Configuration

Application Configuration

Arrower uses viper for configuration. So you can be flexible in how you set up your app to build and ship what you want.

Arrower ships with its own config that has everything to get you started with an empty project.

In the most cases you want to roll your own config, to support exactly what you need. It is seamless to extend the Arrower config to your needs:

shared/infrastructure/config/config.go

type MyConfig struct {
	arrower.Config `mapstructure:",squash"`
	YourKey        string `mapstructure:"your-key"`
}

func Load(cfgFile string) (*Config, error) {
  vip := arrower.DefaultViper()

  // Priority 2: default values
  vip.SetDefault("", nil)
  // Priority 1: config file values
  vip.SetConfigFile(cfgFile)
  // Priority 0: environment variables values
  vip.SetEnvPrefix("YourAppsName")
  
  // ...
  
  config := Config{}

  err := vip.Unmarshal(&config)
  
  return &config, nil
}

This is an example of a Arrower configuration file. Add your own configuration according to your needs.

Familiarise yourself with viper's precedence order. In the following example of a configuration file for the test environment, only the required keys are set, and other keys fall back to the configured defaults.

.config/your-config_test.config.yaml

environment: test

postgres:
  user: arrower
  password: secret
  database: arrower_test
  host: localhost
  port: 5432
  sslmode: disable
  max_conns: 10

your-key: your-value

Secrets

Arrower provides a secret.Secret type to prevent sensitive values from being accidentally exposed in logs, JSON output, or string representations.

s := secret.New("my-cookie-secret")

s.String()          // "******"
s.Secret()          // "my-cookie-secret" - access the actual value

Use it in your config struct for fields that should never appear in logs or API responses:

type MyConfig struct {
    arrower.Config `mapstructure:",squash"`
    APIKey         secret.Secret `mapstructure:"api_key"`
}

The Secret type implements:

• fmt.Stringer - always returns ******
• json.Marshaler / json.Unmarshaler - masks on marshal, unmarshals the real value
• encoding.TextMarshaler / encoding.TextUnmarshaler - masks on marshal
• sql.Scanner / driver.Valuer - persists the real value to the database
• slog integration - logged values show ******

note

The value is obfuscated, not encrypted. It can still be accessed via unsafe.Pointer. For stronger guarantees, encrypt the data before storing it.