Class: Levels::Input::System

Inherits:
Object
  • Object
show all
Defined in:
lib/levels/input/system.rb

Overview

This input creates an env level from the system environment (ENV in ruby). It does so by using an existing level as a template for the group names and values. For each value, it attempts to typecast a String value into the same type found in the template.

Examples

# Given a template level with a single group:
settings: {
  hostname: "example.com",
  workers: 5,
  queues: ["low", "high", "other"]
}

# These environment variables will set new values.
SETTINGS_HOSTNAME=foo.com
SETTINGS_WORKERS=1
SETTINGS_QUEUES=high:low:other

Instance Method Summary collapse

Constructor Details

#initialize(template, key_formatter = nil, env_hash = ENV) ⇒ System

Initialize a new system reader.

template - Enumerator that defines the possible keys. prefix - String prefix for the keys (default: no

prefix).



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# File 'lib/levels/input/system.rb', line 31

def initialize(template, key_formatter = nil, env_hash = ENV)
  @template = template
  @env_hash = env_hash
  @key_formatter = key_formatter || Levels::System::KeyFormatter.new
  @key_parser = Levels::System::KeyParser.new(@key_formatter)
end

Instance Method Details

#read(level) ⇒ Object 



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# File 'lib/levels/input/system.rb', line 38

def read(level)
  @template.each do |group_name, group|
    env_data = {}
    group_data = {}
    group.each do |key, value|
      group_data[key.to_sym] = value
    end
    @env_hash.each do |key, value|
      match_key = @key_formatter.create(group_name, "(.+)")
      matcher = Regexp.new("^#{match_key}$")
      if key =~ matcher
        attr_name = $1.downcase.to_sym
        if group_data.key?(attr_name)
          cast_value = @key_parser.parse(@env_hash, key, group_data[attr_name])
          env_data[attr_name] = cast_value
        end
      end
    end
    if env_data.any?
      level.set_group(group_name, env_data)
    end
  end
end