Package env handles environment variables in a structured manner. It uses reflection to set fields on a struct pointer passed to the main public method, Populate.

Example (from the test):

type subEnv struct {
	SubEnvRequiredString        string `env:"SUB_ENV_REQUIRED_STRING,required"`
	SubEnvOptionalString        string `env:"SUB_ENV_OPTIONAL_STRING"`
	SubEnvOptionalUint16Default uint16 `env:"SUB_ENV_OPTIONAL_UINT16_DEFAULT,default=1024"`
}

type testEnv struct {
	RequiredString string `env:"REQUIRED_STRING,required"`
	OptionalString string `env:"OPTIONAL_STRING"`
	OptionalInt    int    `env:"OPTIONAL_INT"`
	OptionalBool   bool   `env:"OPTIONAL_BOOL"`
	SubEnv         subEnv
	Struct         struct {
		StructOptionalInt int `env:"STRUCT_OPTIONAL_INT"`
	}
	OptionalStringDefault string `env:"OPTIONAL_STRING_DEFAULT,default=foo"`
}

To populate this, one would call:

testEnv := &testEnv{}
if err := env.Populate(testEnv); err != nil {
	return err
}