MF-435 - Add support for env file loading (#1223)

* NO-ISSUE - add support for env file loading

Signed-off-by: Al Hoang <hoanga@gmail.com>

* update go mod

Signed-off-by: Al Hoang <hoanga@gmail.com>

Co-authored-by: Dušan Borovčanin <dusan.borovcanin@mainflux.com>

env.go

@@ -5,6 +5,8 @@ package mainflux
 
 import (
 	"os"
+
+	"github.com/subosito/gotenv"
 )
 
 // Env reads specified environment variable. If no value has been found,
@@ -16,3 +18,9 @@ func Env(key, fallback string) string {
 
 	return fallback
 }
+
+// LoadEnvFile loads environment variables defined in an .env formatted file.
+func LoadEnvFile(envfilepath string) error {
+	err := gotenv.Load(envfilepath)
+	return err
+}

go.mod

@@ -35,6 +35,7 @@ require (
 	github.com/spf13/cobra v1.0.0
 	github.com/spf13/viper v1.7.0
 	github.com/stretchr/testify v1.6.1
+	github.com/subosito/gotenv v1.2.0
 	github.com/uber/jaeger-client-go v2.24.0+incompatible
 	go.mongodb.org/mongo-driver v1.3.5
 	golang.org/x/crypto v0.0.0-20200709230013-948cd5f35899

vendor/modules.txt

@@ -294,6 +294,7 @@ github.com/spf13/viper
 github.com/stretchr/testify/assert
 github.com/stretchr/testify/require
 # github.com/subosito/gotenv v1.2.0
+## explicit
 github.com/subosito/gotenv
 # github.com/uber/jaeger-client-go v2.24.0+incompatible
 ## explicit