Config::Model(3pm)

1Config::Model(3)      User Contributed Perl Documentation     Config::Model(3)
2
3
4

NAME

6       Config::Model - a framework to validate, migrate and edit configuration
7       files
8

VERSION

10       version 2.152
11

SYNOPSIS

13   Perl program to use an existing model
14        use Config::Model qw(cme);
15        # load, modify and save popcon configuration file
16        cme('popcon')->modify("PARTICIPATE=yes");
17
18   Command line to use an existing model
19        # with App::Cme
20        cme modify popcon 'PARTICIPATE=yes'
21
22   Perl program with a custom model
23        use Config::Model;
24
25        # create new Model object
26        my $model = Config::Model->new() ; # Config::Model object
27
28        # create config model. A more complex model should be stored in a
29        # file in lib/Config/Model/models. Then, run cme as explained below
30        $model ->create_config_class (
31          name => "MiniModel",
32          element => [ [qw/foo bar baz/ ] => { type => 'leaf', value_type => 'uniline' }, ],
33          rw_config => { backend => 'IniFile', auto_create => 1,
34                         config_dir => '.', file => 'mini.ini',
35                       }
36        ) ;
37
38        # create instance (Config::Model::Instance object)
39        my $instance = $model->instance (root_class_name => 'MiniModel');
40
41        # get configuration tree root
42        my $cfg_root = $instance -> config_root ; # C::M:Node object
43
44        # load some dummy data
45        $cfg_root -> load("bar=BARV foo=FOOV baz=BAZV") ;
46
47        # write new ini file
48        $instance -> write_back;
49
50        # now look for new mini.ini file un current directory
51
52   Create a new model file and use it
53        $ mkdir -p lib/Config/Model/models/
54        $ echo "[ { name => 'MiniModel', \
55                    element => [ [qw/foo bar baz/ ] => { type => 'leaf', value_type => 'uniline' }, ], \
56                    rw_config => { backend => 'IniFile', auto_create => 1, \
57                                   config_dir => '.', file => 'mini.ini', \
58                                 } \
59                  } \
60                ] ; " > lib/Config/Model/models/MiniModel.pl
61        # require App::Cme
62        $ cme modify -try MiniModel -dev bar=BARV foo=FOOV baz=BAZV
63        $ cat mini.ini
64
65       Note that model creation is easier running "cme meta edit" with
66       App::Cme and Config::Model::Itself.
67

DESCRIPTION

69       Config::Model enables a project developer to provide an interactive
70       configuration editor (graphical, curses based or plain terminal) to
71       users.
72
73       To provide these tools, Config::Model needs:
74
75       •   A description of the structure and constraints of the project's
76           configuration (fear not, a GUI is available with App::Cme)
77
78       •   A module to read and write configuration data (aka a backend
79           class).
80
81       With the elements above, Config::Model generates interactive
82       configuration editors (with integrated help and data validation).
83       These editors can be graphical (with Config::Model::TkUI), curses based
84       (with Config::Model::CursesUI) or based on ReadLine.
85
86       Smaller models targeted for configuration upgrades can also be created:
87
88       •   only upgrade and migration specifications are required
89
90       •   unknown parameters can be accepted
91
92       A command line is provided to perform configuration upgrade with a
93       single command.
94
95   How does this work ?
96       Using this project, a typical configuration editor/validator/upgrader
97       is made of 3 parts :
98
99         GUI <--------> |---------------|
100         CursesUI <---> | |---------|   |
101                        | | Model   |   |
102         ShellUI <----> | |---------|   |<-----read-backend------- |-------------|
103                        |               |----write-backend-------> | config file |
104         FuseUI <-----> | Config::Model |                          |-------------|
105                        |---------------|
106
107       1.  A reader and writer that parse the configuration file and transform
108           its data into a tree representation within Config::Model. The
109           values contained in this configuration tree can be written back in
110           the configuration file(s).
111
112       2.  A validation engine which is in charge of validating the content
113           and structure of configuration stored in the configuration tree.
114           This validation engine follows the structure and constraint
115           declared in a configuration model. This model is a kind of schema
116           for the configuration tree.
117
118       3.  A user interface to modify the content of the configuration tree. A
119           modification is validated immediately by the validation engine.
120
121       The important part is the configuration model used by the validation
122       engine. This model can be created or modified with a graphical editor
123       (Config::Model::Iself).
124

