Revert "fix: remove prefix for searching environment variables"

This reverts commit 7272dd7.

pkg/koanf/config.go

@@ -1,6 +1,7 @@
 package koanf
 
 import (
+	"fmt"
 	"log"
 	"strings"
 
@@ -12,10 +13,14 @@ import (
 )
 
 // New reads configuration with koanf.
-// def contains the default values.
-func Provide[T interface{}](def T) T {
+// service name is used for reading environment variables
+// and def contains the default values.
+func Provide[T interface{}](service string, def T) T {
 	k := koanf.New(".")
 
+	// prefix indicates environment variables prefix.
+	prefix := fmt.Sprintf("%s_", strings.ToUpper(service))
+
 	// create a new instance based-on given time.
 	var instance T
 
@@ -33,8 +38,8 @@ func Provide[T interface{}](def T) T {
 	if err := k.Load(
 		// replace __ with . in environment variables so you can reference field a in struct b
 		// as a__b.
-		env.Provider("", ".", func(source string) string {
-			base := strings.ToLower(source)
+		env.Provider(prefix, ".", func(source string) string {
+			base := strings.ToLower(strings.TrimPrefix(source, prefix))
 
 			return strings.ReplaceAll(base, "__", ".")
 		}),

pkg/koanf/config_test.go

@@ -15,7 +15,7 @@ type Config struct {
 func TestProvideUsingDefault(t *testing.T) {
 	require := require.New(t)
 
-	cfg := koanf.Provide(Config{
+	cfg := koanf.Provide("testing", Config{
 		RabbitMQ: koanf.RabbitMQ{
 			Service:  "rabbitmq.io",
 			Username: "admin",
@@ -28,12 +28,12 @@ func TestProvideUsingDefault(t *testing.T) {
 }
 
 func TestProvideUsingEnv(t *testing.T) {
-	os.Setenv("RABBITMQ__SERVICE", "rabbitmq.com")
-	defer os.Setenv("RABBITMQ__SERVICE", "")
+	os.Setenv("TESTING_RABBITMQ__SERVICE", "rabbitmq.com")
+	defer os.Setenv("TESTING_RABBITMQ__SERVICE", "")
 
 	require := require.New(t)
 
-	cfg := koanf.Provide(Config{
+	cfg := koanf.Provide("testing", Config{
 		RabbitMQ: koanf.RabbitMQ{
 			Service:  "rabbitmq.io",
 			Username: "admin",