Anyway Config Coder

Never use ENV directly or Rails credentials. Wrap all configuration in typed anyway_config classes.

WRONG

api_key = ENV["GEMINI_API_KEY"]

RIGHT

class GeminiConfig < Anyway::Config attr_config :api_key, timeout: 30 required :api_key end GeminiConfig.new.api_key

Configuration Class Pattern

config/configs/gemini_config.rb

class GeminiConfig < Anyway::Config attr_config :api_key, model: "gemini-pro", timeout: 30, max_retries: 3 required :api_key

def configured? = api_key.present? end

ENV auto-mapping: GeminiConfig -> GEMINI_API_KEY , GEMINI_MODEL , etc. Override prefix with config_name :payment .

Nested config uses hash defaults, accessed via dot notation: AppConfig.new.database.host .

Singleton Pattern (Recommended)

class GeminiConfig < Anyway::Config attr_config :api_key, :model

class << self def instance = @instance ||= new end end

GeminiConfig.instance.api_key

Directory Structure

config/ ├── configs/ # Ruby config classes │ ├── gemini_config.rb │ └── stripe_config.rb └── settings/ # YAML overrides (optional) └── gemini.yml

YAML files use default: &default with environment-specific overrides (development: , test: , production: ).

Validation

class StorageConfig < Anyway::Config attr_config :bucket, :region, :access_key_id, :secret_access_key required :bucket, :region required :access_key_id, :secret_access_key, env: :production # Conditional

def validate! super raise_validation_error("Invalid region") unless %w[us-east-1 us-west-2 eu-west-1].include?(region) end end

Type Coercion

class ApiConfig < Anyway::Config

Automatic coercion

attr_config timeout: 30 # Integer attr_config enabled: true # Boolean attr_config rate: 1.5 # Float

Coerce arrays from comma-separated strings

coerce_types allowed_origins: { type: :string, array: true }

ALLOWED_ORIGINS="example.com,other.com" => ["example.com", "other.com"]

end

Testing Configurations

Test defaults, required validations, and computed methods. Override in tests with with_env :

RSpec.describe GeminiConfig do it "requires api_key" do expect { described_class.new(api_key: nil) }.to raise_error(Anyway::Config::ValidationError) end end

spec/support/anyway_config.rb - global override

RSpec.configure do |config| config.around(:each) do |example| with_env("GEMINI_API_KEY" => "test-key") { example.run } end end

Common Patterns

API Client Config

Add client_options helper to build connection hashes:

class OpenAIConfig < Anyway::Config attr_config :api_key, :organization_id, model: "gpt-4", max_tokens: 1000 required :api_key

def client_options = { access_token: api_key, organization_id: }.compact end

Multi-Provider Config

Use predicate methods and case for provider-specific options:

class StorageConfig < Anyway::Config attr_config provider: "local", bucket: nil, endpoint: nil

def s3? = provider == "s3" def local? = provider == "local" def service_options = case provider when "s3" then s3_options else local_options end end

Anti-Patterns

Anti-Pattern Problem Solution

Direct ENV["KEY"]

No type safety, scattered Config class

ENV.fetch everywhere Duplication, no validation Centralized config

Rails credentials Complex, hard to test anyway_config classes

Hardcoded secrets Security risk Environment variables

Magic strings Typos, no IDE support Config constants

Detailed References

• references/advanced-patterns.md
• Dynamic configs, callbacks, inheritance