Blinkist::Config

Read configuration values through one interface, backed by the store you pick: the process ENV, AWS SSM Parameter Store, Consul (via Diplomat), or ENV with an SSM fallback.

gem "blinkist-config"

Configure the gem once, before anything else loads. In Rails, put this in a config.rb and require it from application.rb right after boot.

Blinkist::Config.env = ENV["RAILS_ENV"]
Blinkist::Config.app_name = "my_nice_app"
Blinkist::Config.adapter_type = :env # :env, :aws_ssm, :env_over_ssm or :diplomat
Blinkist::Config.error_handler = :strict

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

With :env this reads ENV["SOME_FOLDER_CONFIG"]. With :aws_ssm it reads /application/my_nice_app/some/folder/config. With :diplomat it reads my_nice_app/some/folder/config.

Pass a default as the second argument. Then a missing value returns the default instead of raising.

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

A scope replaces the app name in the key path. The :env adapter ignores it.

Blinkist::Config.get! "another/config", scope: "global"
# aws_ssm: /application/global/another/config
# diplomat: global/another/config

Values are cached after the first read. Pass refetch: true to read from the store again. This costs SSM quota, so use it with care.

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

• :strict raises Blinkist::Config::ValueMissingError when a value is missing. Recommended.
• :heuristic raises only when env == "production". This is the default for backwards compatibility.

Reads from ENV. The key is upcased and / becomes _.

Reads from AWS SSM Parameter Store with decryption. The code must run with IAM access to the parameters.

Blinkist::Config.adapter_type = :aws_ssm

# Load all parameters of a scope in one call to avoid later lookups
Blinkist::Config.preload
Blinkist::Config.preload scope: "global"

Reads from ENV first. When the ENV has no value, it falls back to SSM. This lets you override single SSM values locally or in CI without touching the parameter store.

Blinkist::Config.adapter_type = :env_over_ssm

Blinkist::Config.get! "database/url"
# 1. ENV["DATABASE_URL"] if set
# 2. otherwise /application/my_nice_app/database/url from SSM

scope, refetch and preload apply to the SSM part only.

Reads from Consul's key value store through Diplomat. Configure Diplomat yourself before use.

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

Blinkist::Config.adapter_type = :diplomat

Requires Task and Docker.

task bundle       # install gems for all supported Ruby versions
task test         # run specs on all supported Ruby versions
task test:local   # run specs on the default Ruby version
task test:3.4     # run specs on one Ruby version
task lint         # run StandardRB
task shell        # open a shell in the container

1. Bump VERSION in lib/blinkist/config/version.rb. The version-guard workflow fails a PR to main without a bump.
2. Merge to main.

MIT, see LICENSE.