goenv

Reflect environment values to config struct

Install

go get github.com/hjhsamuel/goenv

Usage

Support type:

• string
• bool
• int int8 int16 int32 int64
• uint uint8 uint16 uint32 uint64
• float32 float64
• complex64 complex128
• pointer
• struct
• slice
• map

Support tags:

• required
• default
• inline
• -
• name
• lt and lte
• gt and gte

The default config like:

type ServerConfig struct {
	ID          uint            `env:"ID"`
	Port        int             `env:"PORT;gte:1000;lte:60000"`
	MultiServer bool            `env:"MULTISERVER"`
	Peers       map[int]string  `env:"PEERS"`
	IDs         []int           `env:IDS`
}

type LogConfig struct {
	Level string  `env:"LEVEL;default:debug"`
	Path  *string `env:"PATH"`
}

type IPAddress struct {
	IP      string `env:"name:IP"`
	Gateway string `env:"name:GATEWAY"`
}

type IPv4 struct {
	IPAddress   `env:inline`
}

type Config struct {
	ProjectName string        `env:"PROJNAME;required"`
	ProjectID   int64         `env:"PROJID;default:1"`
	Server      *ServerConfig `env:"SERVER"`
	Log         LogConfig     `env:"LOG"`
	Address     IPv4          `env:"name:IPV4"`
}

So, an environment value could be found like ENV_PROJNAME

Some function could be called to set the custom tag:

• SetPrefix or WithPrefix

  the default prefix is ENV

• SetSplitChar or WithSplitChar

  the default split char is _

• SetTag or WithTag

  the default tag name is env

We could parse config struct like:

ENV_PROJNAME=goenv
ENV_SERVER_PEERS="1:127.0.0.1:8000|2:127.0.0.1:8001"
ENV_SERVER_PORT=8000
ENV_SERVER_MULTISERVER=true
ENV_SERVER_IDS="1,2"

c := &Config{ProjectName: "goenv"}
parser := NewEnvParser()
if err := parser.Start(&c); err != nil {
    log.Fatal(err)
}

Custom Unmarshal

You can use your own function to format fields by implement the UnmarshalText interface

type Node struct {
	ID   int
	Addr net.Addr
}

func (n *Node) UnmarshalText(text []byte) error {
	l := bytes.Split(text, []byte("="))
	if len(l) != 2 {
		return errors.New("invalid node format")
	}

	if id, err := strconv.Atoi(string(l[0])); err != nil {
		return err
	} else {
		n.ID = id
	}

	if host, port, err := net.SplitHostPort(string(l[1])); err != nil {
		return err
	} else {
		iport, err := strconv.Atoi(port)
		if err != nil {
			return err
		}
		n.Addr = &net.TCPAddr{IP: net.ParseIP(host), Port: iport}
	}
	return nil
}

type Config struct {
	Node Node `env:"NODE"`
}

ENV_NODE="1=127.0.0.1:8000"