A Ruby gem for working with environment variables much like OptionParser does with command-line arguments.
Install the gem and add to the application's Gemfile by executing:
$ bundle add envp
If bundler is not being used to manage dependencies, install the gem by executing:
$ gem install envp
Envp
allows you to write expectations for environment variables for your program.
Define a program in a new file app.rb
:
reqiure 'envp'
pp Envp.parse do |e|
e.required("FOO")
end
Run the program without any special environment variables:
$ ruby app.rb
app.rb:47:in `handle_errors': FOO: missing required value (Envp::Failure)
from app.rb:26:in `parse'
from -e:1:in `<main>'
Rather then let the program continue with missing required values, an exception is raised immediately.
Run the program with the required environment variables:
$ FOO=bar ruby app.rb
{"FOO"=>"bar"}
The specified environment variables are parsed into a Ruby hash for use in your program.
Environment variables can be coerced from string values into richer types. For example, to parse a value into an integer:
reqiure 'envp'
pp Envp.parse do |e|
e.required("FOO", Integer)
end
Will result in:
$ FOO=123 ruby app.rb
{"FOO"=>123}
Along with various predefined coercions, you can define your own coercions:
reqiure 'envp'
pp Envp.parse do |e|
e.accept(User) do |id|
User.find(id)
end
e.required("USER_ID", User)
end
The following example demonstrates all features:
Envp.parse(constants: true, symbolize: true, normalize: true) do |e|
e.accept(User) do |id|
User.find(id)
end
e.required("USER_ID", User)
e.required("API_KEY", allow_blank: false) do |value|
DEFAULT_LOGGER.debug("using API_KEY #{value}")
end
e.optional("DEBUG", :bool, default: false)
end
# => {:user_id=>#<User...>, :api_key=>"abc123", :debug=>false}
Envp::DEBUG # => false
Envp::API_KEY # => "abc123"
After checking out the repo, run bin/setup
to install dependencies. Then, run rake test
to run the tests. You can also run bin/console
for an interactive prompt that will allow you to experiment.
To install this gem onto your local machine, run bundle exec rake install
. To release a new version, update the version number in version.rb
, and then run bundle exec rake release
, which will create a git tag for the version, push git commits and the created tag, and push the .gem
file to rubygems.org.
Bug reports and pull requests are welcome on GitHub at https://github.com/avdgaag/envp. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.
The gem is available as open source under the terms of the MIT License.
Everyone interacting in the Envp project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.