Question you may ask yourself

126   Don't we already have some configuration validation tools ?
127       You're probably thinking of tools like webmin. Yes, these tools exist
128       and work fine, but they have their set of drawbacks.
129
130       Usually, the validation of configuration data is done with a script
131       which performs semantic validation and often ends up being quite
132       complex (e.g. 2500 lines for Debian's xserver-xorg.config script which
133       handles "xorg.conf" file).
134
135       In most cases, the configuration model is expressed in instructions
136       (whatever programming language is used) and interspersed with a lot of
137       processing to handle the actual configuration data.
138
139   What's the advantage of this project ?
140       Config::Model projects provide a way to get a validation engine where
141       the configuration model is completely separated from the actual
142       processing instructions.
143
144       A configuration model can be created and modified with the graphical
145       interface provide by Config::Model::Itself. The model is saved in a
146       declarative form (currently, a Perl data structure). Such a model is
147       easier to maintain than a lot of code.
148
149       The model specifies:
150
151       •   The structure of the configuration data (which can be queried by
152           generic user interfaces)
153
154       •   The properties of each element (boundaries check, integer or
155           string, enum like type, default value ...)
156
157       •   The targeted audience (beginner, advanced, master)
158
159       •   The on-line help
160
161       So, in the end:
162
163       •   Maintenance and evolution of the configuration content is easier
164
165       •   User sees a *common* interface for *all* programs using this
166           project.
167
168       •   Upgrade of configuration data is easier and sanity check is
169           performed during the upgrade.
170
171       •   Audit of configuration is possible to check what was modified by
172           the user compared to default values
173
174   What about the user interface ?
175       Config::Model interface can be:
176
177       •   a shell-like interface (plain or based on Term::ReadLine).
178
179       •   Graphical with Config::Model::TkUI (Perl/Tk interface).
180
181       •   based on curses with Config::Model::CursesUI. This interface can be
182           handy if your X server is down.
183
184       •   Through a virtual file system where every configuration parameter
185           is mapped to a file.  (Linux only)
186
187       All these interfaces are generated from the configuration model.
188
189       And configuration model can be created or modified with a graphical
190       user interface (with "cme meta edit" once Config::Model::Itself is
191       installed)
192
193   What about configuration data storage ?
194       Since the syntax of configuration files vary wildly form one
195       application to another, people who want to use this framework may have
196       to provide a dedicated parser/writer.
197
198       To help with this task, this project provides writer/parsers for common
199       format: INI style file and perl file. With the additional
200       Config::Model::Backend::Augeas, Augeas library can be used to read and
201       write some configuration files. See http://augeas.net for more details.
202
203   Is there an example of a configuration model ?
204       The "example" directory contains a configuration model example for
205       "/etc/fstab" file. This example includes a small program that use this
206       model to show some ways to extract configuration information.
207

Mailing lists

209       For more question, please send a mail to:
210
211        config-model-users at lists.sourceforge.net
212

STOP

231       The documentation below is quite detailed and is more a reference doc
232       regarding "Config::Model" class.
233
234       For an introduction to model creation, please check:
235       Config::Model::Manual::ModelCreationIntroduction
236

Storage backend, configuration reader and writer

238       See Config::Model::BackendMgr for details
239

Validation engine

241       "Config::Model" provides a way to get a validation engine from a set of
242       rules. This set of rules is called the configuration model.
243

User interface

245       The user interface uses some parts of the API to set and get
246       configuration values. More importantly, a generic user interface needs
247       to analyze the configuration model to be able to generate at run-time
248       relevant configuration screens.
249
250       A command line interface is provided in this module. Curses and Tk
251       interfaces are provided by Config::Model::CursesUI and
252       Config::Model::TkUI.
253

