config: don't call homedir on init()

This patch changes the package to lazily obtain the user's home-
directory on first use, instead of when initializing the package.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit 8a30653ed5276179cc4dc0978af13ea2068c7d4e)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Upstream-commit: 8434242c743c051a56381c280eeec7518a9662dd
Component: cli

Author: thaJeztah

components/cli/cli/config/config.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
 
 	"github.com/docker/cli/cli/config/configfile"
 	"github.com/docker/cli/cli/config/credentials"
@@ -23,17 +24,23 @@ const (
 )
 
 var (
-	configDir = os.Getenv("DOCKER_CONFIG")
+	initConfigDir sync.Once
+	configDir     string
 )
 
-func init() {
+func setConfigDir() {
+	if configDir != "" {
+		return
+	}
+	configDir = os.Getenv("DOCKER_CONFIG")
 	if configDir == "" {
 		configDir = filepath.Join(homedir.Get(), configFileDir)
 	}
 }
 
 // Dir returns the directory the configuration file is stored in
 func Dir() string {
+	initConfigDir.Do(setConfigDir)
 	return configDir
 }