NAME

Config::Abstraction - Configuration Abstraction Layer

VERSION

Version 0.09

SYNOPSIS

use Config::Abstraction;

my $config = Config::Abstraction->new(
  config_dirs => ['config'],
  env_prefix => 'MYAPP_',
  flatten => 0,
);

my $db_user = $config->get('database.user');

DESCRIPTION

Config::Abstraction is a flexible configuration management layer that sits above Config::* modules. In addition to using drivers to load configuration data from multiple file formats (YAML, JSON, XML, and INI), it also allows levels of configuration, each of which overrides the lower levels. So, it also integrates environment variable overrides and command line arguments for runtime configuration adjustments. This module is designed to help developers manage layered configurations that can be loaded from files and overridden by at run-time for debugging, offering a modern, robust and dynamic approach to configuration management.

KEY FEATURES

• Multi-Format Support

  Supports configuration files in YAML, JSON, XML, and INI formats. Automatically merges configuration data from these different formats, allowing hierarchical configuration management.

• Environment Variable Overrides

  Allows environment variables to override values in the configuration files. By setting environment variables with a specific prefix (default: APP_), values in the configuration files can be dynamically adjusted without modifying the file contents.

• Flattened Configuration Option

  Optionally supports flattening the configuration structure. This converts deeply nested configuration keys into a flat key-value format (e.g., database.user instead of database-{user}>). This makes accessing values easier for applications that prefer flat structures or need compatibility with flat key-value stores.

• Layered Configuration

  Supports merging multiple layers of configuration files. For example, you can have a base.yaml configuration file that provides default values, and a local.yaml (or local.json, local.xml, etc.) file that overrides specific values. This allows for environment-specific configurations while keeping defaults intact.

• Merge Strategy

  The module merges the configuration data intelligently, allowing values in more specific files (like local.yaml, local.json, local.xml, local.ini) to override values in base files. This enables a flexible and layered configuration system where you can set defaults and override them for specific environments.

• Error Handling

  Includes error handling for loading configuration files. If any file fails to load (e.g., due to syntax issues), the module will throw descriptive error messages to help with debugging.

SUPPORTED FILE FORMATS

• YAML (*.yaml, *.yml)

  The module supports loading YAML files using the YAML::XS module.

• JSON (*.json)

  The module supports loading JSON files using JSON::MaybeXS.

• XML (*.xml)

  The module supports loading XML files using XML::Simple.

• INI (*.ini)

  The module supports loading INI files using Config::IniFiles.

ENVIRONMENT VARIABLE HANDLING

Configuration values can be overridden via environment variables. For instance, if you have a key in the configuration such as database.user, you can override it by setting the corresponding environment variable APP_DATABASE__USER in your system.

For example:

$ export APP_DATABASE__USER="env_user"

This will override any value set for database.user in the configuration files.

COMMAND LINE HANDLING

Configuration values can be overridden via the command line (@ARGV). For instance, if you have a key in the configuration such as database.user, you can override it by adding "APP_DATABASE__USER=other_user_name" to the command line arguments. This will override any value set for database.user in the configuration files.

EXAMPLE CONFIGURATION FLOW

• 1. Loading Files

  The module first looks for configuration files in the specified directories. It loads the following files in order of preference: base.yaml, local.yaml, base.json, local.json, base.xml, local.xml, base.ini, and local.ini.

  If config_file or config_files is set, those files are loaded last.

• 1. Merging and Resolving

  The module merges the contents of these files, with more specific configurations (e.g., local.*) overriding general ones (e.g., base.*).

• 1. Environment Overrides

  After loading and merging the configuration files, environment variables are checked and used to override any conflicting settings.

• 1. Command Line

  Next, the command line arguments are checked and used to override any conflicting settings.

• 1. Accessing Values

  Values in the configuration can be accessed using a dotted notation (e.g., 'database.user'), regardless of the file format used.

METHODS

new

Constructor for creating a new configuration object.

Options:

• config_dirs

  An arrayref of directories to look for configuration files (default: [$HOME/.conf], [$DOCUMENT_ROOT/conf], or ['conf']).

• config_file

  Points to a configuration file of any format.

• config_files

  An arrayref of files to look for in the configuration directories. Put the more important files later, since later files override earlier ones.

• env_prefix

  A prefix for environment variable keys and comment line options, e.g. MYAPP_DATABASE__USER, (default: 'APP_').

• flatten

  If true, returns a flat hash structure like {database.user} (default: 0) instead of {database}{user}. ` =item * logger

  Used for warnings and traces. An object that understands warn(), debug() and trace() messages.

• path

  A synonym of config_dirs.

• sep_char

  The separator in keys. The default is a '.', as in dotted notation, such as 'database.user'.

get(key)

Retrieve a configuration value using dotted key notation (e.g., 'database.user'). Returns undef if the key doesn't exist.

all()

Returns the entire configuration hash, possibly flattened depending on the flatten option.

The entry config_path contains a colon separated list of the files that the configuration was loaded from.

BUGS

It should be possible to escape the separator character either with backslashes or quotes.

SUPPORT

This module is provided as-is without any warranty.

Please report any bugs or feature requests to bug-config-abstraction at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Config-Abstraction. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

You can find documentation for this module with the perldoc command.

perldoc Config::Abstraction

SEE ALSO

• Config::Auto
• Log::Abstraction

AUTHOR

Nigel Horne, <njh at nigelhorne.com>