Constructor

255        my $model = Config::Model -> new ;
256
257       creates an object to host your model.
258
259   Constructor parameters
260       log_level
261           Specify minimal log level. Default is "WARN". Can be "INFO",
262           "DEBUG" or "TRACE" to get more logs. Can also be "ERROR" to get
263           less traces.
264
265           This parameter is used to override the log level specified in log
266           configuration file.
267

Configuration Model

269       To validate a configuration tree, we must create a configuration model
270       that defines all the properties of the validation engine you want to
271       create.
272
273       The configuration model is expressed in a declarative form (i.e. a Perl
274       data structure which should be easier to maintain than a lot of code)
275
276       Each configuration class may contain a set of:
277
278       •   node elements that refer to another configuration class
279
280       •   value elements that contain actual configuration data
281
282       •   list or hash elements that also contain several node or value
283           elements
284
285       The structure of your configuration tree is shaped by the a set of
286       configuration classes that are used in node elements,
287
288       The structure of the configuration data must be based on a tree
289       structure. This structure has several advantages:
290
291       •   Unique path to get to a node or a leaf.
292
293       •   Simpler exploration and query
294
295       •   Simple hierarchy. Deletion of configuration items is simpler to
296           grasp: when you cut a branch, all the leaves attached to that
297           branch go down.
298
299       But using a tree has also some drawbacks:
300
301       •   A complex configuration cannot be mapped on a tree.  Some more
302           relation between nodes and leaves must be added.
303
304       •   A configuration may actually be structured as a graph instead as a
305           tree (for instance, any configuration that maps a service to a
306           resource). The graph relation must be decomposed in a tree with
307           special reference relations that complete the tree to form a graph.
308           See "Value Reference" in Config::Model::Value
309
310       Note: a configuration tree is a tree of objects. The model is declared
311       with classes. The classes themselves have relations that closely match
312       the relation of the object of the configuration tree. But the class
313       need not to be declared in a tree structure (always better to reuse
314       classes). But they must be declared as a DAG (directed acyclic graph).
315       See also Directed acyclic graph on Wikipedia
316       <http://en.wikipedia.org/wiki/Directed_acyclic_graph">More on DAGs>
317
318       Each configuration class declaration specifies:
319
320       •   The "name" of the class (mandatory)
321
322       •   A "class_description" used in user interfaces (optional)
323
324       •   Optional include specification to avoid duplicate declaration of
325           elements.
326
327       •   The class elements
328
329       Each element specifies:
330
331       •   Most importantly, the type of the element (mostly "leaf", or
332           "node")
333
334       •   The properties of each element (boundaries, check, integer or
335           string, enum like type ...)
336
337       •   The default values of parameters (if any)
338
339       •   Whether the parameter is mandatory
340
341       •   Targeted audience (beginner, advance, master), i.e. the level of
342           expertise required to tinker a parameter (to hide expert parameters
343           from newbie eyes)
344
345       •   On-line help (for each parameter or value of parameter)
346
347       See Config::Model::Node for details on how to declare a configuration
348       class.
349
350       Example:
351
352        $ cat lib/Config/Model/models/Xorg.pl
353        [
354          {
355            name => 'Xorg',
356            class_description => 'Top level Xorg configuration.',
357            include => [ 'Xorg::ConfigDir'],
358            element => [
359                        Files => {
360                                  type => 'node',
361                                  description => 'File pathnames',
362                                  config_class_name => 'Xorg::Files'
363                                 },
364                        # snip
365                       ]
366          },
367          {
368            name => 'Xorg::DRI',
369            element => [
370                        Mode => {
371                                 type => 'leaf',
372                                 value_type => 'uniline',
373                                 description => 'DRI mode, usually set to 0666'
374                                }
375                       ]
376          }
377        ];
378

