Config::Structured - provides generalized and structured configuration value access

Basic usage:

use Config::Structured;

my $conf = Config::Structured->new(
  structure => { 
    db => {
      host     => {
        isa         => 'Str',
        default     => 'localhost',
        description => 'the database server hostname',
      },
      username => {
        isa         => 'Str',
        default     => 'dbuser',
        description => 'the database user's username',
      },
      password => {
        isa         => 'Str',
        description => 'the database user's password',
      },
    }
  },
  config => { 
    db => {
      username => 'appuser',
      host     => {
        source   => 'env',
        ref      => 'DB_HOSTNAME',
      },
      password => {
        source => 'file',
        ref    => '/run/secrets/db_password',
      },
    }
  }
);

say $conf->db->username(); # appuser
# assuming that the hostname value has been set in the DB_HOSTNAME env var
say $conf->db->host; # prod_db_1.mydomain.com
# assuming that the password value has been stored in /run/secrets/db_password
say $conf->db->password(); # *mD9ua&ZSVzEeWkm93bmQzG

Hooks example showing how to ensure config directories exist prior to first use:

my $conf = Config::Structured->new(
  ...
  hooks => {
    '/paths/*' => {
      on_load => sub($node,$value) {
        Mojo::File->new($value)->make_path
      }
    }
  }
)

Config::Structured provides a structured method of accessing configuration values

This is predicated on the use of a configuration structure (required), This structure provides a hierarchical structure of configuration branches and leaves. Each branch becomes a Config::Structured method which returns a new Config::Structured instance rooted at that node, while each leaf becomes a method which returns the configuration value.

The configuration value is normally provided in the config hash. However, a config node for a non-Hash value can be a hash containing the "source" and "ref" keys. This permits sourcing the config value from a file (when source="file") whose filesystem location is given in the "ref" value, or an environment variable (when source="env") whose name is given in the "ref" value.

Structure Leaf Nodes are required to include an "isa" key, whose value is a type (see Moose::Util::TypeConstraints). If typechecking is not required, use isa => 'Any'. There are a few other keys that Config::Structured respects in a leaf node:

• default

  This key's value is the default configuration value if a data source or value is not provided by the configuation.

• description

• notes

  A human-readable description and implementation notes, respectively, of the configuration node. Config::Structured does not do anything with these values at present, but they provides inline documentation of configuration directivess within the structure (particularly useful in the common case where the structure is read from a file)

Besides structure and config, Config::Structured also accepts a hooks argument at initialization time. This argument must be a HashRef whose keys are patterns matching config node paths, and whose values are HashRefs containing on_load and/or on_access keys. These in turn point to CodeRefs which are run when the config value is initially loaded, or every time it is accessed, respectively.

Returns a new Config::Structured instance. config and structure are required parameters and must either be HashRefs or strings containing a data structure in JSON, YAML, or perl (i.e., Data::Dumper) formats. The format of the structure will be autodetected. The content of these data structures is detailed above in the DESCRIPTION section.

Class method.

Returns a registered Config::Structured instance. If $name is not provided, returns the default instance. Instances can be registered with __register_default or __register_as. This mechanism is used to provide global access to a configuration, even from code contexts that otherwise cannot share data.

Call on a Config::Structured instance to set the instance as the default.

Call on a Config::Structured instance to register the instance as the provided name.

Returns a list of names (strings) of all immediate child nodes of the current config node

Mark Tyrrell <mark@tyrrminal.dev>

Copyright (c) 2024 Mark Tyrrell

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.