/ 
Config-Processor-0.28
River stage one • 1 direct dependent • 5 total dependents
/ Config::Processor

NAME

Config::Processor - Cascading configuration files processor with additional features

SYNOPSIS

use Config::Processor;

my $config_processor = Config::Processor->new(
  dirs => [qw( /etc/myapp /home/username/etc/myapp )]
);

my $config = $config_processor->load(qw( dirs.yml db.json metrics/* ));

$config = $config_processor->load(
  qw( dirs.yml db.json redis.yml mongodb.json metrics/* ),

  { myapp => {
      db => {
        connectors => {
          stat_master => {
            host => 'localhost',
            port => '4321',
          },
        },
      },
    },
  },
);

DESCRIPTION

Config::Processor is the cascading configuration files processor, which supports file inclusions, variables interpolation and other manipulations with configuration tree. Works with YAML and JSON file formats. File format is determined by the extension. Supports following file extensions: .yml, .yaml, .jsn, .json.

CONSTRUCTOR

new( %params )

my $config_processor = Config::Processor->new(
  dirs       => [qw( /etc/myapp /home/username/etc/myapp )],
  export_env => 1,
);

$config_processor = Config::Processor->new;

$config_processor = Config::Processor->new(
  dirs                  => [qw( /etc/myapp /home/username/etc/myapp )],
  interpolate_variables => 0,
  process_directives    => 0,
);
dirs => \@dirs

List of directories, in which configuration processor will search files. If the parameter not specified, current directory will be used.

interpolate_variables => $boolean

Enables or disables variable interpolation in configurations files. Enabled by default.

process_directives => $boolean

Enables or disables directive processing in configurations files. Enabled by default.

export_env => $boolean

Enables or disables environment variables exporting to configuration tree. If enabled, environment variables can be accessed by the key ENV from the configuration tree and can be interpolated into other configuration parameters.

Disabled by default.

METHODS

load( @config_sections )

Attempts to load all configuration sections and returns reference to resulting configuration tree.

Configuration section can be a relative filename, a filename with wildcard characters or a hash reference. Filenames with wildcard characters is processed by CORE::glob function and supports the same syntax.

my $config = $config_processor->load( qw( myapp.yml extras/* ), \%hard_config );

interpolate_variables( [ $boolean ] )

Enables or disables variable interpolation in configurations files.

process_directives( [ $boolean ] )

Enables or disables directive processing in configuration files.

export_env( [ $boolean ] )

Enables or disables environment variables exporting to configuration tree.

MERGING RULES

Config::Processor merges all configuration sections in one resulting configuration tree by following rules:

Left value  Right value  Result value

SCALAR $a   SCALAR $b    SCALAR $b
SCALAR $a   ARRAY  \@b   ARRAY  \@b
SCALAR $a   HASH   \%b   HASH   \%b

ARRAY \@a   SCALAR $b    SCALAR $b
ARRAY \@a   ARRAY  \@b   ARRAY  \@b
ARRAY \@a   HASH   \%b   HASH   \%b

HASH \%a    SCALAR $b    SCALAR $b
HASH \%a    ARRAY  \@b   ARRAY  \@b
HASH \%a    HASH   \%b   HASH   recursive_merge( \%a, \%b )

For example, we have two configuration files. db.yml at the left side:

db:
  connectors:
    stat_writer:
      host:     "stat.mydb.com"
      port:     "1234"
      dbname:   "stat"
      username: "stat_writer"
      password: "stat_writer_pass"

And db_test.yml at the right side:

db:
  connectors:
    stat_writer:
      host:     "localhost"
      username: "test"
      password: "test_pass"

After merging of two files we will get:

db => {
  connectors => {
    stat_writer => {
      host      => "localhost",
      port:     => "1234",
      dbname:   => "stat",
      username: => "test",
      password: => "test_pass",
    },
  },
},

INTERPOLATION

Config::Processor can interpolate variables in string values (if you need alias for complex structures see var directive). Variable names can be absolute or relative. Relative variable names begins with "." (dot). The number of dots depends on the nesting level of the current configuration parameter relative to referenced configuration parameter.

myapp:
  media_formats: [ "images", "audio", "video" ]

  dirs:
    root_dir: "/myapp"
    templates_dir: "${myapp.dirs.root_dir}/templates"
    sessions_dir: "${.root_dir}/sessions"
    media_dirs:
      - "${..root_dir}/media/${myapp.media_formats.0}"
      - "${..root_dir}/media/${myapp.media_formats.1}"
      - "${..root_dir}/media/${myapp.media_formats.2}"

