Remove discovery RestClient usage

pkg/auth/token_handler.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"io"
 	"net/http"
 	"time"
 
@@ -101,17 +102,21 @@ func (c *OIDCTokenHandler) getHTTPClientForKubeAPIServer() (*http.Client, error)
 }
 
 func (c *OIDCTokenHandler) getKubernetesOIDCConfiguration(ctx context.Context) (*openIDMetadata, error) {
-	req := c.kubeClient.Discovery().RESTClient().Get().RequestURI("/.well-known/openid-configuration")
-
-	res := req.Do(ctx)
-	if err := res.Error(); err != nil {
-		return nil, fmt.Errorf("could not execute request: %w", err)
+	client, err := c.getHTTPClientForKubeAPIServer()
+	if err != nil {
+		return nil, fmt.Errorf("could not get HTTP client for API server: %w", err)
 	}
 
-	body, err := res.Raw()
+	resp, err := client.Get(KubernetesDefaultIssuer + "/.well-known/openid-configuration")
 	if err != nil {
 		return nil, fmt.Errorf("could not get response: %w", err)
 	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("could not read response body: %w", err)
+	}
 
 	openIdConfig := &openIDMetadata{}
 	if err := json.Unmarshal(body, openIdConfig); err != nil {