Configuration instance methods

380       A configuration instance is created from a model and is the starting
381       point of a configuration tree.
382
383   instance
384       An instance must be created with a model name (using the root class
385       name) or an application name (as shown by "cme "list"" command).
386
387       For example:
388
389        my $model = Config::Model->new() ;
390        $model->instance( application => 'approx');
391
392       Or:
393
394        my $model = Config::Model->new() ;
395        # note that the model class is slightly different compared to
396        # application name
397        $model->instance( root_class_name => 'Approx');
398
399       A custom configuration class can also be used with "root_class_name"
400       parameter:
401
402        my $model = Config::Model->new() ;
403        # create_config_class is described below
404        $model ->create_config_class (
405          name => "SomeRootClass",
406          element => [ ...  ]
407        ) ;
408
409        # instance name is 'default'
410        my $inst = $model->instance (root_class_name => 'SomeRootClass');
411
412       You can create several separated instances from a model using "name"
413       option:
414
415        # instance name is 'default'
416        my $inst = $model->instance (
417          root_class_name => 'SomeRootClass',
418          name            => 'test1'
419        );
420
421       Usually, model files are loaded automatically using a path matching
422       "root_class_name" (e.g. configuration class "Foo::Bar" is stored in
423       "Foo/Bar.pl". You can choose to specify the file containing the model
424       with "model_file" parameter. This is mostly useful for tests.
425
426       The "instance" method can also retrieve an instance that has already
427       been created:
428
429        my $inst = $model->instance( name => 'test1' );
430
431   get_instance
432       Retrieve an existing instance using its name.
433
434        my $inst = $model->get_instance('test1' );
435
436   has_instance
437       Check if an instance name already exists
438
439         my $maybe = $model->has_instance('test1');
440
441   cme
442       This method is syntactic sugar for short program. It creates a new
443       "Config::Model" object and returns a new instance.
444
445       "cme" arguments are passed to "instance" method, except "force-load".
446
447       Like cme command, "cme" functions accepts "force-load" parameters. When
448       this argument is true, the instance is created with "check =" 'no'>.
449       Hence bad values are stored in "cme" and must be corrected before
450       saving back the data.
451

Configuration class

453       A configuration class is made of series of elements which are detailed
454       in Config::Model::Node.
455
456       Whatever its type (node, leaf,... ), each element of a node has several
457       other properties:
458
459       level
460           Level is "important", "normal" or "hidden".
461
462           The level is used to set how configuration data is presented to the
463           user in browsing mode. "Important" elements are shown to the user
464           no matter what. "hidden" elements are well, hidden. Their purpose
465           is explained with the warp notion.
466
467       status
468           Status is "obsolete", "deprecated" or "standard" (default).
469
470           Using a deprecated element raises a warning. Using an obsolete
471           element raises an exception.
472
473       description
474           Description of the element. This description is used while
475           generating user interfaces.
476
477       summary
478           Summary of the element. This description is used while generating a
479           user interfaces and may be used in comments when writing the
480           configuration file.
481
482       class_description
483           Description of the configuration class. This description is used
484           while generating user interfaces.
485
486       generated_by
487           Mention with a descriptive string if this class was generated by a
488           program.  This parameter is currently reserved for
489           Config::Model::Itself model editor.
490
491       include
492           Include element description from another class.
493
494             include => 'AnotherClass' ,
495
496           or
497
498             include => [qw/ClassOne ClassTwo/]
499
500           In a configuration class, the order of the element is important.
501           For instance if "foo" is warped by "bar", you must declare "bar"
502           element before "foo".
503
504           When including another class, you may wish to insert the included
505           elements after a specific element of your including class:
506
507             # say AnotherClass contains element xyz
508             include => 'AnotherClass' ,
509             include_after => "foo" ,
510             element => [ bar => ... , foo => ... , baz => ... ]
511
512           Now the element of your class are:
513
514             ( bar , foo , xyz , baz )
515
516           Note that include may not clobber an existing element.
517
518       include_backend
519           Include read/write specification from another class.
520
521             include_backend => 'AnotherClass' ,
522
523           or
524
525             include_backend => [qw/ClassOne ClassTwo/]
526
527       Note that include may not clobber an existing read/write specification.
528
529   create_config_class
530       This method creates configuration classes. The parameters are described
531       above and are forwarded to Config::Model::Node constructor. See
532       "Configuration class declaration" in Config::Model::Node for more
533       details on configuration class parameters.
534
535       Example:
536
537         my $model = Config::Model -> new ;
538
539         $model->create_config_class
540         (
541          config_class_name => 'SomeRootClass',
542          description       => [ X => 'X-ray' ],
543          level             => [ 'tree_macro' => 'important' ] ,
544          class_description => "SomeRootClass description",
545          element           => [ ... ]
546         ) ;
547
548       For convenience, "level" and "description" parameters can also be
549       declared within the element declaration:
550
551         $model->create_config_class
552         (
553          config_class_name => 'SomeRootClass',
554          class_description => "SomeRootClass description",
555          'element'
556          => [
557               tree_macro => { level => 'important'},
558               X          => { description => 'X-ray', } ,
559             ]
560         ) ;
561

