10 bbclient1 client1
Puppet - Open source CM-tool - Declariative domain specific language (DSL) - Modify configuration files in different ways
CM-ToolAgent
CM-ToolAgent
CM-ToolAgent
package { 'firefox': ensure => installed}
file { '/etc/resolv.conf': ensure => file, content => "search ${domain}"}
abstraction
high
low
enforce
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