After processing of the file we will get:

myapp => {
  media_formats => [ "images", "audio", "video" ],

  dirs => {
    root_dir      => "/myapp",
    templates_dir => "/myapp/templates",
    sessions_dir  => "/myapp/sessions",
    media_dirs    => [
      "/myapp/media/images",
      "/myapp/media/audio",
      "/myapp/media/video",
    ],
  },
},

To escape variable interpolation add one more "$" symbol before variable.

templates_dir: "$${myapp.dirs.root_dir}/templates"

After processing we will get:

templates_dir => ${myapp.dirs.root_dir}/templates,

DIRECTIVES

var: varname

Assigns configuration parameter value to another configuration parameter. Variable names in the directive can be absolute or relative. Relative variable names begins with "." (dot). The number of dots depends on the nesting level of the current configuration parameter relative to referenced configuration parameter.

myapp:
  db:
    default_options:
      PrintWarn:  0
      PrintError: 0
      RaiseError: 1

    connectors:
      stat_master:
        host:     "stat-master.mydb.com"
        port:     "1234"
        dbname:   "stat"
        username: "stat_writer"
        password: "stat_writer_pass"
        options: { var: myapp.db.default_options }

      stat_slave:
        host:     "stat-slave.mydb.com"
        port:     "1234"
        dbname:   "stat"
        username: "stat_reader"
        password: "stat_reader_pass"
        options: { var: ...default_options }
include: filename

Loads configuration parameters from file or multiple files and assigns it to specified configuration parameter. Argument of include directive can be relative filename or a filename with wildcard characters. If loading multiple files, configuration parameters from them will be merged before assignment.

myapp:
  db:
    generic_options:
      PrintWarn:  0
      PrintError: 0
      RaiseError: 1

    connectors: { include: db_connectors.yml }

  metrics: { include: metrics/* }
underlay

Merges specified configuration parameters with parameters located at the same context. Configuration parameters from the context overrides parameters from the directive. underlay directive most usefull in combination with var and include directives.

For example, you can use this directive to set default values of parameters.

myapp:
  db:
    connectors:
      default:
        port:   "1234"
        dbname: "stat"
        options:
          PrintWarn:  0
          PrintError: 0
          RaiseError: 1

      stat_master:
        underlay: { var: .default }
        host:     "stat-master.mydb.com"
        username: "stat_writer"
        password: "stat_writer_pass"

      stat_slave:
        underlay: { var: .default }
        host:     "stat-slave.mydb.com"
        username: "stat_reader"
        password: "stat_reader_pass"

You can move default parameters in separate files.

myapp:
  db:
    connectors:
      underlay:
        - { include: db_connectors/default.yml }
        - { include: db_connectors/default_test.yml }

      stat_master:
        underlay: { var: .default }
        host:     "stat-master.mydb.com"
        username: "stat_writer"
        password: "stat_writer_pass"

      stat_slave:
        underlay: { var: .default }
        host:     "stat-slave.mydb.com"
        username: "stat_reader"
        password: "stat_reader_pass"

      test:
        underlay: { var: .default_test }
        username: "test"
        password: "test_pass"
overlay

Merges specified configuration parameters with parameters located at the same context. Configuration parameters from the directive overrides parameters from the context. overlay directive most usefull in combination with var and include directives.

For example, you can use overlay directive to temporaly overriding regular configuration parameters.

myapp:
  db:
    connectors:
      default:
        port:   "1234"
        dbname: "stat"
        options:
          PrintWarn:  0
          PrintError: 0
          RaiseError: 1

      test:
        host: "localhost"
        port: "4321"

      stat_master:
        underlay: { var: .default }
        host:     "stat-master.mydb.com"
        username: "stat_writer"
        password: "stat_writer_pass"
        overlay:  { var: .test }

      stat_slave:
        underlay: { var: .default }
        host:     "stat-slave.mydb.com"
        username: "stat_reader"
        password: "stat_reader_pass"
        overlay:  { var: .test }

To disable overriding just assign to test connector empty hash.

test: {}

AUTHOR

Eugene Ponizovsky, <ponizovsky@gmail.com>

COPYRIGHT AND LICENSE

Copyright (c) 2016-2018, Eugene Ponizovsky, <ponizovsky@gmail.com>. All rights reserved.

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.