support proxy for helm repo validation (#10358)

pkg/libhelm/validate_repo.go

@@ -1,18 +1,15 @@
 package libhelm
 
 import (
+	"errors"
 	"fmt"
 	"net/http"
 	"net/url"
 	"path"
 	"strings"
 	"time"
-
-	"github.com/pkg/errors"
 )
 
-const invalidChartRepo = "%q is not a valid chart repository or cannot be reached"
-
 func ValidateHelmRepositoryURL(repoUrl string, client *http.Client) error {
 	if repoUrl == "" {
 		return errors.New("URL is required")
@@ -20,30 +17,32 @@ func ValidateHelmRepositoryURL(repoUrl string, client *http.Client) error {
 
 	url, err := url.ParseRequestURI(repoUrl)
 	if err != nil {
-		return errors.Wrap(err, fmt.Sprintf("invalid helm chart URL: %s", repoUrl))
+		return fmt.Errorf("invalid helm repository URL '%s': %w", repoUrl, err)
 	}
 
 	if !strings.EqualFold(url.Scheme, "http") && !strings.EqualFold(url.Scheme, "https") {
-		return errors.New(fmt.Sprintf("invalid helm chart URL: %s", repoUrl))
+		return fmt.Errorf("invalid helm repository URL '%s'", repoUrl)
 	}
 
 	url.Path = path.Join(url.Path, "index.yaml")
 
 	if client == nil {
 		client = &http.Client{
-			Timeout: time.Second * 10,
+			Timeout:   time.Second * 10,
+			Transport: http.DefaultTransport,
 		}
 	}
 
+	const invalidChartRepo = "%s is not a valid chart repository or cannot be reached: %w"
 	response, err := client.Head(url.String())
 	if err != nil {
-		return errors.Wrapf(err, invalidChartRepo, repoUrl)
+		return fmt.Errorf(invalidChartRepo, repoUrl, err)
 	}
 
-	// Success is indicated with 2xx status codes
+	// Success is indicated with 2xx status codes. 3xx status codes indicate a redirect.
 	statusOK := response.StatusCode >= 200 && response.StatusCode < 300
 	if !statusOK {
-		return errors.Errorf(invalidChartRepo, repoUrl)
+		return fmt.Errorf(invalidChartRepo, repoUrl, err)
 	}
 
 	return nil