CODEWITHSUNDEEP
ruby-on-railsruby
Doublespeed
Doublespeed

Reputation: 1173

configuration file for a standalone ruby script

I have a ruby script that runs on a linux server. Its not using rails or anything. Its basically a commandline ruby script that can be passed arguments like this: ./ruby_script.rb arg1 arg2

How can I abstract away the arguments into a configuration file such as a yaml file or something? Can you provide an example of how this can be done?

Thank you in advance.

Upvotes: 5

Views: 8082

Answers (3)

kaybee99
kaybee99

Reputation: 4734

I encountered an undefined local variable or method error when reading from the YAML file using the method in the accepted answer. I did it in a slightly different way:

Write to it as above:

require "yaml"
File.write("path/to/yaml", ["test_arg_1", "test_arg_2"].to_yaml)

Read from using a slight variation:

require "yaml"
arg1, arg2 = YAML.load(File.read("path/to/yaml"))

puts arg1
#=> test_arg_1
puts arg2
#=> test_arg_2

Upvotes: 0

Rory O'Kane
Rory O'Kane

Reputation: 30388

You can use the system I wrote as part of neomind-dashboard-public, a standalone Ruby script under the open-source MIT License.

Your project’s config folder should contain a config.yml file with your configuration data, like this:

updater script:
  code URL: https://github.com/NeomindLabs/neomind-dashboard-public

Leftronic dashboard:
  dashboard access key: 'bGVmdHJvbmljaXNhd2Vz' # find on https://www.leftronic.com/api/
  stream names:

    statuses for CI project names:
      "Project Alpha": project_alpha_ci_status
      "Project Beta": project_beta_ci_status
      "Project Gamma": project_gamma_ci_status
# etc.

Copy the file lib/config_loader.rb to your project. It’s a very small file that uses the built-in yaml library to load the YAML config file.

# encoding: utf-8

require 'yaml'

class ConfigLoader
  def initialize
    load_config_data
  end

  def [](name)
    config_for(name)
  end

  def config_for(name)
    @config_data[name]
  end

  private

  def load_config_data
    config_file_path = 'config/config.yml'
    begin
      config_file_contents = File.read(config_file_path)
    rescue Errno::ENOENT
      $stderr.puts "missing config file"
      raise
    end
    @config_data = YAML.load(config_file_contents)
  end
end

Finally, in each file that uses the config file, follow this pattern (this example comes from the file lib/dashboard_updater.rb):

require the library

require_relative 'config_loader'

load CONFIG constant with your first-level key in the config file

class DashboardUpdater
  CONFIG = ConfigLoader.new.config_for("Leftronic dashboard")

use CONFIG to read configuration data

  def initialize_updater
    access_key = CONFIG["dashboard access key"]
    @updater = Leftronic.new(access_key)
  end

Upvotes: 3

sawa
sawa

Reputation: 168071

First, you can run an independent script that writes to a YAML configuration file:

require "yaml"
File.write("path_to_yaml_file", [arg1, arg2].to_yaml)

Then, read it within your app:

require "yaml"
arg1, arg2 = YAML.load_file("path_to_yaml")
# use arg1, arg2
...

Upvotes: 8

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