Bindan

Bindan is a Ruby gem for building single configuration object from various sources with providers (that is bundled Google Cloud Storage and Firestore platform by default). It provides a flexible way to manage application settings, supporting lazy initialization and seamless switching between development (using emulators) and production (eg. actual GCP services) environments.

• Environment Transparency: Use the same code for development (with emulators) and production.
• Multiple Providers: Fetch configuration from:
  • Environment Variables
  • Google Cloud Storage
  • Google Cloud Firestore
  • your custom provider

Add this line to your application's Gemfile:

gem 'bindan'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install bindan

Here is a basic example of how to use Bindan.

Envvar built-in provider does not need extra code.

require "bindan"

config = Bindan.configure do |c, pr|
  c.database_host = pr.env["DATABASE_HOST"] || "localhost"
end

# unless $DATABASE_HOST environment variable
puts config.database_host # => "localhost"

or

require "bindan"

class App
  extend Bindan
end

App.configure do |c, pr|
  c.database_host = pr.env["DATABASE_HOST"] || "localhost"
end

# unless $DATABASE_HOST environment variable
puts App.config.database_host # => "localhost"

in Gemfile

gem "bindan"
gem "google-cloud-storage"
gem "google-cloud-firestore"

and

require "bindan"
require "google/client/storage"
require "google/client/firestore"

# Define your configuration providers
providers = {
  env: Bindan::Provider::Envvar.new,
  storage: Bindan::Provider::Storage.new(bucket: "my-config-bucket"),
  firestore: Bindan::Provider::Firestore.new(collection: "app-settings")
}

# Configure Bindan
config = Bindan.configure(providers: providers) do |c, pr|
  # Define configuration keys and how they are loaded from providers and fallback
  c.database_host = pr.env["DATABASE_HOST"] || "localhost"
  c.api_key = pr.storage["api_key"]
  c.feature_flags = pr.firestore["feature_flags_document"]
end

# Access your configuration values
puts config.database_host # => "localhost" (or value from ENV["DATABASE_HOST"])
puts config.api_key       # => (Value loaded from Google Cloud Storage)
puts config.feature_flags # => (Value loaded from Firestore)

In the configure block, you define how each configuration key is mapped to a provider. The provider name is providers Hash key.

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

This gem is designed to interacts with Google Cloud services as a first-class citizen. For local development and testing, it uses emulators. Please install the following tools:

1. Google Cloud CLI: Installation the gcloud CLI
2. Docker: Get Docker
3. Firestore Emulator:

   gcloud components install cloud-firestore-emulator

4. fake-gcs-server:

   docker pull fsouza/fake-gcs-server

implement [] method.

class CustomProvider
  def [](key)
    ...
  end
end

The test suite is configured to automatically start the emulators (including fake-gcs-server via Docker), run the tests against them, and shut them down. Simply run:

bundle exec rake spec

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/wtnabe/bindan.