Does your configuration code smell?

by Tushar Sharma
DevOps Pro Vilnius 2016

Transcript

1. Does Your Configuration Code Smell? Tushar Sharma
2. “Smells” Code Smell …certain structures in the code that suggest (sometimes they scream for) the possibility of refactoring.
4. “Smells” Design Smells “Design smells are certain structures in the design that indicate violation of fundamental design principles and negatively impact design quality.”
5. “Smells” Configuration Smells
6. “Infrastructure as Code” (IaC)
7. Puppet example package { 'apache2': require => Exec['apt-update'], ensure => installed, } service { 'apache2': ensure => running, } user { 'tushar': ensure => present, uid => '1000', gid => '1000', shell => '/bin/bash', home => '/home/tushar' } Configuration management tools: Ansible, Chef, CFEngine, Puppet
8. Software System IaC and Traditional SE Production code Infrastructure, configuration code, tools and services Apply traditional software engineering practices
9. Configuration smells “Configuration smells are the characteristics of a configuration program or script that violate the recommended best practices and potentially affect the program’s quality in a negative way.”
10. Implementation configuration smells
11. Implementation configuration smells import 'classes/*' # TODO: fix deprecated statement class app-studio (String $version = ‘latest') { $primary_config_file = 'config' $source_config = 'config.source' if $version == ’44’ or $version == ‘4.2’ or $version != ‘4.5’ or $version == ‘4.9’{ case $::operatingsystem { 'debian': { apt::source { 'packages.dotdeb.org-repo.app': location => 'http://repo.app.com/dotdeb/', release => $::lsbdistcodename, repos => 'all', include_src => true include_src => true } } Deprecated Statement Usage
12. Implementation configuration smells import 'classes/*' # TODO: fix deprecated statement class app-studio (String $version = ‘latest') { $primary_config_file = 'config' $source_config = 'config.source' if $version == ’44’ or $version == ‘4.2’ or $version != ‘4.5’ or $version == ‘4.9’{ case $::operatingsystem { 'debian': { apt::source { 'packages.dotdeb.org-repo.app': location => 'http://repo.app.com/dotdeb/', release => $::lsbdistcodename, repos => 'all', include_src => true include_src => true } } Incomplete Task
13. Implementation configuration smells import 'classes/*' # TODO: fix deprecated statement class app-studio (String $version = ‘latest') { $primary_config_file = 'config' $source_config = 'config.source' if $version == ’44’ or $version == ‘4.2’ or $version != ‘4.5’ or $version == ‘4.9’{ case $::operatingsystem { 'debian': { apt::source { 'packages.dotdeb.org-repo.app': location => 'http://repo.app.com/dotdeb/', release => $::lsbdistcodename, repos => 'all', include_src => true include_src => true } } Long Statement Complex Expression
14. Implementation configuration smells import 'classes/*' # TODO: fix deprecated statement class app-studio (String $version = ‘latest') { $primary_config_file = 'config' $source_config = 'config.source' if $version == ’44’ or $version == ‘4.2’ or $version != ‘4.5’ or $version == ‘4.9’{ case $::operatingsystem { 'debian': { apt::source { 'packages.dotdeb.org-repo.app': location => 'http://repo.app.com/dotdeb/', release => $::lsbdistcodename, repos => 'all', include_src => true include_src => true } } Missing Default Case
15. Implementation configuration smells import 'classes/*' # TODO: fix deprecated statement class app-studio (String $version = ‘latest') { $primary_config_file = 'config' $source_config = 'config.source' if $version == ’44’ or $version == ‘4.2’ or $version != ‘4.5’ or $version == ‘4.9’{ case $::operatingsystem { 'debian': { apt::source { 'packages.dotdeb.org-repo.app': location => 'http://repo.app.com/dotdeb/', release => $::lsbdistcodename, repos => 'all', include_src => true include_src => true } } Duplicate Entity
16. Implementation configuration smells elsif $version in ['33', '3.3'] { } if $::kernelversion =~ /^(2.2)/ { $appversion = '3.5' } elsif $::kernelversion =~ /^(2.1)/ { exec {"download_app_studio": command => "wget $url", timeout => 0, } } $version = '3.4' ? {undef => $primary_config_file, default => $source_config} file { "/root/.app": mode => '644', ensure => present } } Missing Conditional
17. Implementation configuration smells elsif $version in ['33', '3.3'] { } if $::kernelversion =~ /^(2.2)/ { $appversion = '3.5' } elsif $::kernelversion =~ /^(2.1)/ { exec {"download_app_studio": command => "wget $url", timeout => 0, } } $version = '3.4' ? {undef => $primary_config_file, default => $source_config} file { "/root/.app": mode => '644', ensure => present } } Improper Quote Usage
18. Implementation configuration smells elsif $version in ['33', '3.3'] { } if $::kernelversion =~ /^(2.2)/ { $appversion = '3.5' } elsif $::kernelversion =~ /^(2.1)/ { exec {"download_app_studio": command => "wget $url", timeout => 0, } } $version = '3.4' ? {undef => $primary_config_file, default => $source_config} file { "/root/.app": mode => '644', ensure => present } } Unguarded Variable
