1Config::Model::BackendMUgsre(r3)Contributed Perl DocumenCtoantfiiogn::Model::BackendMgr(3)
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6 Config::Model::BackendMgr - Load configuration node on demand
7
9 version 2.129
10
12 # Use BackendMgr to write data in Yaml file
13 use Config::Model;
14 # define configuration tree object
16 my $model = Config::Model->new;
17 $model->create_config_class(
18 name => "Foo",
19 element => [
20 [qw/foo bar/] => {
21 type => 'leaf',
22 value_type => 'string'
23 },
24 ]
25 );
26 $model->create_config_class(
28 name => "MyClass",
29 # rw_config spec is used by Config::Model::BackendMgr
31 rw_config => {
32 backend => 'yaml',
33 config_dir => '/tmp/',
34 file => 'my_class.yml',
35 auto_create => 1,
36 },
37 element => [
39 [qw/foo bar/] => {
40 type => 'leaf',
41 value_type => 'string'
42 },
43 hash_of_nodes => {
44 type => 'hash', # hash id
45 index_type => 'string',
46 cargo => {
47 type => 'node',
48 config_class_name => 'Foo'
49 },
50 },
51 ],
52 );
53 my $inst = $model->instance( root_class_name => 'MyClass' );
55 my $root = $inst->config_root;
57 # put data
59 my $steps = 'foo=FOO hash_of_nodes:fr foo=bonjour -
60 hash_of_nodes:en foo=hello ';
61 $root->load( steps => $steps );
62 $inst->write_back;
64 # now look at file /tmp/my_class.yml
66
68 This class provides a way to specify how to load or store configuration
69 data within the model.
70 With these specifications, all configuration information is read during
72 creation of a node (which triggers the creation of a backend manager
73 object) and written back when write_back method is called (either on
74 the node or on this backend manager).
75 This load/store can be done with different backends:
77 · Any of the "Config::Model::Backend::*" classes available on your
79 system. For instance "Config::Model::Backend::Yaml".
80 · "cds_file": Config dump string (cds) in a file. I.e. a string that
82 describes the content of a configuration tree is loaded from or
83 saved in a text file. This format is defined by this project. See
84 "load string syntax" in Config::Model::Loader.
85 · "perl_file": Perl data structure (perl) in a file. See
87 Config::Model::DumpAsData for details on the data structure. Now
88 handled by Config::Model::Backend::PerlFile
89 When needed, "write_back" method can be called on the instance (See
91 Config::Model::Instance) to store back all configuration information.
92
94 The backend specification is provided as an attribute of a
95 Config::Model::Node specification. These attributes are optional: A
96 node without "rw_config" attribute must rely on another node to read or
97 save its data.
98 When needed (usually for the root node), the configuration class is
100 declared with a "rw_config" parameter which specifies the read/write
101 backend configuration.
102 Parameters available for all backends
104 The following parameters are accepted by all backends:
105 config_dir
107 Specify configuration directory. This parameter is optional as the
108 directory can be hardcoded in the backend class. "config_dir"
109 beginning with '"~"' is munged so "~" is replaced by
110 "File::HomeDir->my_data". See File::HomeDir for details.
111 file
113 Specify configuration file name (without the path). This parameter
114 is optional as the file name can be hardcoded in the backend class.
115 The configuration file name can be specified with &index keyword
117 when a backend is associated to a node contained in a hash. For
118 instance, with "file" set to "&index.conf":
119 service # hash element
121 foo # hash index
122 nodeA # values of nodeA are stored in foo.conf
123 bar # hash index
124 nodeB # values of nodeB are stored in bar.conf
125 Likewise, the keyword &element can be used to specify the file
127 name. For instance, with "file" set to "&element-&index.conf":
128 service # hash element
130 foo # hash index
131 nodeA # values of nodeA are stored in service.foo.conf
132 bar # hash index
133 nodeB # values of nodeB are stored in service.bar.conf
134 file_mode
136 "file_mode" parameter can be used to set the mode of the written
137 file(s). "file_mode" value can be in any form supported by "chmod"
138 in Path::Tiny. Example:
139 file_mode => 0664,
141 file_mode => '0664',
142 file_mode => 'g+w'
143 os_config_dir
145 Specify alternate location of a configuration directory depending
146 on the OS (as returned by $^O, see "PLATFORMS" in perlport). For
147 instance:
148 config_dir => '/etc/ssh',
150 os_config_dir => { darwin => '/etc' }
151 default_layer
153 Optional. Specifies where to find a global configuration file that
154 specifies default values. For instance, this is used by OpenSSH to
155 specify a global configuration file ("/etc/ssh/ssh_config") that is
156 overridden by user's file:
157 default_layer => {
159 os_config_dir => { 'darwin' => '/etc' },
160 config_dir => '/etc/ssh',
161 file => 'ssh_config'
162 }
163 Only the 3 above parameters can be specified in "default_layer".
165 auto_create
167 By default, an exception is thrown if no read was successful. This
168 behavior can be overridden by specifying "auto_create => 1" in one
169 of the backend specification. For instance:
170 rw_config => {
172 backend => 'IniFile',
173 config_dir => '/tmp',
174 file => 'foo.conf',
175 auto_create => 1
176 },
177 Setting "auto_create" to 1 is necessary to create a configuration
179 from scratch
180 auto_delete
182 Delete configuration files that contains no data. (default is to
183 leave an empty file)
184 Config::Model::Backend::* backends
186 Specify the backend name and the parameters of the backend defined in
187 their documentation.
188 For instance:
190 rw_config => {
192 backend => 'yaml',
193 config_dir => '/tmp/',
194 file => 'my_class.yml',
195 },
196 See Config::Model::Backend::Yaml for more details for this backend.
198 Your own backend
200 You can also write a dedicated backend. See How to write your own
201 backend for details.
202
204 By default, configurations files are read from the directory specified
205 by "config_dir" parameter specified in the model. You may override the
206 "root" directory for test.
207
209 support_annotation
210 Returns 1 if at least the backend supports read and write annotations
211 (aka comments) in the configuration file.
212
214 Dominique Dumont, (ddumont at cpan dot org)
215
217 Config::Model, Config::Model::Instance, Config::Model::Node,
218 Config::Model::Dumper
219
221 Dominique Dumont
222
224 This software is Copyright (c) 2005-2018 by Dominique Dumont.
225 This is free software, licensed under:
227 The GNU Lesser General Public License, Version 2.1, February 1999
229perl v5.28.1 2018-12-07 Config::Model::BackendMgr(3)