Gofig - a simple (but powerful) config library

Gofig is a lightweight and extendable configuration library for Go projects. Originally created for personal use, it has been shared to benefit the community. ❤️

Usage

go get -u github.com/darklam/gofig@v1.2.0

This example demonstrates the main features of Gofig:

package main

import (
	"github.com/darklam/gofig"
	"github.com/darklam/gofig/providers"
)

type PgConfig struct {
	Username string `prop:"username"`
	Password string `prop:"password"`
	Host     string `prop:"host"`
	Port     string `prop:"port"`
}

type Config struct {
	Port      string    `prop:"port" default:"3000"`
	Postgres  *PgConfig `prop:"postgres"`
	RedisHost string    `prop:"redis.host" default:"localhost"`
}

func main() {
	fig := gofig.NewGofig()
	
	json5Provider, err := providers.NewJSONProvider("local.json5")
	if err != nil {
		panic(err)
    }
	
	fig.RegisterProvider(json5Provider)
	
	envProvider := providers.NewEnvProvider()
	
	fig.RegisterProvider(envProvider)
	
	cfg := new(Config)
	
	err = fig.PopulateConfig(cfg)

	if err != nil {
		panic(err)
	}
	
    // The cfg variable now has all the fields populated
}

General information

The v1 version of the library has been improved to support JSON (and JSON5) sources and offer better extensibility.

However, it has also become more opinionated about naming properties in the configuration. This decision helps keep the code simple without sacrificing extendability.

Available tags

• prop: Specifies the name of the property which will be used to fetch its value from the different providers
• default: The default value of the field

You must use at least one of these tags in the struct fields (unless if the field is a struct pointer)

Field types

Gofig supports two field types: string and a pointer to a struct.

If a field is a string, it will be treated as a field to populate.

If a field is a struct pointer, it will be replaced by an instance of the struct with its fields populated according to the tags of its fields.

Fields with no value found will have empty strings. Structs are always instantiated. All fields will be populated recursively.

Provider precedence

The default value has the lowest precedence if set.

The order in which providers are registered determines precedence. For example, if you register providers in this order:

• env
• json

Values fetched from JSON will replace the values from the environment, which in turn will replace the defaults where set.

Adding more providers

Built-in providers include:

• env
• json
• vault

To create custom providers, implement the interfaces/Provider interface in your code (see the interface documentation for more information).

If you think a new provider might be useful, please create a PR.

Vault provider

This allows fetching secrets from HashiCorp Vault.

Options:

• Url: The URL of the vault instance
• RequestTimeout: Specifies the request timeout for the Vault client - default: 0 (no timeout)
• AppRoleAuth: The options for authenticating using an AppRole
• KubernetesAuth: The options for authenticating using Kubernetes
• MountPath: The mountPath of the secret engine
• Path: The path of a secret

At least one of (AppRoleAuth, KubernetesAuth) must be specified.

Example options for path and mountPath:

Suppose there's a KV engine in the path kv/ and a secret named database.

The options would be: mountPath: "kv", path: "database".

The secret values must be strings and the keys will be resolved similarly to the ENV provider (all uppercase and joined with '_')

Testing

You can run:

./run_tests.sh

This script accepts 2 options:

1. -cover - This enables the generation of a coverprofile for the tests
2. -gen - This generates the mocks before running the tests (accomplished by using the generate_mocks.sh script)

Contributing

It's not a popular package to have specific guidelines. If you have issues or want to add extra functionality (hopefully more providers) feel free to open an issue or even better create a PR.

Just be civil and respectful.