Load predeclared model

563       You can also load predeclared model.
564
565   load( <model_name> )
566       This method opens the model directory and execute a ".pl" file
567       containing the model declaration,
568
569       This perl file must return an array ref to declare models. E.g.:
570
571        [
572         [
573          name => 'Class_1',
574          element => [ ... ]
575         ],
576         [
577          name => 'Class_2',
578          element => [ ... ]
579         ]
580        ];
581
582       do not put "1;" at the end or "load" will not work
583
584       When a model name contain a "::" (e.g "Foo::Bar"), "load" looks for a
585       file named "Foo/Bar.pl".
586
587       This method also searches in "Foo/Bar.d" directory for additional model
588       information.  Model snippet found there are loaded with
589       augment_config_class.
590
591       Returns a list containing the names of the loaded classes. For
592       instance, if "Foo/Bar.pl" contains a model for "Foo::Bar" and
593       "Foo::Bar2", "load" returns "( 'Foo::Bar' , 'Foo::Bar2' )".
594
595   augment_config_class (name => '...', class_data )
596       Enhance the feature of a configuration class. This method uses the same
597       parameters as create_config_class. See "Model Plugin" in
598       Config::Model::Manual::ModelCreationAdvanced for more details on
599       creating model plugins.
600

Model query

602   model
603       Returns a hash containing the model declaration of the passed model
604       name. Do not modify the content of the returned data structure.
605
606        my $cloned = $model->model('Foo');
607
608   get_model_clone
609       Like "model", returns a hash containing the model declaration of the
610       passed model name, this time in a deep clone of the data structure.
611
612        my $cloned = $model->get_model_clone('Foo');
613
614   generate_doc ( top_class_name , directory , [ \%done ] )
615       Generate POD document for configuration class top_class_name and all
616       classes used by top_class_name, and write them in specified directory.
617
618       "\%done" is an optional reference to a hash used to avoid writing twice
619       the same documentation when this method is called several times.
620
621   get_element_model( config_class_name , element)
622       Return a hash containing the model declaration for the specified class
623       and element.
624
625   get_element_name( class => Foo )
626       Get all names of the elements of class "Foo".
627
628   get_element_property
629       Returns the property of an element from the model.
630
631       Parameters are:
632
633       class
634       element
635       property
636
637   list_class_element
638       Returns a string listing all the class and elements. Useful for
639       debugging your configuration model.
640

Error handling

642       Errors are handled with an exception mechanism.
643
644       When a strongly typed Value object gets an authorized value, it raises
645       an exception. If this exception is not caught, the programs exits.
646
647       See Config::Model::Exception for details on the various exception
648       classes provided with "Config::Model".
649

