Example

A very basic example (check the examples folder):

package main

import (
	"fmt"
	"time"
	
	"github.com/neliseev/go-config"
)

type params struct {
	Home         string        `env:"HOME"`
	Port         int           `env:"PORT" envDefault:"3000"`
	IsProduction bool          `env:"PRODUCTION"`
	Hosts        []string      `env:"HOSTS" envSeparator:":"`
	Duration     time.Duration `env:"DURATION"`
}

func main() {
	p := new(params)
	if err := config.Parse(nil, p); err != nil {
		fmt.Printf("%+v\n", err)
	}
	
	fmt.Printf("%+v\n", p)
}

You can run it like this:

$ PRODUCTION=true HOSTS="host1:host2:host3" DURATION=1s go run examples/first.go
{Home:/your/home Port:3000 IsProduction:true Hosts:[host1 host2 host3] Duration:1s}

Supported types and defaults for ENV

The library has support for the following types:

• string
• int
• int64
• bool
• float32
• float64
• []string
• []int
• []bool
• []float32
• []float64

If you set the envDefault tag for something, this value will be used in the case of absence of it in the environment. If you don't do that AND the environment variable is also not set, the zero-value of the type will be used: empty for strings, false for bools and 0 for ints.

By default, slice types will split the environment value on ,; you can change this behavior by setting the envSeparator tag.

Also u can provide []byte with json/yaml file, ordering for build config that: first parse config file and after ENV, so config will merged.

Required fields

The env tag option required (e.g., env:"tagKey,required") can be added to ensure that some environment variable is set. In the example above, an error is returned if the config struct is changed to:

type config struct {
    Home         string   `yaml:"home" env:"HOME"`
    Port         int      `json:"port" env:"PORT" envDefault:"3000"`
    IsProduction bool     `env:"PRODUCTION"`
    Hosts        []string `env:"HOSTS" envSeparator:":"`
    SecretKey    string   `env:"SECRET_KEY,required"`
}