config

Overview ¶

Package config standardizes 12-factor configuration on jessevdk/go-flags: a single options struct whose fields carry `long`/`env`/`default`/`description` tags, so the same definition drives CLI flags, environment variables, and `--help`.

Nested groups use `group`/`namespace`/`env-namespace` tags; the parser uses a "." flag delimiter and a "_" env-namespace delimiter, so a group with env-namespace "DB" and a field with env "USER" reads DB_USER. For local development LoadDotenv seeds the environment from a .env file, but real environment variables always take precedence.

Usage ¶

Define one options struct, parse it, and treat a --help request as a clean exit:

type Config struct {
    Addr string `long:"addr" env:"HTTP_ADDR" default:":8080" description:"listen address"`
    DB   struct {
        User string `long:"user" env:"USER" description:"db user"`
    } `group:"db" namespace:"db" env-namespace:"DB"` // reads DB_USER
}

var cfg Config
if err := config.Parse(&cfg); err != nil {
    if config.IsHelp(err) {
        os.Exit(0)
    }
    log.Fatal(err)
}

After consuming a secret, drop it from the environment so it cannot leak into child processes or crash dumps:

config.Reset("DB_PASSWORD")

API ¶

• Parse(data, dotenvFiles...): load dotenv then parse os.Args into data, dispatching any matched `command:`-tagged subcommand's Execute.
• NewParser(data): a preconfigured *flags.Parser for finer control.
• LoadDotenv(files...): seed env from .env files (default ".env"); missing files are ignored and existing env vars are never overwritten.
• IsHelp(err): reports the benign "help requested" error.
• Reset(keys...): unset environment variables.