Logging

651       See "Logging" in cme
652
653   initialize_log4perl
654       This method can be called to load Log::Log4perl configuration from
655       "~/.log4config-model", or from "/etc/log4config-model.conf" files or
656       from default configuration <https://github.com/dod38fr/config-
657       model/blob/master/lib/Config/Model/log4perl.conf>.
658
659       Accepts "verbose" parameter with a list of log classes that are added
660       to the log4perl configuration read above.
661
662       For instance, with "verbose => 'Loader'", log4perl is initialised with
663
664        log4perl.logger.Verbose.Loader = INFO, PlainMsgOnScreen
665
666       Likewise, with "verbose => [ 'Loader', 'Foo' ]", log4perl is
667       initialised with:
668
669        log4perl.logger.Verbose.Loader = INFO, PlainMsgOnScreen
670        log4perl.logger.Verbose.Foo    = INFO, PlainMsgOnScreen
671
672       Currently, this module supports only "Loader" as verbose parameters.
673

BUGS

675       Given Murphy's law, the author is fairly confident that you will find
676       bugs or miss some features. Please report them to
677       https://github.com/dod38fr/config-model/issues The author will be
678       notified, and then you'll automatically be notified of progress on your
679       bug.
680

FEEDBACK

682       Feedback from users are highly desired. If you find this module useful,
683       please share your use cases, success stories with the author or with
684       the config-model- users mailing list.
685

PROJECT FOUNDER

687       Dominique Dumont, "ddumont@cpan.org"
688

CREDITS

690       Contributors to this project are listed in alphabetical order:
691
692         Harley Pig
693
694         Ilya Arosov
695
696         Jose Luis Perez Diez
697
698         Krzysztof Tyszecki
699
700         Mathieu Arnold
701
702         Mohammad S Anwar
703
704         Topi Miettinen
705
706       Many thanks for your help
707

AUTHOR

784       Dominique Dumont
785

COPYRIGHT AND LICENSE

787       This software is Copyright (c) 2005-2022 by Dominique Dumont.
788
789       This is free software, licensed under:
790
791         The GNU Lesser General Public License, Version 2.1, February 1999
792

SUPPORT

794   Websites
795       The following websites have more information about this module, and may
796       be of help to you. As always, in addition to those websites please use
797       your favorite search engine to discover more resources.
798
799       •   CPANTS
800
801           The CPANTS is a website that analyzes the Kwalitee ( code metrics )
802           of a distribution.
803
804           <http://cpants.cpanauthors.org/dist/Config-Model>
805
806       •   CPAN Testers
807
808           The CPAN Testers is a network of smoke testers who run automated
809           tests on uploaded CPAN distributions.
810
811           <http://www.cpantesters.org/distro/C/Config-Model>
812
813       •   CPAN Testers Matrix
814
815           The CPAN Testers Matrix is a website that provides a visual
816           overview of the test results for a distribution on various
817           Perls/platforms.
818
819           <http://matrix.cpantesters.org/?dist=Config-Model>
820
821       •   CPAN Testers Dependencies
822
823           The CPAN Testers Dependencies is a website that shows a chart of
824           the test results of all dependencies for a distribution.
825
826           <http://deps.cpantesters.org/?module=Config::Model>
827
828   Bugs / Feature Requests
829       Please report any bugs or feature requests by email to "ddumont at
830       cpan.org", or through the web interface at
831       <https://github.com/dod38fr/config-model/issues>. You will be
832       automatically notified of any progress on the request by the system.
833
834   Source Code
835       The code is open to the world, and available for you to hack on. Please
836       feel free to browse it and play with it, or whatever. If you want to
837       contribute patches, please send me a diff or prod me to pull from your
838       repository :)
839
840       <http://github.com/dod38fr/config-model>
841
842         git clone git://github.com/dod38fr/config-model.git
843
844
845
846perl v5.36.0                      2022-08-10                  Config::Model(3)

NAME

VERSION

SYNOPSIS

DESCRIPTION

Question you may ask yourself

Mailing lists

Suggested reads to start

STOP

Storage backend, configuration reader and writer

Validation engine

User interface

Constructor

Configuration Model

Configuration instance methods

Configuration class

Load predeclared model

Model query

Error handling

Logging

BUGS

FEEDBACK

PROJECT FOUNDER

CREDITS

SEE ALSO

AUTHOR

COPYRIGHT AND LICENSE

SUPPORT