# Golang Configuration

> Load and validate application configuration from environment variables and config files. Use when managing Go application config with environment variables or viper.

- Skill: `hoangnguyen0403/golang-configuration` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add hoangnguyen0403/golang-configuration`
- Raw SKILL.md: https://api.skillmd.com/api/skills/hoangnguyen0403/golang-configuration/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: HoangNguyen0403 (https://skillmd.com/u/hoangnguyen0403)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/hoangnguyen0403/golang-configuration

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# Golang Configuration

## **Priority: P1 (HIGH)**

## Principles

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

## Implementation Workflow

1. **Define Config struct** — Create typed struct with all required fields.
2. **Load defaults** — Set sensible defaults for non-secret values.
3. **Override from file** — Optionally load from YAML/JSON config file.
4. **Override from env** — Environment variables take highest priority.
5. **Validate at startup** — Crash immediately on missing required config.
6. **Inject via constructor** — Pass Config to services; never use global config vars.

See [config struct and usage examples](references/config-patterns.md)

## Libraries

- **Standard Lib**: `os.Getenv` for simple apps.
- **Viper**: Industry standard for complex configs (env, files, remote).
- **Koanf**: Lighter, cleaner alternative to Viper.
- **Caarlos0/env**: Strict struct tagging approach.

## Anti-Patterns

- **No hardcoded secrets**: load all secrets from env vars or secret manager.
- **No global config vars**: return typed Config struct and inject via constructors.
- **No silent startup**: crash immediately on missing required env vars.

## References

- [Config Pattern](references/config-patterns.md)