19. Implementation configuration smells elsif $version in ['33', '3.3'] { } if $::kernelversion =~ /^(2.2)/ { $appversion = '3.5' } elsif $::kernelversion =~ /^(2.1)/ { exec {"download_app_studio": command => "wget $url", timeout => 0, } } $version = '3.4' ? {undef => $primary_config_file, default => $source_config} file { "/root/.app": mode => '644', ensure => present } } Improper Alignment
20. Implementation configuration smells elsif $version in ['33', '3.3'] { } if $::kernelversion =~ /^(2.2)/ { $appversion = '3.5' } elsif $::kernelversion =~ /^(2.1)/ { exec {"download_app_studio": command => "wget $url", timeout => 0, } } $version = '3.4' ? {undef => $primary_config_file, default => $source_config} file { "/root/.app": mode => '644', ensure => present } } Invalid Property Value
21. Implementation configuration smells elsif $version in ['33', '3.3'] { } if $::kernelversion =~ /^(2.2)/ { $appversion = '3.5' } elsif $::kernelversion =~ /^(2.1)/ { exec {"download_app_studio": command => "wget $url", timeout => 0, } } $version = '3.4' ? {undef => $primary_config_file, default => $source_config} file { "/root/.app": mode => '644', ensure => present } } Misplaced Attribute
22. Design configuration smells
23. class package::web { … } class package::mail { … } class package::environment { … } class package::user { … } package.pp
24. class apache { package { 'apache2': … } service { 'apache2': … } service { 'mysql': … } package { 'php5': … } file { ‘/etc/apache2/ports.conf': … } user { ‘mitchell': … } } apache.pp
25. Multifaceted Abstraction • 
 Each abstraction should be designed to specify the properties of a single piece of software.
26. class web { } init.pp
27. Unnecessary Abstraction A class, ‘define’, or module must contain declarations or statements specifying the properties of a desired system.
28. class web { exec { ‘hadoop-yarn’: … } exec { ‘apache-util-set’: … } exec { ‘smail-invoke’: … } exec { ‘postfix-set’: … } } init.pp
29. Imperative Abstraction An abstraction containing numerous imperative statements suffers from imperative abstraction smell.
30. package { 'apache2': … } service { 'apache2': … } service { 'mysql': … } package { 'php5': … } file { ‘/etc/apache2/ports.conf': … } user { ‘mitchell': … } init.pp
31. Missing Abstraction A module suffers from the missing abstraction smell when resources and language elements are declared and used without encapsulating them in an abstraction.
32. class apache { package { 'apache2': … } service { 'apache2': … } file { ‘/etc/apache2/ports.conf': … } … } web.pp class apache { package { 'apache2': … } service { 'apache2': … } file { ‘/etc/apache2/ports.conf': … } … } server.pp
33. Duplicate Block A duplicate block of statements more than a threshold indicates that probably a suitable abstraction definition is missing.
34. package { 'apache2': … } service { 'apache2': … } service { 'mysql': … } package { 'php5': … } file { ‘/etc/apache2/ports.conf': … } user { ‘mitchell': … } package { 'apache2': … } service { 'apache2': … } service { 'mysql': … } package { 'php5': … } file { ‘/etc/apache2/ports.conf': … } user { ‘mitchell': … } package { 'apache2': … } service { 'apache2': … } service { 'mysql': … } package { 'php5': … } file { ‘/etc/apache2/ports.conf': … } user { ‘mitchell': … } init.pp
35. Insufficient Modularisation An abstraction suffers from this smell when it is large or complex and thus can be modularized further.
37. Unstructured Module Each module in a configuration repository must have a well-defined and consistent module structure. RepoName Manifests Modules README … Apache Adobe … files lib manifests spec templates tests README …
39. Dense Structure This smell arises when a configuration code repository has excessive and dense dependencies.
41. Weekend Modularity This smell arises when a module exhibits high coupling and low cohesion. Modularity ratio (A) = Cohesion(A) Coupling(A)
42. Implications of smells The straw that broke the camel's back
43. Detecting configuration smells Implementation configuration smells • Puppet-lint [1] • Additional custom rules in Puppeteer Design configuration smells • Puppeteer [2] — an open source tool 1. http://puppet-lint.com/ 2. https://github.com/tushartushar/Puppeteer
44. Mining GitHub Repositories Repositories 4,621 Puppet files 142,662 Class declarations 132,323 Define declarations 39,263 File resources 117,286 Package resources 49,841 Service resources 18,737 Exec declarations 43,468 Lines of code (Puppet only) 8,948,611 http://www.tusharma.in/research/does-your-configuration-code-smell-msr-2016/
45. Let us summarize M E L S U P E E R I I P T U I N M Y I I A A B N C
46. Let us summarize M E L S U P E E R I I P T U I A N M Y I I A A B N C
47. Let us summarize S M E L S U P E E R L I I P T U I A N M Y I I A A B N C
48. Let us summarize S M E L S U P P E E R L I I P T U I A N M Y I I T A A B N C
49. Thank you!! Courtesy: spikedmath.com Tushar Sharma tusharsharma@ieee.org @Sharma__Tushar