fosdem - does your configuration code smell?

Does Your Configuration Code Smell?

TusharSharma

Smells

Code Smell

certain structures in the

code that suggest (sometimes

they scream for) the

possibility of refactoring.

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Jugaad

Jugaad is a colloquial Hindi word that can mean an

innovative fix or a simple work-around, used for solutions

that bend rules, or a resource that can be used as such, or

a person who can solve a complicated issue.

a work-around or hack

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Jugaad

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Jugaad

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Jugaad

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Jugaad

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Jugaad

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Smells are Jugaads in software

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Smells

Design Smells

Design smells are certain

structures in the design that

indicate violation of fundamental

design principles and negatively

impact design quality.

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Configuration Smells

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Infrastructure as Code (IaC)

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Puppet example

package { 'apache2':

require => Exec['apt-update'],

ensure => installed,

}

service { 'apache2':

ensure => running,

require => Package[apache2]

}

user { 'tushar':

ensure => present,

uid => '1000',

gid => '1000',

shell => '/bin/bash',

home => '/home/tushar'

}

Configuration management tools:

Ansible, Chef, CFEngine, Puppet 15

Software System

IaC and Traditional SE

Production code

Infrastructure, configuration

code, tools and services

Apply traditional software

engineering practices

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Configuration smells

Configuration smells are the characteristics of a

configuration program or script that violate the

recommended best practices and potentially

affect the programs quality in a negative way.

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Implementation configuration smells

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Implementation configuration smellsimport'classes/*'#TODO:fixdeprecatedstatementclassapp-studio(String$version=latest'){$primary_config_file='config'$source_config='config.source'if$version==44or$version==4.2or$version!=4.5or$version==4.9{case$::operatingsystem{'debian':{apt::source{'packages.dotdeb.org-repo.app':location=>'http://repo.app.com/dotdeb/',release=>$::lsbdistcodename,repos=>'all',include_src=>trueinclude_src=>true}}}

DeprecatedStatementUsage

IncompleteTask

DuplicateEntity

LongStatement

ComplexExpressionMissingDefaultCase

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Implementation configuration smellselsif$versionin['33','3.3']{}if$::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

}}

MissingConditional

ImproperQuoteUsageUnguardedVariable

ImproperAlignment

InvalidPropertyValueMisplacedAttribute

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Design configuration smells

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package.pp

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apache.pp

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Multifaceted Abstraction

Eachabstractionshouldbedesignedtospecifythepropertiesofasinglepieceofsoftware.

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init.pp

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Unnecessary Abstraction

Aclass,define,ormodulemustcontaindeclarationsorstatementsspecifyingthepropertiesofadesiredsystem.

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init.pp

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Imperative Abstraction

Anabstractioncontainingnumerousimperativestatementssuffersfromimperativeabstractionsmell.

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init.pp

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Missing Abstraction

Amodulesuffersfromthemissingabstractionsmellwhenresourcesandlanguageelementsaredeclaredandusedwithout

encapsulatingtheminanabstraction.

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web.pp server.pp

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Duplicate Block

Aduplicateblockofstatementsmorethanathresholdindicatesthatprobablyasuitableabstractiondefinitionismissing.

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init.pp

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Insufficient Modularisation

Anabstractionsuffersfromthissmellwhenitislargeorcomplexandthuscanbemodularizedfurther.

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Unstructured ModuleEachmoduleinaconfigurationrepositorymusthaveawell-

definedandconsistentmodulestructure.

RepoName

ManifestsModulesREADME

ApacheAdobe

fileslibmanifestsspectemplatestestsREADME

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Dense StructureThissmellariseswhenaconfigurationcoderepositoryhas

excessiveanddensedependencies.

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Weekend ModularityThissmellariseswhenamoduleexhibitshighcouplingand

lowcohesion.

Modularityratio(A)=Cohesion(A)

Coupling(A)

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Implications of smells

Thestrawthatbrokethecamel'sback41

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/Puppeteer42

Mining GitHub RepositoriesRepositories 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/ 43

Let us summarize

ME

LS

U

P

EER

II

P

T

U

I NM YI

IA A BNC

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Let us summarize

ME

LS

U

P

EER

II

P

T

U

IA NM YI

IA A BNC

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Let us summarize

SME

LS

U

P

EER

L II

P

T

U

IA NM YI

IA A BNC

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Let us summarize

SME

LS

U

P

P

EER

L II

P

T

U

IA NM YI

IT A A BNC

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Thank you!!

Courtesy:spikedmath.com

Tushar [email protected]

@Sharma__Tushar

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