This library is made up of two parts :
- Env object : it wraps your environments variables in an object and provides convenient helpers.
- Env tree object : it manages environment variables through a tree structure to store a config the same way as in a yaml file or whatever format allows to store a config hierarchically
go get github.com/antham/envh
Check the godoc, there are many examples provided.
package envh
import (
"encoding/json"
"fmt"
"os"
"strings"
)
type CONFIG2 struct {
DB struct {
USERNAME string
PASSWORD string
HOST string
NAME string
PORT int
URL string
USAGELIMIT float32
}
MAILER struct {
HOST string
USERNAME string
PASSWORD string
ENABLED bool
}
MAP map[string]string
}
func (c *CONFIG2) Walk(tree *EnvTree, keyChain []string) (bool, error) {
if setter, ok := map[string]func(*EnvTree, []string) error{
"CONFIG2_DB_URL": c.setURL,
"CONFIG2_MAP": c.setMap,
}[strings.Join(keyChain, "_")]; ok {
return true, setter(tree, keyChain)
}
return false, nil
}
func (c *CONFIG2) setMap(tree *EnvTree, keyChain []string) error {
datas := map[string]string{}
keys, err := tree.FindChildrenKeys(keyChain...)
if err != nil {
return err
}
for _, key := range keys {
value, err := tree.FindString(append(keyChain, key)...)
if err != nil {
return err
}
datas[key] = value
}
c.MAP = datas
return nil
}
func (c *CONFIG2) setURL(tree *EnvTree, keyChain []string) error {
datas := map[string]string{}
for _, key := range []string{"USERNAME", "PASSWORD", "HOST", "NAME"} {
value, err := tree.FindString("CONFIG2", "DB", key)
if err != nil {
return err
}
datas[key] = value
}
port, err := tree.FindInt("CONFIG2", "DB", "PORT")
if err != nil {
return err
}
c.DB.URL = fmt.Sprintf("jdbc:mysql://%s:%d/%s?user=%s&password=%s", datas["HOST"], port, datas["NAME"], datas["USERNAME"], datas["PASSWORD"])
return nil
}
func ExampleStructWalker_customFieldSet() {
os.Clearenv()
setEnv("CONFIG2_DB_USERNAME", "foo")
setEnv("CONFIG2_DB_PASSWORD", "bar")
setEnv("CONFIG2_DB_HOST", "localhost")
setEnv("CONFIG2_DB_NAME", "my-db")
setEnv("CONFIG2_DB_PORT", "3306")
setEnv("CONFIG2_DB_USAGELIMIT", "95.6")
setEnv("CONFIG2_MAILER_HOST", "127.0.0.1")
setEnv("CONFIG2_MAILER_USERNAME", "foo")
setEnv("CONFIG2_MAILER_PASSWORD", "bar")
setEnv("CONFIG2_MAILER_ENABLED", "true")
setEnv("CONFIG2_MAP_KEY1", "value1")
setEnv("CONFIG2_MAP_KEY2", "value2")
setEnv("CONFIG2_MAP_KEY3", "value3")
env, err := NewEnvTree("^CONFIG2", "_")
if err != nil {
return
}
s := CONFIG2{}
err = env.PopulateStruct(&s)
if err != nil {
return
}
b, err := json.Marshal(s)
if err != nil {
return
}
fmt.Println(string(b))
// Output:
// {"DB":{"USERNAME":"foo","PASSWORD":"bar","HOST":"localhost","NAME":"my-db","PORT":3306,"URL":"jdbc:mysql://localhost:3306/my-db?user=foo\u0026password=bar","USAGELIMIT":95.6},"MAILER":{"HOST":"127.0.0.1","USERNAME":"foo","PASSWORD":"bar","ENABLED":true},"MAP":{"KEY1":"value1","KEY2":"value2","KEY3":"value3"}}
}