augeas - a configuration api

8/12/2019 Augeas - A Configuration API

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Augeas a configuration APIDavid Lutterkort

Red Hat, Inc.


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Configuration Management

Sitewide configuration

Local configuration


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Editing of Configuration Data

(1) Keyhole a roache!

(") #reenfield a roache!

($) %e& lating


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Missing pieces

Handle configuration data unifor&ly

'olicy delegation

Re&ota le *'I

*ugea! lay! the foundation for addre!!ing the!e


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Design Goals

(1) Deal with configuration data in it! current lace


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Design Goals

(") + o!e a !tract tree view of configuration data


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Design Goals

($) 're!erve -uni& ortant detail


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Design Goals

(/) De!cri e new file for&at! ea!ily and !afely


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Design Goals

(0) Language neutral i& le&entation


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Design Goals

( ) 2ocu! on configuration editing


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The Augeas Tree


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The Augeas Tree


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The public Augeas APIS&all nu& er of call! to &odify tree

init/close get/set value a!!ociated with a node match node! with ath e re!!ion insert efore after e i!ting node

rm !u tree save tree ack to file


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The public Augeas API

3 *'I ( libaugeas.so )

3o&&and line tool augtool

Language inding! for 'ython, Ru y, 4ca&l, ...


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E ample! /etc/hosts2or&at5# ipaddr canonical ( alias)* \n

127.0.0.1 localhost localhost.localdomain host.domain

Sche&a5/files/etc/hosts 1 / ipaddr 127.0.0.1 canonical localhost alias localhost.localdomain alias host.domain


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E ample! /etc/hostsaugtool! set /files/etc/hosts/1/alias"2 m$host.domain

Sche&a5/files/etc/hosts 1/

ipaddr 127.0.0.1 canonical localhost alias localhost.localdomain alias m$host.domain


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E ample! /etc/hostsaugtool! ins alias after /files/etc/hosts/1/alias"1

Sche&a5/files/etc/hosts 1/

ipaddr 127.0.0.1 canonical localhost alias localhost.localdomain alias

alias m$host.domain


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E ample! /etc/hostsaugtool! set /files/etc/hosts/1/alias"2 m$host

Sche&a5/files/etc/hosts 1/ ipaddr 127.0.0.1 canonical localhost alias localhost.localdomain alias m$host alias m$host.domain


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E ample! /etc/hostsaugtool! sa%e

6ew /etc/hosts 5# ipaddr canonical ( alias)* \n

127.0.0.1 localhost localhost.localdomain m$host m$host.domain


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E ample! yu& configuration%ree! underneath /files/etc/$um.conf /files/etc/$um.repos.d/some.repo&chema /section/'e$ %alue

Switch 2edora re o to internal &irror5 /files/etc/$um.repos.d/fedora.repoaugtool! rm /fedora/mirrorlist

augtool! set /fedora/baseurl mirror1augtool! ins baseurl after /fedora/baseurlaugtool! set /fedora/baseurl"last() mirror2


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Overall architecture


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"chema descriptionmodule um autoload +fm

let lns ...

let filter (incl ,/etc/$um.conf,) . (incl ,/etc/$um.repos.d/*,) . -til.stde+cl

let +fm transform lns filter


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let lns ...




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let lns ...




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let lns ...




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#enses

3oncrete 7iew * !tract 7iew

8idirectional rogra&&ing

3oncrete 9 * !tract : * !tract 9 3oncrete

Har&ony (; 'enn) doe! it for tree!8oo&erang (; 'enn) doe! it for !tring!%heoretical groundwork y 8. 'ierce, 6. 2o!ter et.al.


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#enses for Augeas

String %ree

get 5 String 9 %ree

put 5 %ree String 9 String


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#ens #a$s

%he get and put of every len! &u!t fulfill5

put (get c) c c

get (put a c) a

3a ture intuitive notion! of -&ini&al edit! 3on!traint! enforced y ty echecker


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#ens primitives%ree la el!

