Blinkist::Config

This GEM allows you to access configuration stores with different adapters. Here're some examples of usage:

Using the ENV

# First setup the Config to use the ENV as config store

Diplomat.configure do |config|
  config.url = "http://172.17.0.1:8500"
end

Blinkist::Config.env = ENV["RAILS_ENV"]
Blinkist::Config.app_name = "my_nice_app"
Blinkist::Config.adapter_type = :env
Blinkist::Config.error_handler = :strict

my_config_value = Blinkist::Config.get! "some/folder/config"

# This is being translated to ENV["SOME_FOLDER_CONFIG"]

Error handling

When configured with Blinkist::Config.error_handler = :strict (as recommended) reading a configuration entry for which the value is missing (for example missing enviroment variables) will cause Blinkist::Config::ValueMissingError to be raised.

There is also an alternative mode Blinkist::Config.error_handler = :heuristic which will raise exceptions only when Blinkist::Config.env == "production".

This alternative mode is also the default for compatibility.

Having a default value

If you don't want Blinkist::Config.get! to scream at you for missing configuration entries then you canprovide a default value as a second paramter to get!:

my_config_value = Blinkist::Config.get! "some/folder/config", "default value"

# If ENV["SOME_FOLDER_CONFIG"] is nil, "default value" will be returned

Refetching a value

If you want to refetch a value from the config store, you can set the refetch parameter to true. WARNING: This will cut into our SSM quota on AWS - please use this with caution and behind another way of caching. See AWS SSM Quota for more information.

my_config_value = Blinkist::Config.get! "some/folder/config", refetch: true

# This will reload the value from the config store, even if it's cached. The re-fetched value will then be cached.

Using Diplomat & Consul

If you want to use Consul's key value store, simply use our diplomat adapter.

• https://www.consul.io/
• https://github.com/WeAreFarmGeek/diplomat

The GEM expects consul to listen to http://172.17.0.1:8500

# First setup the Config to use the ENV as config store
Blinkist::Config.env = ENV["RAILS_ENV"]
Blinkist::Config.app_name = "my_nice_app"
Blinkist::Config.adapter_type = ENV["CONSUL_AVAILABLE"] == "true" ? :diplomat : :env

my_config_value = Blinkist::Config.get! "some/folder/config"

# This is will try to get a value from Consul's KV store at "my_nice_app/some/folder/config"

Using Diplomat with a folder scope

# Here we setting a scope outside of the app

my_config_value = Blinkist::Config.get! "another/config", scope: "global"

# This will replace `my_nice_app` with `global` and try to resolve "global/another/config"
# With :env the scope will simply be ignored

Using AWS SSM

If you want to use EC2's key value store SSM, simply use our aws_ssm adapter. It'll automatically try to decrypt all keys.

The GEM expects the code to run in an AWS environment with properly set up IAM.

Blinkist::Config.env = ENV["RAILS_ENV"]
Blinkist::Config.app_name = "my_nice_app"
Blinkist::Config.adapter_type = ENV["SSM_AVAILABLE"] == "true" ? :aws_ssm : :env

my_config_value = Blinkist::Config.get! "some/folder/config"

# This is will try to get a parameter from SSM at "/application/my_nice_app/some/folder/config"

# You can also preload all parameters to avoid later calls to SSM
Blinkist::Config.preload
Blinkist::Config.preload scope: "global" # in case you need also another scope being preloaded

Using SSM with a folder scope

# Here we setting a scope outside of the app

my_config_value = Blinkist::Config.get! "another/config", scope: "global"

# This will replace `my_nice_app` with `global` and try to resolve "/application/global/another/config"

Installation

Add this line to your application's Gemfile:

gem "blinkist-config"

Usage

You have to set up the GEM before you can use it. The basic setup requires this

Blinkist::Config.env = "production" || "test" || "development"
Blinkist::Config.app_name = "your_app_name" # Used only with diplomat adapter
Blinkist::Config.adapter_type = :diplomat || :env

It's best to drop a config.rb into your app and load this file before every other file. In Rails you can link it into your application.rb

require_relative "boot"
require_relative "config"

require "rails"
# ...

Development

You can build this project easily with docker compose.

docker compose run rake

This will execute rake and run all specs by auto correcting the code with StandardRB.

If you're ready to tag a new version, do this

docker compose run gem bump -t -v major|minor|patch

To deploy to rubygems.org do this then

docker compose run gem release

You'll have to have proper rights to access rubygems.org

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/blinkist/blinkist-config.

License

The gem is available as open source under the terms of the MIT License.