Add viper bind env func

Author: dsxack

go.mod

@@ -1,3 +1,10 @@
 module github.com/dsxack/go/v2
 
 go 1.13
+
+require (
+	github.com/go-kit/kit v0.10.0
+	github.com/sirupsen/logrus v1.6.0
+	github.com/spf13/viper v1.7.1
+	github.com/stretchr/testify v1.6.1
+)

kit/go.sum go.sumkit/go.sum renamed to go.sum

@@ -2,7 +2,7 @@ package formatter_test
 
 import (
 	"bytes"
-	_logrus "github.com/dsxack/go/logrus/formatter"
+	_logrus "github.com/dsxack/go/v2/logrus/formatter"
 	"github.com/sirupsen/logrus"
 	"github.com/stretchr/testify/assert"
 	"testing"

kit/go.mod

@@ -0,0 +1,35 @@
+package viper
+
+import (
+	"github.com/spf13/viper"
+	"reflect"
+	"strings"
+)
+
+func BindEnvs(v *viper.Viper, iface interface{}, parts ...string) error {
+	ifv := reflect.ValueOf(iface)
+	ift := reflect.TypeOf(iface)
+	for i := 0; i < ift.NumField(); i++ {
+		fieldv := ifv.Field(i)
+		t := ift.Field(i)
+		name := strings.ToLower(t.Name)
+		tag, ok := t.Tag.Lookup("mapstructure")
+		if ok {
+			name = tag
+		}
+		path := append(parts, name)
+		switch fieldv.Kind() {
+		case reflect.Struct:
+			err := BindEnvs(v, fieldv.Interface(), path...)
+			if err != nil {
+				return err
+			}
+		default:
+			err := v.BindEnv(strings.Join(path, "."))
+			if err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}