Compadre

Compadre is a lightweight Go package for application configuration using JSON. It provides a thin layer over encoding/json allowing you to interpolate environment variables with default values.

Installation

Get it

go get github.com/KevinSjoberg/compadre

Include it

import "github.com/KevinSjoberg/compadre"

Usage

Define your application settings:

{
  "app": {
    "port": 3000
  },
  "database": {
    "timeout": {{ i "DB_TIMEOUT:1000" }},
    "connectionString": {{ "dbname=testdb sslmode=%s" | s "DB_SSL:true" }}
  }
}

Describe your configuration object using structs:

type Config struct {
	App      AppConfig
	Database DatabaseConfig
}

type AppConfig struct {
	Port int
}

type DatabaseConfig struct {
	Timeout          int
	ConnectionString string
}

Sit back and let Compadre handle the rest for you:

func main() {
	var config Config
	if err := compadre.Read("config.json", &config); err != nil {
		log.Fatalf("Failed to read configuration file: %s\n", err)
	}

	fmt.Println(config.App.Port)                  // => 3000
	fmt.Println(config.Database.Timeout)          // => 1000
	fmt.Println(config.Database.ConnectionString) // => "dbname=testdb sslmode=true"
}

Details

Compadre empowers your standard JSON file by allowing you to define expressions that expand during runtime. Expressions are defined as in the text/template package.