What is the difference between Application.get_env and Application.fetch_env!?

Application.get_env/3 provides a fallback default value if a configuration is missing. Application.fetch_env!/2 raises an ArgumentError if the key is missing, making it the preferred choice for mandatory production secrets.

When should I use runtime.exs instead of config.exs?

Use runtime.exs for any values that need to be determined at application startup, such as environment variables, secrets, or system ports. Use config.exs only for values that must be known during the compilation phase.

Why shouldn't I use Mix.env() in production code?

The Mix module is a build tool that is not included in production releases (compiled beam files). Using Mix.env() in application code will cause the application to crash in a production environment.

How do I handle configuration for Elixir libraries?

Libraries should generally avoid reading from the Application environment directly. Instead, they should accept options as arguments in their function calls, allowing the parent application to decide how to provide those values.

Elixir Application Configuration

Name: Elixir Application Configuration
Author: vinnie357

byvinnie357

デプロイメントとDevOps

Implements Elixir configuration best practices using runtime and compile-time patterns for robust application deployments.

概要

The Elixir Configuration skill provides a comprehensive framework for managing application settings across development, testing, and production environments. It emphasizes the critical distinction between compile-time (config.exs) and runtime (runtime.exs) configuration, ensuring that developers correctly handle environment variables, secrets, and system-level defaults. By applying these standardized patterns, developers can avoid common pitfalls like environment variable leaks during compilation and ensure their Elixir releases are portable and production-ready.

主な機能

Expert guidance on runtime vs compile-time configuration strategy
Standardized patterns for Application.get_env and Application.fetch_env! usage
0 GitHub stars
Anti-pattern detection for library configuration and Mix module usage
Migration pathways from legacy Mix.Config to modern import Config
Best practices for environment variable integration via System.get_env

ユースケース

Refactoring legacy Elixir applications to utilize modern runtime.exs patterns
Designing configurable Elixir libraries that follow ecosystem best practices
Setting up environment-aware configurations for Elixir releases and Docker containers

概要

主な機能

Expert guidance on runtime vs compile-time configuration strategy
Standardized patterns for Application.get_env and Application.fetch_env! usage
0 GitHub stars
Anti-pattern detection for library configuration and Mix module usage
Migration pathways from legacy Mix.Config to modern import Config
Best practices for environment variable integration via System.get_env

ユースケース

Refactoring legacy Elixir applications to utilize modern runtime.exs patterns
Designing configurable Elixir libraries that follow ecosystem best practices
Setting up environment-aware configurations for Elixir releases and Docker containers