nagyistge / go-env Goto Github PK

See the Godoc for usage.

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 testEnv struct {
	RequiredString string `env:"REQUIRED_STRING,required"`
	OptionalString string `env:"OPTIONAL_STRING"`
	OptionalInt    int    `env:"OPTIONAL_INT"`
	OptionalBool   bool   `env:"OPTIONAL_BOOL"`
	OptionalStruct struct {
		StructOptionalInt int `env:"STRUCT_OPTIONAL_INT"`
	} `env:"OPTIONAL_STRUCT,match=FOO"`
	OptionalStructTwo struct {
		StructOptionalInt int `env:"STRUCT_OPTIONAL_INT"`
	} `env:"OPTIONAL_STRUCT_TWO,match=^(FOO|BAR)$"`
}

To populate this, would would call:

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

Non-struct fields have the name of the environment variable, optionally followed by a "required" option, which will throw an error if the environment variable is not set. Struct fields have the name of an environment variable, (not) optionally followed at a "match=REGEX" option, which says that if the value of the environment variable matches the regex, set the fields within the struct. This is useful for situations such as:

type env struct {
	QueueType string `env:"QUEUE_TYPE,required"`
	Sqs struct {
		AwsRegion string `env:"AWS_REGION,required"`
	} `env:"QUEUE_TYPE,match=^SQS$"`
	Redis struct {
		DatabaseURL string `env:"DATABASE_URL,required"`
	} `env:"QUEUE_TYPE,match=^REDIS$"`
}

PopulateOptions has two fields:

• RestrictTo: this is a list of all allowed environment variables on structs. This is useful if you have a bunch of mini-services within a repo, and you want to record all variables that are used across your services in one comment place in code.
• Decoders: you can set additional Decoders (both an env file decoder and a JSON decoder are provided) to provider additional environment variables on top of those set at the system level. Decoders overwrite system level values, and Decoders later in the slice override those earlier in the slice.