use user's home directory when fetching the docker config (#2135)

runtime/docker/auth.go

@@ -11,6 +11,7 @@ import (
 	"github.com/distribution/reference"
 	"github.com/docker/docker/api/types/registry"
 	log "github.com/sirupsen/logrus"
+	"github.com/srl-labs/containerlab/utils"
 )
 
 const (
@@ -44,27 +45,20 @@ func getImageDomainName(imageName string) string {
 	return imageDomainName
 }
 
-func getDockerConfigPath(configPath string) (string, error) {
-	var err error
+func getDockerConfigPath(configPath string) string {
 	if configPath == "" {
-		homeDir, err := os.UserHomeDir()
-		if err != nil {
-			return "", err
-		}
-
-		configPath = filepath.Join(homeDir, dockerDefaultConfigDir, dockerDefaultConfigFile)
+		configPath = utils.ResolvePath(filepath.Join("~", dockerDefaultConfigDir, dockerDefaultConfigFile), "")
 	}
 
-	return configPath, err
+	return configPath
 }
 
+// GetDockerConfig reads the docker config file by the configPath and returns the DockerConfig struct
+// with parts of the docker config.
 func GetDockerConfig(configPath string) (*DockerConfig, error) {
 	var dockerConfig DockerConfig
 
-	dockerConfigPath, err := getDockerConfigPath(configPath)
-	if err != nil {
-		return nil, err
-	}
+	dockerConfigPath := getDockerConfigPath(configPath)
 
 	file, err := os.ReadFile(dockerConfigPath)
 	if err != nil {

runtime/docker/auth_test.go

@@ -60,7 +60,7 @@ func TestGetDockerConfigPath(t *testing.T) {
 	}
 
 	for _, in := range td {
-		got, _ := getDockerConfigPath(in["path"])
+		got := getDockerConfigPath(in["path"])
 		want, _ := homedir.Expand(in["want"])
 		if got != want {
 			t.Errorf("Invalid docker config path, got %v, want %v", got, in["want"])

utils/file.go

@@ -274,6 +274,8 @@ func lookupUserHomeDirViaGetent(userId string) string {
 
 // ResolvePath resolves a string path by expanding `~` to home dir
 // or resolving a relative path by joining it with the base path.
+// When resolving `~` the function uses the home dir of a sudo user, so that -E sudo
+// flag can be omitted.
 func ResolvePath(p, base string) string {
 	if p == "" {
 		return p