config

package main

import (
	"fmt"
	"os"
	"path/filepath"
	"time"

	"github.com/kayac/go-config"
)

var dir string

func main() {
	type DBConfig struct {
		Master  string        `yaml:"master"`
		Slave   string        `yaml:"slave"`
		Timeout time.Duration `yml:"timeout"`
	}
	type Conf struct {
		Domain  string        `yaml:"domain"`
		IsDev   bool          `yaml:"is_dev"`
		Timeout time.Duration `yml:"timeout"`
		DB      DBConfig      `yaml:"db"`
	}

	baseConfig := `
# config.yml
domain: example.com
db:
  master:  rw@/example
  slave:   ro@/example
  timeout: 0.5s
`
	localConfig := `
# config_local.yml
domain: dev.example.com
is_dev: true
`
	conf := &Conf{}
	baseConfigYaml, _ := genConfigFile("config.yml", baseConfig)         // /path/to/config.yml
	localConfigYaml, _ := genConfigFile("config_local.yml", localConfig) // /path/to/config_local.yml

	err := config.Load(conf, baseConfigYaml, localConfigYaml)
	if err != nil {
		panic(err)
	}

	fmt.Printf("%+v", conf)
}

func genConfigFile(name string, config string) (string, error) {
	path := filepath.Join(dir, name)
	io, err := os.Create(path)
	if err != nil {
		return "", err
	}
	if _, err := io.WriteString(config); err != nil {
		return "", err
	}
	return path, nil
}

Output:
&{Domain:dev.example.com IsDev:true Timeout:0s DB:{Master:rw@/example Slave:ro@/example Timeout:500ms}}

package main

import (
	"fmt"
	"os"
	"path/filepath"
	"time"

	"github.com/kayac/go-config"
)

var dir string

func main() {
	type DBConfig struct {
		Master  string        `yaml:"master"`
		Slave   string        `yaml:"slave"`
		Timeout time.Duration `yml:"timeout"`
	}
	type Conf struct {
		Domain  string        `yaml:"domain"`
		IsDev   bool          `yaml:"is_dev"`
		Timeout time.Duration `yml:"timeout"`
		DB      DBConfig      `yaml:"db"`
	}

	baseConfig := `
# config.yml
domain: {{ env "DOMAIN"}}
db:
  master:  rw@/example
  slave:   ro@/example
  timeout: 0.5s
`
	localConfig := `
# config_local.yml
is_dev: true
db:
  master:  {{ env "RW_USER" "rw" }}@/{{ env "DB_NAME" "example_dev" }}
  slave:   {{ env "RO_USER" "ro" }}@/{{ env "DB_NAME" "example_dev" }}
`
	os.Setenv("DOMAIN", "dev.example.com")
	os.Setenv("DB_NAME", "example_local")

	conf := &Conf{}
	baseConfigYaml, _ := genConfigFile("config.yml", baseConfig)         // /path/to/config.yml
	localConfigYaml, _ := genConfigFile("config_local.yml", localConfig) // /path/to/config_local.yml

	err := config.LoadWithEnv(conf, baseConfigYaml, localConfigYaml)
	if err != nil {
		panic(err)
	}

	fmt.Printf("%+v", conf)
}

func genConfigFile(name string, config string) (string, error) {
	path := filepath.Join(dir, name)
	io, err := os.Create(path)
	if err != nil {
		return "", err
	}
	if _, err := io.WriteString(config); err != nil {
		return "", err
	}
	return path, nil
}

Output:
&{Domain:dev.example.com IsDev:true Timeout:0s DB:{Master:rw@/example_local Slave:ro@/example_local Timeout:500ms}}