golang-configuration

name	golang-configuration
description	Standards for application configuration using environment variables and libraries. Use when managing Go application config with environment variables or viper. (triggers: configs/**, cmd/**, configuration, env var, viper, koanf)

Golang Configuration Standards

Priority: P1 (STANDARD)

Principles

• 12-Factor App: Store config in environment variables.
• Typed Config: Load config into a struct, validate it immediately.
• Secrets: Never commit secrets. Use env vars or secret managers.
• No Globals: Return a Config struct and inject it.

Libraries

• Standard Lib: os.Getenv for simple apps.
• Viper: Industry standard for complex configs (supports env, config files, remote config).
• Koanf: Lighter, cleaner alternative to Viper.
• Caarlos0/env: Good for strict struct tagging.

Pattern

1. Define Config struct.
2. Load from defaults.
3. Override from file (optional).
4. Override from Env (priority).
5. Validate.

References

• Config Pattern

Anti-Patterns

• No hardcoded secrets: Load all secrets from env vars or a secret manager.
• No global config vars: Return a typed Config struct and inject it via constructors.
• No startup without validation: Crash immediately on missing required env vars.