'e$ re label str se str

%ree value! store re

4&it fro& tree del re str


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#ens combinatorsl1 . l2 5 Len! concatenation

l1 l2 5 Len! union

l* l 5 Len! iteration

" l 5 Su tree co& inator


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#ens development8uild u len!e! fro& !&all art!Reu!e co&&on con!truct!

3o&&ent goe! fro& < to end of line;nit te!t facility in *ugea! language

Run get direction Run get direction, &odify tree, run ut direction 3o& are to fi ed value *!!ert e ce tion 'rint re!ult


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#ens development

'roce!! 'e$ %alue3


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#ens development

'roce!! 'e$ %alue3

let e del 3 3


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#ens development

'roce!! 'e$ %alue3

let e del 3 3let lns " 'e$ /"a45 / . e . store /. /


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#ens development

'roce!! 'e$ %alue3


d l


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#ens development

'roce!! 'e$ %alue3



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# d l t


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#ens development

'roce!! 'e$ %alue3


test lns get foo bar3 foo3 bar3 8

# d l t


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#ens development

'roce!! 'e$ %alue3


test lns get foo2 bar13 *

#ens development


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#ens development

'roce!! 'e$ %alue3

let e del 3 3let lns "'e$ /"a45 / . e . store /. /

test lns put foo bar3after set foo3 ba53

6

#ens development


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#ens development

'roce!! 'e$ %alue3



6

#ens development


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#ens development

'roce!! 'e$ %alue3



foo ba53

#ens development


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#ens development

'roce!! 'e$ %alue3

let e del /" \t " \t / 3let lns " 'e$ /"a45 / . e . store /. /

#ens development


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#ens development

'roce!! 'e$ %alue3

let e del /" \t " \t / 3let lns " 'e$ /"a45 / . e . store /. /

#ens development


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#ens development

'roce!! 'e$ %alue3

let e del /" \t " \t / 3let lns " 'e$ /"a45 / . e . store /"a45 /

test lns put foo \t bar3 after set foo3 ba53 foo \t ba53

Arra%s using seq


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Arra%s using seqhosts/ 1 / ipaddr canonical alias alias 2 / ipaddr canonical alias

Arra%s using identical labels


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Arra%s using identical labelshosts/ 1/ ipaddr canonical alias alias 2/ ipaddr canonical alias


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&andling comments


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g

let comment " del /#.*\n/ #\n3

let lns (record comment)*

The lens t%pechec'er


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p+ach len! ha! a!!ociated ctype and atype

Regular language!

3heck! during len! con!truction del re str 5 str &u!t &atch re l1 . l2 5 una& iguou!ly ! litta le l1 | l2 5 di!=oint regular language!

libfa for finite auto&ata co& utation!

Re!trict! *ugea! to regular file for&at!

"upported file formats


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pp

etc ho!t! etc initta yu& config etc f!ta

etc alia!e! etc !!h !!hd>config

!hell var! in etc !y!config ifcfg?@

gru .conf inetd.d

a&.d v!ft d.conf your contri ution here

(hat about httpd.conf )


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Ao!tly tediou! oiler late+ ce t5

... 9:f;odule mod


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D u! !ervice acked y *ugea!

:'olicyKit &echani!& for authentication

B

Local configuration !ervice;I inde endent

2ile for&at inde endent2ine grained er&i!!ioning

Harald Hoyer ha! rototy e for s$stem4config4boot

"upported platforms


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Red Hat Linu flavor! 2edora, RH+L, 3ent4S, ...

4ther Linu flavor! De ian

2ree8SD4S C ort on the way

Aini&al de endencie!*nything with a #6; li c (or e uivalent gnuli !u ort)

More information


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'ro=ect we !ite htt 5 augea!.net Read the -Euick %our fir!t

Aailing li!t augea!?develFredhat.co&IR3

augeas - a configuration api

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