Class: FeduxOrgStdlib::AppConfig

Inherits:
Object
  • Object
show all
Defined in:
lib/fedux_org_stdlib/app_config.rb,
lib/fedux_org_stdlib/app_config/exceptions.rb

Overview

This class makes a config file available as an object. The config file needs to be ‘YAML` by default. It is read by `Psych` and converted to a hash. If you chose to use a different file format: Each config file needs to translatable to a hash or another data structure which responds to `[]` by the given `config_engine`. If no suitable config file can be found the config uses only the defined defaults within the class.

By default it will look for a suitable config file in the given order:

  1. $HOME/.config/<application_name>/<config_file>.yaml

  2. $HOME/.<application_name>/<config_file>.yaml

  3. $HOME/.<config_file>.yaml

  4. $HOME/.<config_file>rc

  5. /etc/.<application_name>/<config_file>.yaml

Please keep in mind

  • application_name: Module of your class, e.g. “MyApplication” becomes “my_application”

  • config_file: Pluarized name of your class and “Config” strip off, e.g “ClientConfig” becomes “clients.yaml” (mind the pluralized name)

Most conventions defined by me are implemented as separate methods. If one convention is not suitable for your use case, just overwrite the method.

If you prefer to use a different path to the config file or name of the config file one of the following methods needs to be overwritten:

  • config_file

  • config_name

  • application_name

If you want the class to look for your config file at a different place overwrite the following method

  • allowed_config_file_paths

Below you find some examples for the usage of the class:

Examples:

Create config with one writer and reader

module MyApplication
  class ClientConfig < AppConfig
    # 'data1' is the default for option1
    # if you create a file
    option :option1, 'data1'
  end
end

Create config with a reader only

module MyApplication
  class ClientConfig < AppConfig
    # 'data1' is the default for option1
    # if you create a file
    option_reader :option1, 'data1'
  end
end

Config yaml file for the classes above: clients.yaml

---
option1: 'data2'

Defined Under Namespace

Modules: Exceptions

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(file: _available_config_file, config_engine: Psych, logger: FeduxOrgStdlib::Logging::Logger.new, check_unknown_options: true) ⇒ AppConfig

Create a new instance of config

It tries to find a suitable configuration file. If it doesn’t find one the config is empty and uses the defaults defined within a config class

Parameters:

  • file (String) (defaults to: _available_config_file) —

    Path where config file is stored. The file will be read by the ‘config_engine`.

  • config_engine (Object) (defaults to: Psych) —

    (Psych) The engine to read config file

  • check_unknown_options (true, false) (defaults to: true) —

    Should a warning be put to stdout if there are unknown options in yaml config file

Raises:



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# File 'lib/fedux_org_stdlib/app_config.rb', line 183

def initialize(
  file: _available_config_file,
  config_engine: Psych,
  logger: FeduxOrgStdlib::Logging::Logger.new,
  check_unknown_options: true
)
  @logger = logger

  unless file
    logger.debug "No configuration file found at #{_allowed_config_file_paths.to_list}, therefor I'm going to use an empty config object instead."
    @__config = {}

    return
  end

  begin
    yaml = config_engine.safe_load(File.read(file), [Symbol])
  rescue StandardError => e
    raise Exceptions::ConfigFileNotReadable, JSON.dump(message: e.message, file: file)
  end

  if yaml.blank?
    @__config = {}
  elsif yaml.is_a? Hash
    yaml = yaml.deep_symbolize_keys

    yaml_withknown_options = yaml.deep_symbolize_keys.slice(*known_options)
    unknown_options = yaml.keys - yaml_withknown_options.keys

    logger.warn "Unknown config options #{(unknown_options).to_list} in config file #{file} detected. Please define them in your config class or remove the entries in your config file or disable check via `check_unknown_options: false` to get rid of this warning." unless unknown_options.blank? && check_unknown_options == true

    @__config = Hash(yaml_withknown_options)
  else
    logger.warn "There seems to be a problem transforming config file \"#{file}\" to a hash, therefor I will use an empty config object."
    @__config = {}
  end
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(*args, &block) ⇒ Object (private) 



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# File 'lib/fedux_org_stdlib/app_config.rb', line 357

def method_missing(*args, &block)
  $stderr.puts "Please check if you have defined an option for #{args.first}."

  super
end

Class Method Details

.known_options ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/fedux_org_stdlib/app_config.rb', line 74

def known_options
  @options ||= Set.new
end

.option(option, default_value) ⇒ Object

Define a writer and a reader for option

Parameters:

  • option (Symbol) —

    Name of option

  • default_value (Object) —

    Default value of option



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# File 'lib/fedux_org_stdlib/app_config.rb', line 143

def option(option, default_value)
  option_reader(option, default_value)
  option_writer(option)
end

.option_reader(option, default_value) ⇒ Object

Define a reader for option

Parameters:

  • option (Symbol) —

    Name of option

  • default_value (Object) —

    The default value of this option



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# File 'lib/fedux_org_stdlib/app_config.rb', line 97

def option_reader(option, default_value)
  option =  option.to_sym

  fail Exceptions::OptionNameForbidden, JSON.dump(option: option) if _reserved_key_words.include? option

  define_method option do
    _config.fetch(option, default_value)
  end

  known_options << option
end

.option_writer(option) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Define a writer for option

Please make sure that you define a reader as well. Otherwise you cannot access the option. Under normal conditions it does not make sense to use this method.

Parameters:

  • option (Symbol) —

    Name of option

Raises:



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# File 'lib/fedux_org_stdlib/app_config.rb', line 122

def option_writer(option)
  fail Exceptions::OptionNameForbidden, JSON.dump(option: option) if _reserved_key_words.include? "#{option}=".to_sym

  define_method "#{option}=".to_sym do |value|
    begin
      _config[option.to_sym] = value
    rescue RuntimeError
      raise Exceptions::ConfigLocked
    end
  end

  known_options << option
end

.process_environment ⇒ Object

Get access to process environment

This might be handy to define default options

Examples:

Get variable


process_environment.fetch('HOME')
# => ENV['HOME']



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# File 'lib/fedux_org_stdlib/app_config.rb', line 86

def process_environment
  @process_environment ||= ProcessEnvironment.new
end

Instance Method Details

#known_options ⇒ Object

Show known options for configuration



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# File 'lib/fedux_org_stdlib/app_config.rb', line 222

def known_options
  self.class.known_options
end

#lock ⇒ Object

Lock the configuration



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# File 'lib/fedux_org_stdlib/app_config.rb', line 227

def lock
  _config.freeze
end

#preferred_configuration_file ⇒ String

Return the path to the preferred configuration file

Returns:

  • (String) —

    The path to the preferred configuration file



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# File 'lib/fedux_org_stdlib/app_config.rb', line 265

def preferred_configuration_file
  _allowed_config_file_paths.first
end

#to_s ⇒ String

Output a string presentation of the configuration

Returns:

  • (String) —

    An formatted version of the configuration



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# File 'lib/fedux_org_stdlib/app_config.rb', line 235

def to_s
  # header 'length' = 6 letters
  length = self.class.known_options.reduce(6) { |a, e| e.size > a ? e.size : a }

  result = []
  result << format("%#{length}s | %s", 'option', 'value')
  result << format('%s + %s', '-' * length, '-' * 80)

  self.class.known_options.each do |o|
    value = public_send(o)

    value = if value == false
              Array(value)
            elsif value.blank?
              Array('is undefined')
            elsif value.is_a?(Hash) || value.is_a?(Array)
              value
            else
              Array(value)
            end

    result << format("%#{length}s | %s", o, value.to_list)
  end

  result.join("\n")
end