Cong

Golang library for convenient configuration management

The library inside uses viper

Provides the ability to use a pre-configured viper through a simplified initialization interface.
Additionally able to map CamelCase structure fields to SnakeCase environment variables. Example: field ServerName is going to be mapped with environment variable SERVER_NAME,in the original viper work differently - field ServerName is going to be mapped with environment variable SERVERNAME.

The interface has 4 loader methods, the choice depends on how you plan to load configuration files:

1. Load(projectName string, ext ConfigExtension, configPaths ...string) (*T, error) - downloads a single file by project name and extension. The file is searched in directories by the passed paths or in default directories (".", "./config", "./static"). The directory search is sequential, only the first found file will be loaded. Loader reads the config file and unmarshal it into an generic type object, the object is returned for further use.
2. LoadFromDir(projectName string, path string, ext ConfigExtension) (*T, error) - all files from the directory with the passed extension are loaded and unmarshal.
3. LoadFromEmbedFS(projectName string, dir embed.FS, ext ConfigExtension) (*T, error)-all files from the embed.FS with the passed extension are loaded and unmarshal.
4. LoadFromEmbedFSByPath(projectName string, dir embed.FS, path string, ext ConfigExtension) (*T, error)-all files by path from the embed.FS with the passed extension are loaded and unmarshal.

Examples

JSON

{
  "port": 80,
  "timeout": "10s"
}

package main

import (
	"encoding/json"
	"fmt"
	"github.com/kolobok-kelbek/cong"
)

type Config struct {
	Port    int
	Timeout string
}

func main() {
	loader := cong.NewLoader[Config]()
	data, err := loader.Load("config", cong.JsonExt)
	if err != nil {
		panic(err)
	}

	marshal, err := json.Marshal(data)
	if err != nil {
		panic(fmt.Errorf("fatal error marshal config data: %w", err))
	}

	fmt.Println(string(marshal))
}

YAML

serverName: HelloWorld
port: 80
timeout: 20

package main

import (
	"encoding/json"
	"fmt"
	"github.com/kolobok-kelbek/cong"
)

type Config struct {
	ServerName string `mapstructure:"serverName"`
	Port       int    `mapstructure:"port"`
	Timeout    string `mapstructure:"timeout"`
}

func main() {
	loader := cong.NewLoader[Config]()
	data, err := loader.Load("config", cong.YamlExt)
	if err != nil {
		panic(err)
	}

	marshal, err := json.Marshal(data)
	if err != nil {
		panic(fmt.Errorf("fatal error marshal config data: %w", err))
	}

	fmt.Println(string(marshal))
}

YAML and binding environment variables

serverName: HelloWorld
port: 80
timeout: 20

package main

import (
	"encoding/json"
	"fmt"
	"github.com/kolobok-kelbek/cong"
	"os"
)

type Config struct {
	ServerName string `mapstructure:"serverName"`
	Port       int    `mapstructure:"port"`
	Timeout    string `mapstructure:"timeout"`
}

func main() {
	os.Setenv("CONFIG_SERVER_NAME", "pam-pam")

	loader := cong.NewLoader[Config]()
	data, err := loader.Load("config", cong.YamlExt)
	if err != nil {
		panic(err)
	}

	marshal, err := json.Marshal(data)
	if err != nil {
		panic(fmt.Errorf("fatal error marshal config data: %w", err))
	}

	fmt.Println(string(marshal))
}

More examples you can find in loader_test.go