xenial (7) elektra-plugins.7.gz

NAME

       elektra-plugins - plugins overview

       Plugins can be mounted into the KDB and can access or manipulate the KeySet on every access.

       Multiple  plugins  can  be mounted into the key data base elektra-glossary.md. On every access to the key
       data base they are executed and thus can change the functionality.Elektra already has  a  wide  range  of
       different  plugins.  The  plugin  folders should contain a README.md with further information. (Or follow
       links below.) The plugins are:

       For background information see elektra-plugins-framework(7) elektra-plugins-framework.md.

C-Interface

       All plugins implement the same interface:

       •   kdbOpen() calls elektraPluginOpen() of every plugin to let them do their initialisation.

       •   kdbGet() requests elektraPluginGet() of every plugin in the queried backends to return a key set.

       •   kdbSet() usually calls elektraPluginSet() of every plugin  in  the  queried  backends  to  store  the
           configuration.

       •   kdbSet()  also  calls  elektraPluginError()  for  every  plugin  when  an  error  happens. Because of
           elektraPluginError(), plugins are guaranteed to have their chance for necessary cleanups.

       •   kdbClose() makes sure that plugins can finally free their own resources in elektraPluginClose().

KDB-Interface

       •   To list all plugins use kdb-list(1) kdb-list.md.

       •   To check a plugin use kdb-check(1) kdb-check.md.

       •   For information on a plugin use kdb-info(1) kdb-info.md.

       •   For mount plugin(s) use kdb-mount(1) kdb-mount.md.

See also

       For an easy introduction, see this tutorial how to write a storage plugin /doc/tutorials/plugins.md.  For
       more  background  information  of  the  plugin  framework,  continue  here /doc/help/plugin-framework.md.
       Otherwise,        you         can         visit         the         the         API         documentation
       http://doc.libelektra.org/api/current/html/group__plugin.html.

Resolver

       Before  configuration  is  actually  written, the file name needs to be determined (will be automatically
       added by kdb mount):

       •   resolver resolver/ uses POSIX APIs to handle conflicts gracefully

       •   wresolver wresolver/ minimalistic resolver for non-POSIX systems

       •   noresolver noresolver/ does not resolve, but can act as one

       and afterwards the configuration file must be synced with harddisc  (recommended  to  add  at  every  kdb
       mount):

       •   sync sync/ uses POSIX APIs to sync configuration file with harddisc

Storage

       Are responsible for reading writing the configuration to configuration files.

       Read and write everything a KeySet might contain:

       •   dump dump/ makes a dump of a KeySet in an Elektra-specific format

       Read (and write) standard config files of /etc:

       •   augeas augeas/ parses and generates many different configuration files using the augeas library

       •   hosts hosts/ read/write hosts files

       •   line line/ reads any file line by line

       Using semi-structured data for config files:

       •   tcl tcl/-like config files (including meta data).

       •   ni           ni/           parses           INI          files          based          on          ni
           https://github.com/chazomaticus/bohr/blob/master/include/bohr/ni.h.

       •   ini ini/ parses INI files based on inih http://code.google.com/p/inih/.

       •   xmltool xmltool/ uses XML.

       •   yajl yajl/ uses JSON.

       Plugins that just show some functionality, (currently) not intended for productive use:

       •   fstab fstab/ reads fstab files.

       •   regexstore regexstore/

       •   simpleini simpleini/ is ini without sections

       •   csvstorage csvstorage/ for csv files

System Information

       Information compiled in Elektra: - version version/ is a build-in plugin directly within the core so that
       it  cannot  give  wrong  version  information - constants constants/ various constants, including version
       information

       Providing information found on the system not available in persistent files:

       •   uname uname/ information from the uname syscall.

Filter

       Filter plugins process keys and their values in both directions. In one direction they undo what they  do
       in  the other direction. Most filter plugins available now encode and decode values. Storage plugins that
       use characters to separate key names, values or metadata will not work without them.

   Encoding
       Rewrite unwanted characters with different techniques:

       •   ccode ccode/ using the technique from arrays in the programming language C

       •   hexcode hexcode/ using hex codes

       Transformations:

       •   keytometa keytometa/ transforms keys to metadata

       •   rename rename/ renames keys according to different rules

       Doing other stuff:

       •   crypto crypto/ encrypts / decrypts confidential values

       •   iconv iconv/ make sure the configuration will have correct character encoding

       •   hidden hidden/ hides keys whose names start with a ..

       •   null null/ takes care of null values and other binary specialities

Notification and Logging

       Log/Send out all changes to configuration to:

       •   dbus dbus/

       •   journald journald/

       •   syslog syslog/

       •   logchange logchange/ prints the change of every key on the console

Debug

       Trace everything that happens within KDB:

       •   timeofday timeofday/ print timestamps

       •   tracer tracer/

       •   counter counter/ count and print how often plugin is used

Checker

       Copies meta data to keys:

       •   glob glob/ using globbing techniques

       •   struct struct/ using a defined structure (may  also  reject  configuration  not  conforming  to  that
           structure)

       Plugins  that  check  if  values  are  valid  based on meta data (typically copied by another plugin just
       before):

       •   validation validation/ by using regex

       •   network network/ by using network APIs

       •   path path/ by checking files on filesystem

       •   type type/ using runtime type checking (CORBA types/)

       •   enum enum/ compares the keyvalue against a list of valid values

       •   mathcheck mathcheck/ by mathematical expressions using keysvalues as operants

       •   conditionals conditionals/ by using if-then-else like statements

Interpreter

       These plugins start an interpreter and allow you to use a bindings.

       •   jni jni/ java plugins started by jni, works with jna plugins

       •   python python/ Python 3 plugins (technical preview/)

       •   python2 python2/ Python 2 plugins (technical preview, deprecated/)

       •   lua lua/ Lua plugins (technical preview/)

Others

       •   doc doc/ contains the documentation of the plugin interface

       •   error error/ yields errors as described in metadata (handy for test purposes)

       •   template template/ to be copied for new plugins

       •   lineendings lineendings/ tests file for consistent line endings

       •   list list/ loads other plugins

       •   filecheck filecheck/ does sanity checks on a file

       To add a new plugin you can copy the template plugin. Please make sure to add your plugin:

       •   to this list, at least in Others

       •   to cmake /cmake/ElektraCache.cmake, at least in ALL

                                                  November 2015                               ELEKTRA-PLUGINS(7)